DISA STIG for Red Hat Enterprise Linux 6
This profile contains configuration checks that align to the DISA STIG for Red Hat Enterprise Linux 6. In addition to being applicable to RHEL6, DISA recognizes this configuration baseline as applicable to the operating system tier of Red Hat technologies that are based off RHEL6, such as RHEL Server, RHV-H, RHEL for HPC, RHEL Workstation, and Red Hat Storage deployments.

ID | Severity | Title | Discussion (Rationale) | Fix Text (Description) | Check Text (OCIL Check) | SRG Refs | CCI Refs | 800-53 Refs

partition_for_tmp

unknown

Ensure /tmp Located On Separate Partition

The `/tmp` partition is used as temporary storage by many programs. Placing `/tmp` in its own partition enables the setting of more restrictive mount options, which can help protect programs which use it.

The `/tmp` directory is a world-writable directory used for temporary file storage. Ensure it has its own partition or logical volume at installation time, or migrate it using LVM.

CCI-NaN

partition_for_var

unknown

Ensure /var Located On Separate Partition

Ensuring that `/var` is mounted on its own partition enables the setting of more restrictive mount options. This helps protect system services such as daemons or other programs which use it. It is not uncommon for the `/var` directory to contain world-writable directories installed by other software packages.

The `/var` directory is used by daemons and other system services to store frequently-changing data. Ensure that `/var` has its own partition or logical volume at installation time, or migrate it using LVM.

CCI-NaN

partition_for_var_log | unknown | Ensure /var/log Located On Separate Partition | Placing `/var/log` in its own partition enables better separation between log files and other files in `/var/`. | System logs are stored in the `/var/log` directory. Ensure that it has its own partition or logical volume at installation time, or migrate it using LVM. |  |  | CCI-NaN |

partition_for_var_log_audit

unknown

Ensure /var/log/audit Located On Separate Partition

Placing `/var/log/audit` in its own partition enables better separation between audit files and other files, and helps ensure that auditing cannot be halted due to the partition running out of space.

Audit logs are stored in the `/var/log/audit` directory. Ensure that it has its own partition or logical volume at installation time, or migrate it later using LVM. Make absolutely certain that it is large enough to store all audit logs that will be created by the auditing daemon.

CCI-NaN
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CCI-NaN

partition_for_home

unknown

Ensure /home Located On Separate Partition

Ensuring that `/home` is mounted on its own partition enables the setting of more restrictive mount options, and also helps ensure that users cannot trivially fill partitions used for log or audit data storage.

If user home directories will be stored locally, create a separate partition for `/home` at installation time (or migrate it later using LVM). If `/home` will be mounted from another system such as an NFS server, then creating a separate partition is not necessary at installation time, and the mountpoint can instead be configured later.

CCI-NaN

ensure_redhat_gpgkey_installed

high

Ensure Red Hat GPG Key Installed

The Red Hat GPG key is necessary to cryptographically verify packages are from Red Hat.

To ensure the system can cryptographically verify base software packages come from Red Hat (and to connect to the Red Hat Network to receive them), the Red Hat GPG key must properly be installed. To install the Red Hat GPG key, run:

    $ sudo subscription-manager register

If the system is not connected to the Internet or an RHN Satellite, then install the Red Hat GPG key from trusted media such as the Red Hat installation CD-ROM or DVD. Assuming the disc is mounted in `/media/cdrom`, use the following command as the root user to import it into the keyring:

    $ sudo rpm --import /media/cdrom/RPM-GPG-KEY

CCI-NaN

service_rhnsd_disabled

unknown

Disable Red Hat Network Service (rhnsd)

Although systems management and patching is extremely important to system security, management by a system outside the enterprise enclave is not desirable for some environments. However, if the system is being managed by RHN or RHN Satellite Server the `rhnsd` daemon can remain on.

The Red Hat Network service automatically queries Red Hat Network servers to determine whether there are any actions that should be executed, such as package updates. This only occurs if the system was registered to an RHN server or satellite and managed as such. The `rhnsd` service can be disabled with the following command:

    $ sudo chkconfig rhnsd off

CCI-NaN

security_patches_up_to_date

medium

Ensure Software Patches Installed

Installing software updates is a fundamental mitigation against the exploitation of publicly-known vulnerabilities.

If the system is joined to the Red Hat Network, a Red Hat Satellite Server, or a yum server, run the following command to install updates:

    $ sudo yum update

If the system is not configured to use one of these sources, updates (in the form of RPM packages) can be manually downloaded from the Red Hat Network and installed using `rpm`.

CCI-NaN
CCI-NaN

ensure_gpgcheck_globally_activated

medium

Ensure gpgcheck Enabled In Main Yum Configuration

Ensuring the validity of packages' cryptographic signatures prior to installation ensures the authenticity of the software and protects against malicious tampering.

The `gpgcheck` option controls whether RPM packages' signatures are always checked prior to installation. To configure yum to check package signatures before installing them, ensure the following line appears in `/etc/yum.conf` in the `[main]` section:

    gpgcheck=1

CCI-NaN
CCI-NaN

ensure_gpgcheck_never_disabled

low

Ensure gpgcheck Enabled For All Yum Package Repositories

Ensuring all packages' cryptographic signatures are valid prior to installation ensures the authenticity of the software and protects against malicious tampering.

To ensure signature checking is not disabled for any repos, remove any lines from files in `/etc/yum.repos.d` of the form:

    gpgcheck=0

CCI-NaN
CCI-NaN

package_aide_installed

medium

Install AIDE

The AIDE package must be installed if it is to be available for integrity checking.

Install the AIDE package with the command:

    $ sudo yum install aide

CCI-NaN

enable_selinux_bootloader

medium

Ensure SELinux Not Disabled in /etc/grub.conf

Disabling a major host protection feature, such as SELinux, at boot time prevents it from confining system services at boot time. Further, it increases the chances that it will remain off during system operation.

SELinux can be disabled at boot time by an argument in `/etc/grub.conf`. Remove any instances of `selinux=0` from the kernel arguments in that file to prevent SELinux from being disabled at boot.

CCI-NaN
CCI-NaN

no_rsh_trust_files

high

Remove Rsh Trust Files

Trust files are convenient, but when used in conjunction with the R-services, they can allow unauthenticated access to a system.

The files `/etc/hosts.equiv` and `~/.rhosts` (in each user's home directory) list remote hosts and users that are trusted by the local system when using the rshd daemon. To remove these files, run the following command to delete them from any location:

    $ sudo rm /etc/hosts.equiv

    $ rm ~/.rhosts

CCI-NaN

selinux_state

medium

Ensure SELinux State is Enforcing

Setting the SELinux state to enforcing ensures SELinux is able to confine potentially compromised processes to the security policy, which is designed to prevent them from causing damage to the system or further elevating their privileges.

The SELinux state should be set to `` at system boot time. In the file `/etc/selinux/config`, add or correct the following line to configure the system to boot into enforcing mode:

    SELINUX=

CCI-NaN
CCI-NaN
CCI-NaN

selinux_policytype

unknown

Configure SELinux Policy

Setting the SELinux policy to `targeted` or a more specialized policy ensures the system will confine processes that are likely to be targeted for exploitation, such as network or system services. Note: During the development or debugging of SELinux modules, it is common to temporarily place non-production systems in `permissive` mode. In such temporary cases, SELinux policies should be developed, and once work is completed, the system should be reconfigured to ``.

The SELinux `targeted` policy is appropriate for general-purpose desktops and servers, as well as systems in many other roles. To configure the system to use this policy, add or correct the following line in `/etc/selinux/config`:

    SELINUXTYPE=

Other policies, such as `mls`, provide additional security labeling and greater confinement but are not compatible with many general-purpose use cases.

CCI-NaN
CCI-NaN

selinux_all_devicefiles_labeled

unknown

Ensure No Device Files are Unknown to SELinux

If a device file carries the SELinux type `device_t`, then SELinux cannot properly restrict access to the device file.

Device files, which are used for communication with important system resources, should be labeled with proper SELinux types. If any device files carry the SELinux type `device_t`, report the bug so that policy can be corrected. Supply information about what the device is and what programs use it.

CCI-NaN
CCI-NaN

securetty_root_login_console_only

medium

Restrict Virtual Console Root Logins

Preventing direct root login to virtual console devices helps ensure accountability for actions taken on the system using the root account.

To restrict root logins through the (deprecated) virtual console devices, ensure lines of this form do not appear in `/etc/securetty`:

    vc/1
    vc/2
    vc/3
    vc/4

CCI-NaN

restrict_serial_port_logins

unknown

Restrict Serial Port Root Logins

Preventing direct root login to serial port interfaces helps ensure accountability for actions taken on the systems using the root account.

To restrict root logins on serial ports, ensure lines of this form do not appear in `/etc/securetty`:

    ttyS0
    ttyS1

CCI-NaN

no_shelllogin_for_systemaccounts

medium

Ensure that System Accounts Do Not Run a Shell Upon Login

Ensuring shells are not given to system accounts upon login makes it more difficult for attackers to make use of system accounts.

Some accounts are not associated with a human user of the system, and exist to perform some administrative function. Should an attacker be able to log into these accounts, they should not be granted access to a shell.
The login shell for each local account is stored in the last field of each line in `/etc/passwd`. System accounts are those user accounts with a user ID less than UID_MIN, where value of the UID_MIN directive is set in /etc/login.defs configuration file. In the default configuration UID_MIN is set to 500, thus system accounts are those user accounts with a user ID less than 500. The user ID is stored in the third field. If any system account SYSACCT (other than root) has a login shell, disable it with the command:

    $ sudo usermod -s /sbin/nologin SYSACCT

CCI-NaN

no_empty_passwords

high

Prevent Log In to Accounts With Empty Password

If an account has an empty password, anyone could log in and run commands with the privileges of that account. Accounts with empty passwords should never be used in operational environments.

If an account is configured for password authentication but does not have an assigned password, it may be possible to log onto the account without authentication. Remove any instances of the `nullok` option in `/etc/pam.d/system-auth` to prevent logins with empty passwords.

file_permissions_unauthorized_sgid

unknown

Ensure All SGID Executables Are Authorized

Executable files with the SGID permission run with the privileges of the owner of the file. SGID files of uncertain provenance could allow for unprivileged users to elevate privileges. The presence of these files should be strictly controlled on the system.

The SGID (set group id) bit should be set only on files that were installed via authorized means. A straightforward means of identifying unauthorized SGID files is determine if any were not installed as part of an RPM package, which is cryptographically verified. Investigate the origin of any unpackaged SGID files.

file_permissions_unauthorized_suid

unknown

Ensure All SUID Executables Are Authorized

Executable files with the SUID permission run with the privileges of the owner of the file. SUID files of uncertain provenance could allow for unprivileged users to elevate privileges. The presence of these files should be strictly controlled on the system.

The SUID (set user id) bit should be set only on files that were installed via authorized means. A straightforward means of identifying unauthorized SGID files is determine if any were not installed as part of an RPM package, which is cryptographically verified. Investigate the origin of any unpackaged SUID files.

accounts_root_path_dirs_no_write

unknown

Ensure that Root's Path Does Not Include World or Group-Writable Directories

Such entries increase the risk that root could execute code provided by unprivileged users, and potentially malicious code.

For each element in root's path, run:

    $ sudo ls -ld DIR

and ensure that write permissions are disabled for group and other.

CCI-NaN

accounts_password_all_shadowed

medium

Verify All Account Password Hashes are Shadowed

The hashes for all user account passwords should be stored in the file `/etc/shadow` and never in `/etc/passwd`, which is readable by all users.

If any password hashes are stored in `/etc/passwd` (in the second field, instead of an `x`), the cause of this misconfiguration should be investigated. The account should have its password reset and the hash should be properly stored, or the account should be deleted entirely.

CCI-NaN

accounts_no_uid_except_zero

medium

Verify Only Root Has UID 0

An account has root authority if it has a UID of 0. Multiple accounts with a UID of 0 afford more opportunity for potential intruders to guess a password for a privileged account. Proper configuration of sudo is recommended to afford multiple system administrators access to root privileges in an accountable manner.

If any account other than root has a UID of 0, this misconfiguration should be investigated and the accounts other than root should be removed or have their UID changed.

CCI-NaN

userowner_shadow_file

medium

Verify User Who Owns shadow File

The `/etc/shadow` file contains the list of local system accounts and stores password hashes. Protection of this file is critical for system security. Failure to give ownership of this file to root provides the designated owner with access to sensitive information which could weaken the system security posture.

To properly set the owner of `/etc/shadow`, run the command:

    $ sudo chown root /etc/shadow

CCI-NaN

groupowner_shadow_file

medium

Verify Group Who Owns shadow File

The `/etc/shadow` file stores password hashes. Protection of this file is critical for system security.

To properly set the group owner of `/etc/shadow`, run the command:

    $ sudo chgrp root /etc/shadow

CCI-NaN

file_permissions_etc_shadow

medium

Verify Permissions on shadow File

The `/etc/shadow` file contains the list of local system accounts and stores password hashes. Protection of this file is critical for system security. Failure to give ownership of this file to root provides the designated owner with access to sensitive information which could weaken the system security posture.

To properly set the permissions of `/etc/shadow`, run the command:

    $ sudo chmod 0000 /etc/shadow

CCI-NaN

file_owner_etc_gshadow

medium

Verify User Who Owns gshadow File

The `/etc/gshadow` file contains group password hashes. Protection of this file is critical for system security.

To properly set the owner of `/etc/gshadow`, run the command:

    $ sudo chown root /etc/gshadow

CCI-NaN

file_groupowner_etc_gshadow

medium

Verify Group Who Owns gshadow File

The `/etc/gshadow` file contains group password hashes. Protection of this file is critical for system security.

To properly set the group owner of `/etc/gshadow`, run the command:

    $ sudo chgrp root /etc/gshadow

CCI-NaN

file_permissions_etc_gshadow

medium

Verify Permissions on gshadow File

The `/etc/gshadow` file contains group password hashes. Protection of this file is critical for system security.

To properly set the permissions of `/etc/gshadow`, run the command:

    $ sudo chmod 0000 /etc/gshadow

CCI-NaN

file_owner_etc_passwd

medium

Verify User Who Owns passwd File

The `/etc/passwd` file contains information about the users that are configured on the system. Protection of this file is critical for system security.

To properly set the owner of `/etc/passwd`, run the command:

    $ sudo chown root /etc/passwd

CCI-NaN

file_groupowner_etc_passwd

medium

Verify Group Who Owns passwd File

The `/etc/passwd` file contains information about the users that are configured on the system. Protection of this file is critical for system security.

To properly set the group owner of `/etc/passwd`, run the command:

    $ sudo chgrp root /etc/passwd

CCI-NaN

file_permissions_etc_passwd

medium

Verify Permissions on passwd File

If the `/etc/passwd` file is writable by a group-owner or the world the risk of its compromise is increased. The file contains the list of accounts on the system and associated information, and protection of this file is critical for system security.

To properly set the permissions of `/etc/passwd`, run the command:

    $ sudo chmod 0644 /etc/passwd

CCI-NaN

file_owner_etc_group

medium

Verify User Who Owns group File

The `/etc/group` file contains information regarding groups that are configured on the system. Protection of this file is important for system security.

To properly set the owner of `/etc/group`, run the command:

    $ sudo chown root /etc/group

file_groupowner_etc_group

medium

Verify Group Who Owns group File

The `/etc/group` file contains information regarding groups that are configured on the system. Protection of this file is important for system security.

To properly set the group owner of `/etc/group`, run the command:

    $ sudo chgrp root /etc/group

CCI-NaN

file_permissions_etc_group

medium

Verify Permissions on group File

The `/etc/group` file contains information regarding groups that are configured on the system. Protection of this file is important for system security.

To properly set the permissions of `/etc/group`, run the command:

    $ sudo chmod 644 /etc/group

CCI-NaN

file_permissions_library_dirs

medium

Verify that Shared Library Files Have Restrictive Permissions

Files from shared library directories are loaded into the address space of processes (including privileged ones) or of the kernel itself at runtime. Restrictive permissions are necessary to protect the integrity of the system.

System-wide shared library files, which are linked to executables during process load time or run time, are stored in the following directories by default:

    /lib
    /lib64
    /usr/lib
    /usr/lib64

Kernel modules, which can be added to the kernel during runtime, are stored in `/lib/modules`. All files in these directories should not be group-writable or world-writable. If any file in these directories is found to be group-writable or world-writable, correct its permission with the following command:

    $ sudo chmod go-w FILE

CCI-NaN

file_ownership_library_dirs

medium

Verify that Shared Library Files Have Root Ownership

Files from shared library directories are loaded into the address space of processes (including privileged ones) or of the kernel itself at runtime. Proper ownership is necessary to protect the integrity of the system.

System-wide shared library files, which are linked to executables during process load time or run time, are stored in the following directories by default:

    /lib
    /lib64
    /usr/lib
    /usr/lib64

Kernel modules, which can be added to the kernel during runtime, are also stored in `/lib/modules`. All files in these directories should be owned by the `root` user. If the directory, or any file in these directories, is found to be owned by a user other than root correct its ownership with the following command:

    $ sudo chown root FILE

CCI-NaN

file_permissions_binary_dirs

medium

Verify that System Executables Have Restrictive Permissions

System binaries are executed by privileged users, as well as system services, and restrictive permissions are necessary to ensure execution of these programs cannot be co-opted.

System executables are stored in the following directories by default:

    /bin
    /sbin
    /usr/bin
    /usr/libexec
    /usr/local/bin
    /usr/local/sbin
    /usr/sbin

All files in these directories should not be group-writable or world-writable. If any file FILE in these directories is found to be group-writable or world-writable, correct its permission with the following command:

    $ sudo chmod go-w FILE

CCI-NaN

file_ownership_binary_dirs

medium

Verify that System Executables Have Root Ownership

System binaries are executed by privileged users as well as system services, and restrictive permissions are necessary to ensure that their execution of these programs cannot be co-opted.

System executables are stored in the following directories by default:

    /bin
    /sbin
    /usr/bin
    /usr/libexec
    /usr/local/bin
    /usr/local/sbin
    /usr/sbin

All files in these directories should be owned by the `root` user. If any file FILE in these directories is found to be owned by a user other than root, correct its ownership with the following command:

    $ sudo chown root FILE

CCI-NaN

file_permissions_var_log_audit

unknown

System Audit Logs Must Have Mode 0640 or Less Permissive

If users can write to audit logs, audit trails can be modified or destroyed.

If `log_group` in `/etc/audit/auditd.conf` is set to a group other than the `root` group account, change the mode of the audit log files with the following command:

    $ sudo chmod 0640 audit_file

Otherwise, change the mode of the audit log files with the following command:

    $ sudo chmod 0600 audit_file

CCI-NaN

accounts_password_minlen_login_defs

medium

Set Password Minimum Length in login.defs

Requiring a minimum password length makes password cracking attacks more difficult by ensuring a larger search space. However, any security benefit from an onerous requirement must be carefully weighed against usability problems, support costs, or counterproductive behavior that may result.

To specify password length requirements for new accounts, edit the file `/etc/login.defs` and add or correct the following lines:

    PASS_MIN_LEN

As of the DISA Red Hat 6 STIG - Ver 1, Rel 13 (28-OCT-2016), the DoD requirement is now `15`. The FISMA requirement is `12`. If a program consults `/etc/login.defs` and also another PAM module (such as `pam_cracklib`) during a password change operation, then the most restrictive must be satisfied. See PAM section for more information about enforcing password quality requirements.

CCI-NaN

accounts_minimum_age_login_defs

medium

Set Password Minimum Age

Setting the minimum password age protects against users cycling back to a favorite password after satisfying the password reuse requirement.

To specify password minimum age for new accounts, edit the file `/etc/login.defs` and add or correct the following line:

    PASS_MIN_DAYS

A value of 1 day is considered sufficient for many environments. The DoD requirement is 1.

CCI-NaN

accounts_maximum_age_login_defs

medium

Set Password Maximum Age

Setting the password maximum age ensures users are required to periodically change their passwords. This could possibly decrease the utility of a stolen password. Requiring shorter password lifetimes increases the risk of users writing down the password in a convenient location subject to physical compromise.

To specify password maximum age for new accounts, edit the file `/etc/login.defs` and add or correct the following line:

    PASS_MAX_DAYS

A value of 180 days is sufficient for many environments. The DoD requirement is 60.

CCI-NaN
CCI-NaN

accounts_password_warn_age_login_defs

unknown

Set Password Warning Age

Setting the password warning age enables users to make the change at a practical time.

To specify how many days prior to password expiration that a warning will be issued to users, edit the file `/etc/login.defs` and add or correct the following line:

    PASS_WARN_AGE

The DoD requirement is 7.

accounts_password_pam_retry

unknown

Set Password Retry Prompts Permitted Per-Session

Setting the password retry prompts that are permitted on a per-session basis to a low value requires some software, such as SSH, to re-connect. This can slow down and draw additional attention to some types of password-guessing attacks. Note that this is different from account lockout, which is provided by the pam_faillock module.

To configure the number of retry prompts that are permitted per-session:
Edit the `pam_cracklib.so` statement in `/etc/pam.d/system-auth` to show `retry=`, or a lower value if site policy is more restrictive.
The DoD requirement is a maximum of 3 prompts per session.

CCI-NaN

accounts_password_pam_dcredit

unknown

Set Password Strength Minimum Digit Characters

Requiring digits makes password guessing attacks more difficult by ensuring a larger search space.

The pam_cracklib module's `dcredit` parameter controls requirements for usage of digits in a password. When set to a negative number, any password will be required to contain that many digits. When set to a positive number, pam_cracklib will grant +1 additional length credit for each digit. Add `dcredit=-1` after pam_cracklib.so to require use of a digit in passwords.

CCI-NaN

accounts_password_pam_ucredit

unknown

Set Password Strength Minimum Uppercase Characters

Requiring a minimum number of uppercase characters makes password guessing attacks more difficult by ensuring a larger search space.

The pam_cracklib module's `ucredit=` parameter controls requirements for usage of uppercase letters in a password. When set to a negative number, any password will be required to contain that many uppercase characters. When set to a positive number, pam_cracklib will grant +1 additional length credit for each uppercase character. Add `ucredit=-1` after pam_cracklib.so to require use of an upper case character in passwords.

CCI-NaN

accounts_password_pam_ocredit

unknown

Set Password Strength Minimum Special Characters

Requiring a minimum number of special characters makes password guessing attacks more difficult by ensuring a larger search space.

The pam_cracklib module's `ocredit=` parameter controls requirements for usage of special (or ``other'') characters in a password. When set to a negative number, any password will be required to contain that many special characters. When set to a positive number, pam_cracklib will grant +1 additional length credit for each special character. Add `ocredit=` after pam_cracklib.so to require use of a special character in passwords.

CCI-NaN

accounts_password_pam_lcredit

unknown

Set Password Strength Minimum Lowercase Characters

Requiring a minimum number of lowercase characters makes password guessing attacks more difficult by ensuring a larger search space.

The pam_cracklib module's `lcredit=` parameter controls requirements for usage of lowercase letters in a password. When set to a negative number, any password will be required to contain that many lowercase characters. When set to a positive number, pam_cracklib will grant +1 additional length credit for each lowercase character. Add `lcredit=-1` after pam_cracklib.so to require use of a lowercase character in passwords.

CCI-NaN

accounts_password_pam_difok

unknown

Set Password Strength Minimum Different Characters

Requiring a minimum number of different characters during password changes ensures that newly changed passwords should not resemble previously compromised ones. Note that passwords which are changed on compromised systems will still be compromised, however.

The pam_cracklib module's `difok` parameter controls requirements for usage of different characters during a password change. Add `difok=` after pam_cracklib.so to require differing characters when changing passwords. The DoD requirement is `4`.

CCI-NaN

accounts_passwords_pam_faillock_deny

medium

Set Deny For Failed Password Attempts

Locking out user accounts after a number of incorrect attempts prevents direct password guessing attacks.

To configure the system to lock out accounts after a number of incorrect login attempts using `pam_faillock.so`, modify the content of both `/etc/pam.d/system-auth` and `/etc/pam.d/password-auth` as follows:

- Add the following line immediately `before` the `pam_unix.so` statement in the `AUTH` section:

      auth required pam_faillock.so preauth silent deny= unlock_time= fail_interval=

- Add the following line immediately `after` the `pam_unix.so` statement in the `AUTH` section:

      auth [default=die] pam_faillock.so authfail deny= unlock_time= fail_interval=

- Add the following line immediately `before` the `pam_unix.so` statement in the `ACCOUNT` section:

      account required pam_faillock.so

CCI-NaN

set_password_hashing_algorithm_systemauth

medium

Set Password Hashing Algorithm in /etc/pam.d/system-auth

Using a stronger hashing algorithm makes password cracking attacks more difficult.

In `/etc/pam.d/system-auth`, the `password` section of the file controls which PAM modules execute during a password change. Set the `pam_unix.so` module in the `password` section to include the argument `sha512`, as shown below:

    password    sufficient    pam_unix.so sha512 other arguments...

This will help ensure when local users change their passwords, hashes for the new passwords will be generated using the SHA-512 algorithm. This is the default.

CCI-NaN

set_password_hashing_algorithm_logindefs

medium

Set Password Hashing Algorithm in /etc/login.defs

Using a stronger hashing algorithm makes password cracking attacks more difficult.

In `/etc/login.defs`, add or correct the following line to ensure the system will use SHA-512 as the hashing algorithm:

    ENCRYPT_METHOD SHA512

CCI-NaN

set_password_hashing_algorithm_libuserconf

medium

Set Password Hashing Algorithm in /etc/libuser.conf

Using a stronger hashing algorithm makes password cracking attacks more difficult.

In `/etc/libuser.conf`, add or correct the following line in its `[defaults]` section to ensure the system will use the SHA-512 algorithm for password hashing:

    crypt_style = sha512

CCI-NaN

file_user_owner_grub_conf

medium

Verify /etc/grub.conf User Ownership

Only root should be able to modify important boot parameters.

The file `/etc/grub.conf` should be owned by the `root` user to prevent destruction or modification of the file. To properly set the owner of `/etc/grub.conf`, run the command:

    $ sudo chown root /etc/grub.conf

CCI-NaN

file_group_owner_grub_conf

medium

Verify /etc/grub.conf Group Ownership

The `root` group is a highly-privileged group. Furthermore, the group-owner of this file should not have any access privileges anyway.

The file `/etc/grub.conf` should be group-owned by the `root` group to prevent destruction or modification of the file. To properly set the group owner of `/etc/grub.conf`, run the command:

    $ sudo chgrp root /etc/grub.conf

CCI-NaN

file_permissions_grub_conf

medium

Verify /boot/grub/grub.conf Permissions

Proper permissions ensure that only the root user can modify important boot parameters.

File permissions for `/boot/grub/grub.conf` should be set to 600, which is the default. To properly set the permissions of `/boot/grub/grub.conf`, run the command:

    $ sudo chmod 600 /boot/grub/grub.conf

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bootloader_password

medium

Set Boot Loader Password

Password protection on the boot loader configuration ensures users with physical access cannot trivially alter important bootloader settings. These include which kernel to use, and whether to enter single-user mode.

The grub boot loader should have password protection enabled to protect boot-time settings. To do so, select a password and then generate a hash from it by running the following command:

    $ grub-crypt --sha-512

When prompted to enter a password, insert the following line into `/etc/grub.conf` immediately after the header comments. (Use the output from `grub-crypt` as the value of password-hash):

    password --encrypted password-hash

NOTE: To meet FISMA Moderate, the bootloader password MUST differ from the root password.

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require_singleuser_auth

medium

Require Authentication for Single User Mode

This prevents attackers with physical access from trivially bypassing security on the machine and gaining root access. Such accesses are further prevented by configuring the bootloader password.

Single-user mode is intended as a system recovery method, providing a single user root access to the system by providing a boot option at startup. By default, no authentication is performed if single-user mode is selected.
To require entry of the root password even if the system is started in single-user mode, add or correct the following line in the file `/etc/sysconfig/init`:

    SINGLE=/sbin/sulogin

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disable_interactive_boot

medium

Disable Interactive Boot

Using interactive boot, the console user could disable auditing, firewalls, or other services, weakening system security.

To disable the ability for users to perform interactive startups, perform both of the following:

1. Edit the file `/etc/sysconfig/init`. Add or correct the line:

       PROMPT=no

2. Inspect the kernel boot arguments (which follow the word `kernel`) in `/etc/grub.conf` and ensure the `confirm` argument is not present.

Both the `PROMPT` option of the `/etc/sysconfig/init` file and the `confirm` kernel boot argument of the `/etc/grub.conf` file allow the console user to perform an interactive system startup, in which it is possible to select the set of services which are started on boot.

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package_screen_installed

unknown

Install the screen Package

Installing `screen` ensures a console locking capability is available for users who may need to suspend console logins.

To enable console screen locking, install the `screen` package:

    $ sudo yum install screen

Instruct users to begin new terminal sessions with the following command:

    $ screen

The console can now be locked with the following key combination:

    ctrl+a x

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banner_etc_issue

medium

Modify the System Login Banner

An appropriate warning message reinforces policy awareness during the login process and facilitates possible legal action against attackers.

To configure the system login banner:
Edit `/etc/issue`. Replace the default text with a message compliant with the local site policy or a legal disclaimer. The DoD required text is either:
`You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only. By using this IS (which includes any device attached to this IS), you consent to the following conditions:
-The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations.
-At any time, the USG may inspect and seize data stored on this IS.
-Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose.
-This IS includes security measures (e.g., authentication and access controls) to protect USG interests -- not for your personal benefit or privacy.
-Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details.`
OR:
`Use of this or any other DoD interest computer system constitutes consent to monitoring at all times.
This is a DoD interest computer system. All DoD interest computer systems and related equipment are intended for the communication, transmission, processing, and storage of official U.S. Government or other authorized information only. All DoD interest computer systems are subject to monitoring at all times to ensure proper functioning of equipment and systems including security devices and systems, to prevent unauthorized use and violations of statutes and security regulations, to deter criminal activity, and for other similar purposes. Any user of a DoD interest computer system should be aware that any information placed in the system is subject to monitoring and is not subject to any expectation of privacy.
If monitoring of this or any other DoD interest computer system reveals possible evidence of violation of criminal statutes, this evidence and any other related information, including identification information about the user, may be provided to law enforcement officials. If monitoring of this or any other DoD interest computer systems reveals violations of security regulations or unauthorized use, employees who violate security regulations or make unauthorized use of DoD interest computer systems are subject to appropriate disciplinary action.
Use of this or any other DoD interest computer system constitutes consent to monitoring at all times.`
OR:
`I've read & consent to terms in IS user agreem't.`

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sysctl_kernel_randomize_va_space

medium

Enable Randomized Layout of Virtual Address Space

Address space layout randomization (ASLR) makes it more difficult for an attacker to predict the location of attack code they have introduced into a process's address space during an attempt at exploitation. Additionally, ASLR makes it more difficult for an attacker to know the location of existing code in order to re-purpose it using return oriented programming (ROP) techniques.

To set the runtime status of the `kernel.randomize_va_space` kernel parameter, run the following command:

    $ sudo sysctl -w kernel.randomize_va_space=2

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    kernel.randomize_va_space = 2

sysctl_kernel_exec_shield

medium

Enable ExecShield

ExecShield uses the segmentation feature on all x86 systems to prevent execution in memory higher than a certain address. It writes an address as a limit in the code segment descriptor, to control where code can be executed, on a per-process basis. When the kernel places a process's memory regions such as the stack and heap higher than this address, the hardware prevents execution in that address range.

To set the runtime status of the `kernel.exec-shield` kernel parameter, run the following command:

    $ sudo sysctl -w kernel.exec-shield=1

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    kernel.exec-shield = 1

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sysctl_net_ipv4_conf_default_send_redirects

medium

Disable Kernel Parameter for Sending ICMP Redirects by Default

Sending ICMP redirects permits the system to instruct other systems to update their routing information. The ability to send ICMP redirects is only appropriate for systems acting as routers.

To set the runtime status of the `net.ipv4.conf.default.send_redirects` kernel parameter, run the following command:

    $ sudo sysctl -w net.ipv4.conf.default.send_redirects=0

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    net.ipv4.conf.default.send_redirects = 0

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sysctl_net_ipv4_conf_all_send_redirects

medium

Disable Kernel Parameter for Sending ICMP Redirects for All Interfaces

Sending ICMP redirects permits the system to instruct other systems to update their routing information. The ability to send ICMP redirects is only appropriate for systems acting as routers.

To set the runtime status of the `net.ipv4.conf.all.send_redirects` kernel parameter, run the following command:

    $ sudo sysctl -w net.ipv4.conf.all.send_redirects=0

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    net.ipv4.conf.all.send_redirects = 0

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sysctl_net_ipv4_ip_forward

medium

Disable Kernel Parameter for IP Forwarding

IP forwarding permits the kernel to forward packets from one network interface to another. The ability to forward packets between two networks is only appropriate for systems acting as routers.

To set the runtime status of the `net.ipv4.ip_forward` kernel parameter, run the following command:

    $ sudo sysctl -w net.ipv4.ip_forward=0

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    net.ipv4.ip_forward = 0

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sysctl_net_ipv4_conf_all_accept_source_route

medium

Configure Kernel Parameter for Accepting Source-Routed Packets for All Interfaces

Accepting source-routed packets in the IPv4 protocol has few legitimate uses. It should be disabled unless it is absolutely required.

To set the runtime status of the `net.ipv4.conf.all.accept_source_route` kernel parameter, run the following command:

    $ sudo sysctl -w net.ipv4.conf.all.accept_source_route=0

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    net.ipv4.conf.all.accept_source_route = 0

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sysctl_net_ipv4_conf_all_accept_redirects

medium

Configure Kernel Parameter for Accepting ICMP Redirects for All Interfaces

Accepting ICMP redirects has few legitimate uses. It should be disabled unless it is absolutely required.

To set the runtime status of the `net.ipv4.conf.all.accept_redirects` kernel parameter, run the following command:

    $ sudo sysctl -w net.ipv4.conf.all.accept_redirects=0

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    net.ipv4.conf.all.accept_redirects = 0

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sysctl_net_ipv4_conf_all_secure_redirects

medium

Configure Kernel Parameter for Accepting Secure Redirects for All Interfaces

Accepting "secure" ICMP redirects (from those gateways listed as default gateways) has few legitimate uses. It should be disabled unless it is absolutely required.

To set the runtime status of the `net.ipv4.conf.all.secure_redirects` kernel parameter, run the following command:

    $ sudo sysctl -w net.ipv4.conf.all.secure_redirects=0

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    net.ipv4.conf.all.secure_redirects = 0

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sysctl_net_ipv4_conf_all_log_martians

unknown

Configure Kernel Parameter to Log Martian Packets

The presence of "martian" packets (which have impossible addresses) as well as spoofed packets, source-routed packets, and redirects could be a sign of nefarious network activity. Logging these packets enables this activity to be detected.

To set the runtime status of the `net.ipv4.conf.all.log_martians` kernel parameter, run the following command:

    $ sudo sysctl -w net.ipv4.conf.all.log_martians=1

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    net.ipv4.conf.all.log_martians = 1

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sysctl_net_ipv4_conf_default_accept_source_route

medium

Configure Kernel Parameter for Accepting Source-Routed Packets By Default

Accepting source-routed packets in the IPv4 protocol has few legitimate uses. It should be disabled unless it is absolutely required.

To set the runtime status of the `net.ipv4.conf.default.accept_source_route` kernel parameter, run the following command:

    $ sudo sysctl -w net.ipv4.conf.default.accept_source_route=0

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    net.ipv4.conf.default.accept_source_route = 0

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sysctl_net_ipv4_conf_default_secure_redirects

medium

Configure Kernel Parameter for Accepting Secure Redirects By Default

Accepting "secure" ICMP redirects (from those gateways listed as default gateways) has few legitimate uses. It should be disabled unless it is absolutely required.

To set the runtime status of the `net.ipv4.conf.default.secure_redirects` kernel parameter, run the following command:

    $ sudo sysctl -w net.ipv4.conf.default.secure_redirects=0

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    net.ipv4.conf.default.secure_redirects = 0

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sysctl_net_ipv4_conf_default_accept_redirects

unknown

Configure Kernel Parameter for Accepting ICMP Redirects By Default

This feature of the IPv4 protocol has few legitimate uses. It should be disabled unless it is absolutely required.

To set the runtime status of the `net.ipv4.conf.default.accept_redirects` kernel parameter, run the following command:

    $ sudo sysctl -w net.ipv4.conf.default.accept_redirects=0

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    net.ipv4.conf.default.accept_redirects = 0

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sysctl_net_ipv4_icmp_echo_ignore_broadcasts

unknown

Configure Kernel Parameter to Ignore ICMP Broadcast Echo Requests

Ignoring ICMP echo requests (pings) sent to broadcast or multicast addresses makes the system slightly more difficult to enumerate on the network.

To set the runtime status of the `net.ipv4.icmp_echo_ignore_broadcasts` kernel parameter, run the following command:

    $ sudo sysctl -w net.ipv4.icmp_echo_ignore_broadcasts=1

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    net.ipv4.icmp_echo_ignore_broadcasts = 1

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sysctl_net_ipv4_icmp_ignore_bogus_error_responses

unknown

Configure Kernel Parameter to Ignore Bogus ICMP Error Responses

Ignoring bogus ICMP error responses reduces log size, although some activity would not be logged.

To set the runtime status of the `net.ipv4.icmp_ignore_bogus_error_responses` kernel parameter, run the following command:

    $ sudo sysctl -w net.ipv4.icmp_ignore_bogus_error_responses=1

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    net.ipv4.icmp_ignore_bogus_error_responses = 1

sysctl_net_ipv4_tcp_syncookies

medium

Configure Kernel Parameter to Use TCP Syncookies

A TCP SYN flood attack can cause a denial of service by filling a system's TCP connection table with connections in the SYN_RCVD state. Syncookies can be used to track a connection when a subsequent ACK is received, verifying the initiator is attempting a valid connection and is not a flood source. This feature is activated when a flood condition is detected, and enables the system to continue servicing valid connection requests.

To set the runtime status of the `net.ipv4.tcp_syncookies` kernel parameter, run the following command:

    $ sudo sysctl -w net.ipv4.tcp_syncookies=1

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    net.ipv4.tcp_syncookies = 1

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sysctl_net_ipv4_conf_all_rp_filter

medium

Configure Kernel Parameter to Use Reverse Path Filtering for All Interfaces

Enabling reverse path filtering drops packets with source addresses that should not have been able to be received on the interface they were received on. It should not be used on systems which are routers for complicated networks, but is helpful for end hosts and routers serving small networks.

To set the runtime status of the `net.ipv4.conf.all.rp_filter` kernel parameter, run the following command:

    $ sudo sysctl -w net.ipv4.conf.all.rp_filter=1

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    net.ipv4.conf.all.rp_filter = 1

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sysctl_net_ipv4_conf_default_rp_filter

medium

Configure Kernel Parameter to Use Reverse Path Filtering by Default

Enabling reverse path filtering drops packets with source addresses that should not have been able to be received on the interface they were received on. It should not be used on systems which are routers for complicated networks, but is helpful for end hosts and routers serving small networks.

To set the runtime status of the `net.ipv4.conf.default.rp_filter` kernel parameter, run the following command:

    $ sudo sysctl -w net.ipv4.conf.default.rp_filter=1

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    net.ipv4.conf.default.rp_filter = 1

sysctl_net_ipv6_conf_default_accept_redirects

medium

Configure Accepting IPv6 Redirects By Default

An illicit ICMP redirect message could result in a man-in-the-middle attack.

To set the runtime status of the `net.ipv6.conf.default.accept_redirects` kernel parameter, run the following command:

    $ sudo sysctl -w net.ipv6.conf.default.accept_redirects=0

If this is not the system's default value, add the following line to `/etc/sysctl.conf`:

    net.ipv6.conf.default.accept_redirects = 0

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service_ip6tables_enabled

medium

Verify ip6tables Enabled if Using IPv6

The `ip6tables` service provides the system's host-based firewalling capability for IPv6 and ICMPv6.

The `ip6tables` service can be enabled with the following command:

    $ sudo chkconfig --level 2345 ip6tables on

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service_iptables_enabled

medium

Verify iptables Enabled

The `iptables` service provides the system's host-based firewalling capability for IPv4 and ICMP.

The `iptables` service can be enabled with the following command:

    $ sudo chkconfig --level 2345 iptables on

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set_iptables_default_rule

medium

Set Default iptables Policy for Incoming Packets

In `iptables` the default policy is applied only after all the applicable rules in the table are examined for a match. Setting the default policy to `DROP` implements proper design for a firewall, i.e. any packets which are not explicitly permitted should not be accepted.

To set the default policy to DROP (instead of ACCEPT) for the built-in INPUT chain which processes incoming packets, add or correct the following line in `/etc/sysconfig/iptables`:

    :INPUT DROP [0:0]

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set_ip6tables_default_rule

medium

Set Default ip6tables Policy for Incoming Packets

In `ip6tables`, the default policy is applied only after all the applicable rules in the table are examined for a match. Setting the default policy to `DROP` implements proper design for a firewall, i.e. any packets which are not explicitly permitted should not be accepted.

To set the default policy to DROP (instead of ACCEPT) for the built-in INPUT chain which processes incoming packets, add or correct the following line in `/etc/sysconfig/ip6tables`:

    :INPUT DROP [0:0]

If changes were required, reload the ip6tables rules:

    $ sudo service ip6tables reload

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kernel_module_dccp_disabled

medium

Disable DCCP Support

Disabling DCCP protects the system against exploitation of any flaws in its implementation.

The Datagram Congestion Control Protocol (DCCP) is a relatively new transport layer protocol, designed to support streaming media and telephony. To configure the system to prevent the `dccp` kernel module from being loaded, add the following line to a file in the directory `/etc/modprobe.d`:

    install dccp /bin/true

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kernel_module_sctp_disabled

medium

Disable SCTP Support

Disabling SCTP protects the system against exploitation of any flaws in its implementation.

The Stream Control Transmission Protocol (SCTP) is a transport layer protocol, designed to support the idea of message-oriented communication, with several streams of messages within one connection. To configure the system to prevent the `sctp` kernel module from being loaded, add the following line to a file in the directory `/etc/modprobe.d`:

    install sctp /bin/true

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kernel_module_rds_disabled

unknown

Disable RDS Support

Disabling RDS protects the system against exploitation of any flaws in its implementation.

The Reliable Datagram Sockets (RDS) protocol is a transport layer protocol designed to provide reliable high- bandwidth, low-latency communications between nodes in a cluster. To configure the system to prevent the `rds` kernel module from being loaded, add the following line to a file in the directory `/etc/modprobe.d`:

    install rds /bin/true

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kernel_module_tipc_disabled

medium

Disable TIPC Support

Disabling TIPC protects the system against exploitation of any flaws in its implementation.

The Transparent Inter-Process Communication (TIPC) protocol is designed to provide communications between nodes in a cluster. To configure the system to prevent the `tipc` kernel module from being loaded, add the following line to a file in the directory `/etc/modprobe.d`:

    install tipc /bin/true

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package_rsyslog_installed

medium

Ensure rsyslog is Installed

The rsyslog package provides the rsyslog daemon, which provides system logging services.

Rsyslog is installed by default. The `rsyslog` package can be installed with the following command:

    $ sudo yum install rsyslog

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service_rsyslog_enabled

medium

Enable rsyslog Service

The `rsyslog` service must be running in order to provide logging services, which are essential to system administration.

The `rsyslog` service provides syslog-style logging by default on Red Hat Enterprise Linux 6. The `rsyslog` service can be enabled with the following command:

    $ sudo chkconfig --level 2345 rsyslog on

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rsyslog_files_ownership

medium

Ensure Log Files Are Owned By Appropriate User

The log files generated by rsyslog contain valuable information regarding system configuration, user authentication, and other such information. Log files should be protected from unauthorized access.

The owner of all log files written by `rsyslog` should be root. These log files are determined by the second part of each Rule line in `/etc/rsyslog.conf` and typically all appear in `/var/log`. For each log file LOGFILE referenced in `/etc/rsyslog.conf`, run the following command to inspect the file's owner:

    $ ls -l LOGFILE

If the owner is not `root`, run the following command to correct this:

    $ sudo chown root LOGFILE

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rsyslog_files_groupownership

medium

Ensure Log Files Are Owned By Appropriate Group

The log files generated by rsyslog contain valuable information regarding system configuration, user authentication, and other such information. Log files should be protected from unauthorized access.

The group-owner of all log files written by `rsyslog` should be root. These log files are determined by the second part of each Rule line in `/etc/rsyslog.conf` and typically all appear in `/var/log`. For each log file LOGFILE referenced in `/etc/rsyslog.conf`, run the following command to inspect the file's group owner:

    $ ls -l LOGFILE

If the owner is not `root`, run the following command to correct this:

    $ sudo chgrp root LOGFILE

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rsyslog_files_permissions

medium

Ensure System Log Files Have Correct Permissions

Log files can contain valuable information regarding system configuration. If the system log files are not protected unauthorized users could change the logged data, eliminating their forensic value.

The file permissions for all log files written by `rsyslog` should be set to 600, or more restrictive. These log files are determined by the second part of each Rule line in `/etc/rsyslog.conf` and typically all appear in `/var/log`. For each log file LOGFILE referenced in `/etc/rsyslog.conf`, run the following command to inspect the file's permissions:

    $ ls -l LOGFILE

If the permissions are not 600 or more restrictive, run the following command to correct this:

    $ sudo chmod 0600 LOGFILE

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rsyslog_remote_loghost

unknown

Ensure Logs Sent To Remote Host

A log server (loghost) receives syslog messages from one or more systems. This data can be used as an additional log source in the event a system is compromised and its local logs are suspect. Forwarding log messages to a remote loghost also provides system administrators with a centralized place to view the status of multiple hosts within the enterprise.

To configure rsyslog to send logs to a remote log server, open `/etc/rsyslog.conf` and read and understand the last section of the file, which describes the multiple directives necessary to activate remote logging. Along with these other directives, the system can be configured to forward its logs to a particular log server by adding or correcting one of the following lines, substituting `loghost.example.com` appropriately. The choice of protocol depends on the environment of the system; although TCP and RELP provide more reliable message delivery, they may not be supported in all environments.
To use UDP for log message delivery:

    *.* @loghost.example.com

To use TCP for log message delivery:

    *.* @@loghost.example.com

To use RELP for log message delivery:

    *.* :omrelp:loghost.example.com

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ensure_logrotate_activated

unknown

Ensure Logrotate Runs Periodically

Log files that are not properly rotated run the risk of growing so large that they fill up the /var/log partition. Valuable logging information could be lost if the /var/log partition becomes full.

The `logrotate` utility allows for the automatic rotation of log files. The frequency of rotation is specified in `/etc/logrotate.conf`, which triggers a cron task. To configure logrotate to run daily, add or correct the following line in `/etc/logrotate.conf`:

    # rotate log files frequency
    daily

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service_auditd_enabled

medium

Enable auditd Service

Ensuring the `auditd` service is active ensures audit records generated by the kernel can be written to disk, or that appropriate actions will be taken if other obstacles exist.

The `auditd` service is an essential userspace component of the Linux Auditing System, as it is responsible for writing audit records to disk. The `auditd` service can be enabled with the following command:

    $ sudo chkconfig --level 2345 auditd on

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bootloader_audit_argument

low

Enable Auditing for Processes Which Start Prior to the Audit Daemon

Each process on the system carries an "auditable" flag which indicates whether its activities can be audited. Although `auditd` takes care of enabling this for all processes which launch after it does, adding the kernel argument ensures it is set for every process during boot.

To ensure all processes can be audited, even those which start prior to the audit daemon, add the argument `audit=1` to the kernel line in `/etc/grub.conf`, in the manner below:

    kernel /vmlinuz-version ro vga=ext root=/dev/VolGroup00/LogVol00 rhgb quiet audit=1

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auditd_data_retention_num_logs

medium

Configure auditd Number of Logs Retained

The total storage for audit log files must be large enough to retain log information over the period required. This is a function of the maximum log file size and the number of logs retained.

Determine how many log files `auditd` should retain when it rotates logs. Edit the file `/etc/audit/auditd.conf`. Add or modify the following line, substituting NUMLOGS with the correct value of :

    num_logs = NUMLOGS

Set the value to 5 for general-purpose systems. Note that values less than 2 result in no log rotation.

auditd_data_retention_max_log_file

medium

Configure auditd Max Log File Size

The total storage for audit log files must be large enough to retain log information over the period required. This is a function of the maximum log file size and the number of logs retained.

Determine the amount of audit data (in megabytes) which should be retained in each log file. Edit the file `/etc/audit/auditd.conf`. Add or modify the following line, substituting the correct value of for STOREMB:

    max_log_file = STOREMB

Set the value to `6` (MB) or higher for general-purpose systems. Larger values, of course, support retention of even more audit data.

auditd_data_retention_max_log_file_action

medium

Configure auditd max_log_file_action Upon Reaching Maximum Log Size

Automatically rotating logs (by setting this to `rotate`) minimizes the chances of the system unexpectedly running out of disk space by being overwhelmed with log data. However, for systems that must never discard log data, or which use external processes to transfer it and reclaim space, `keep_logs` can be employed.

The default action to take when the logs reach their maximum size is to rotate the log files, discarding the oldest one. To configure the action taken by `auditd`, add or correct the line in `/etc/audit/auditd.conf`:

    max_log_file_action = ACTION

Possible values for ACTION are described in the `auditd.conf` man page. These include:

- `ignore`
- `syslog`
- `suspend`
- `rotate`
- `keep_logs`

Set the `ACTION` to `rotate` to ensure log rotation occurs. This is the default. The setting is case-insensitive.

auditd_data_retention_admin_space_left_action

medium

Configure auditd admin_space_left Action on Low Disk Space

Administrators should be made aware of an inability to record audit records. If a separate partition or logical volume of adequate size is used, running low on space for audit records should never occur.

The `auditd` service can be configured to take an action when disk space is running low but prior to running out of space completely. Edit the file `/etc/audit/auditd.conf`. Add or modify the following line, substituting ACTION appropriately:

    admin_space_left_action = ACTION

Set this value to `single` to cause the system to switch to single-user mode for corrective action. Acceptable values also include `suspend` and `halt`. For certain systems, the need for availability outweighs the need to log all actions, and a different setting should be determined. Details regarding all possible values for ACTION are described in the `auditd.conf` man page.

CCI-NaN
CCI-NaN

audit_rules_time_adjtimex

unknown

Record attempts to alter time through adjtimex

Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited.

On a 32-bit system, add the following to `/etc/audit/audit.rules`:

    # audit_time_rules
    -a always,exit -F arch=b32 -S adjtimex -k audit_time_rules

On a 64-bit system, add the following to `/etc/audit/audit.rules`:

    # audit_time_rules
    -a always,exit -F arch=b64 -S adjtimex -k audit_time_rules

The -k option allows for the specification of a key in string form that can be used for better reporting capability through ausearch and aureport. Multiple system calls can be defined on the same line to save space if desired, but is not required. See an example of multiple combined syscalls:

    -a always,exit -F arch=b64 -S adjtimex -S settimeofday -k audit_time_rules

CCI-NaN
CCI-NaN

audit_rules_time_settimeofday

unknown

Record attempts to alter time through settimeofday

Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited.

On a 32-bit system, add the following to `/etc/audit/audit.rules`:

    # audit_time_rules
    -a always,exit -F arch=b32 -S settimeofday -k audit_time_rules

On a 64-bit system, add the following to `/etc/audit/audit.rules`:

    # audit_time_rules
    -a always,exit -F arch=b64 -S settimeofday -k audit_time_rules

The -k option allows for the specification of a key in string form that can be used for better reporting capability through ausearch and aureport. Multiple system calls can be defined on the same line to save space if desired, but is not required. See an example of multiple combined syscalls:

    -a always,exit -F arch=b64 -S adjtimex -S settimeofday -k audit_time_rules

CCI-NaN
CCI-NaN

audit_rules_time_stime

unknown

Record Attempts to Alter Time Through stime

Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited.

Add the following line to `/etc/audit/audit.rules` for both 32-bit and 64-bit systems:

    # audit_time_rules
    -a always,exit -F arch=b32 -S stime -k audit_time_rules

Since the 64-bit version of the "stime" system call is not defined in the audit lookup table, the corresponding "-F arch=b64" form of this rule is not expected to be defined on 64-bit systems (the aforementioned "-F arch=b32" stime rule form itself is sufficient for both 32-bit and 64-bit systems). The -k option allows for the specification of a key in string form that can be used for better reporting capability through ausearch and aureport. Multiple system calls can be defined on the same line to save space if desired, but is not required. See an example of multiple combined syscalls:

    -a always,exit -F arch=b64 -S adjtimex -S settimeofday -k audit_time_rules

CCI-NaN
CCI-NaN

audit_rules_time_clock_settime

unknown

Record Attempts to Alter Time Through clock_settime

Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited.

On a 32-bit system, add the following to `/etc/audit/audit.rules`:

    # time-change
    -a always,exit -F arch=b32 -S clock_settime -F a0=0x0 -F key=time-change

On a 64-bit system, add the following to `/etc/audit/audit.rules`:

    # time-change
    -a always,exit -F arch=b64 -S clock_settime -F a0=0x0 -F key=time-change

The -k option allows for the specification of a key in string form that can be used for better reporting capability through ausearch and aureport. Multiple system calls can be defined on the same line to save space if desired, but is not required. See an example of multiple combined syscalls:

    -a always,exit -F arch=b64 -S adjtimex -S settimeofday -k audit_time_rules

CCI-NaN
CCI-NaN

audit_rules_time_watch_localtime

unknown

Record Attempts to Alter the localtime File

Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited.

Add the following to `/etc/audit/audit.rules`:

    -w /etc/localtime -p wa -k audit_time_rules

The -k option allows for the specification of a key in string form that can be used for better reporting capability through ausearch and aureport and should always be used.

CCI-NaN
CCI-NaN

audit_rules_usergroup_modification

unknown

Record Events that Modify User/Group Information

In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications should be investigated for legitimacy.

Add the following to `/etc/audit/audit.rules`, in order to capture events that modify account changes:

    # audit_rules_usergroup_modification
    -w /etc/group -p wa -k audit_rules_usergroup_modification
    -w /etc/passwd -p wa -k audit_rules_usergroup_modification
    -w /etc/gshadow -p wa -k audit_rules_usergroup_modification
    -w /etc/shadow -p wa -k audit_rules_usergroup_modification
    -w /etc/security/opasswd -p wa -k audit_rules_usergroup_modification

CCI-NaN
CCI-NaN
CCI-NaN
CCI-NaN
CCI-NaN
CCI-NaN
CCI-NaN
CCI-NaN

audit_rules_networkconfig_modification

unknown

Record Events that Modify the System's Network Environment

The network environment should not be modified by anything other than administrator action. Any change to network parameters should be audited.

Add the following to `/etc/audit/audit.rules`, setting ARCH to either b32 or b64 as appropriate for your system:

    # audit_rules_networkconfig_modification
    -a always,exit -F arch=ARCH -S sethostname -S setdomainname -k audit_rules_networkconfig_modification
    -w /etc/issue -p wa -k audit_rules_networkconfig_modification
    -w /etc/issue.net -p wa -k audit_rules_networkconfig_modification
    -w /etc/hosts -p wa -k audit_rules_networkconfig_modification
    -w /etc/sysconfig/network -p wa -k audit_rules_networkconfig_modification

audit_rules_mac_modification

unknown

Record Events that Modify the System's Mandatory Access Controls

The system's mandatory access policy (SELinux) should not be arbitrarily changed by anything other than administrator action. All changes to MAC policy should be audited.

Add the following to `/etc/audit/audit.rules`:

    -w /etc/selinux/ -p wa -k MAC-policy

audit_rules_dac_modification_chmod

unknown

Record Events that Modify the System's Discretionary Access Controls - chmod

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.

At a minimum the audit system should collect file permission changes for all users and root. Add the following to `/etc/audit/audit.rules`:

    -a always,exit -F arch=b32 -S chmod -F auid>=500 -F auid!=4294967295 -k perm_mod

If the system is 64 bit then also add the following:

    -a always,exit -F arch=b64 -S chmod  -F auid>=500 -F auid!=4294967295 -k perm_mod

CCI-NaN

audit_rules_dac_modification_chown

unknown

Record Events that Modify the System's Discretionary Access Controls - chown

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.

At a minimum the audit system should collect file permission changes for all users and root. Add the following to `/etc/audit/audit.rules`:

    -a always,exit -F arch=b32 -S chown -F auid>=500 -F auid!=4294967295 -k perm_mod

If the system is 64 bit then also add the following:

    -a always,exit -F arch=b64 -S chown -F auid>=500 -F auid!=4294967295 -k perm_mod

CCI-NaN

audit_rules_dac_modification_fchmod

unknown

Record Events that Modify the System's Discretionary Access Controls - fchmod

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.

At a minimum the audit system should collect file permission changes for all users and root. Add the following to `/etc/audit/audit.rules`:

    -a always,exit -F arch=b32 -S fchmod -F auid>=500 -F auid!=4294967295 -k perm_mod

If the system is 64 bit then also add the following:

    -a always,exit -F arch=b64 -S fchmod -F auid>=500 -F auid!=4294967295 -k perm_mod

CCI-NaN

audit_rules_dac_modification_fchmodat

unknown

Record Events that Modify the System's Discretionary Access Controls - fchmodat

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.

At a minimum the audit system should collect file permission changes for all users and root. Add the following to `/etc/audit/audit.rules`:

    -a always,exit -F arch=b32 -S fchmodat -F auid>=500 -F auid!=4294967295 -k perm_mod

If the system is 64 bit then also add the following:

    -a always,exit -F arch=b64 -S fchmodat -F auid>=500 -F auid!=4294967295 -k perm_mod

CCI-NaN

audit_rules_dac_modification_fchown

unknown

Record Events that Modify the System's Discretionary Access Controls - fchown

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.

At a minimum the audit system should collect file permission changes for all users and root. Add the following to `/etc/audit/audit.rules`:

    -a always,exit -F arch=b32 -S fchown -F auid>=500 -F auid!=4294967295 -k perm_mod

If the system is 64 bit then also add the following:

    -a always,exit -F arch=b64 -S fchown -F auid>=500 -F auid!=4294967295 -k perm_mod

CCI-NaN

audit_rules_dac_modification_fchownat

unknown

Record Events that Modify the System's Discretionary Access Controls - fchownat

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.

At a minimum the audit system should collect file permission changes for all users and root. Add the following to `/etc/audit/audit.rules`:

    -a always,exit -F arch=b32 -S fchownat -F auid>=500 -F auid!=4294967295 -k perm_mod

If the system is 64 bit then also add the following:

    -a always,exit -F arch=b64 -S fchownat -F auid>=500 -F auid!=4294967295 -k perm_mod

CCI-NaN

audit_rules_dac_modification_fremovexattr

unknown

Record Events that Modify the System's Discretionary Access Controls - fremovexattr

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.

At a minimum the audit system should collect file permission changes for all users and root. Add the following to `/etc/audit/audit.rules`:

    -a always,exit -F arch=b32 -S fremovexattr -F auid>=500 -F auid!=4294967295 -k perm_mod

If the system is 64 bit then also add the following:

    -a always,exit -F arch=b64 -S fremovexattr -F auid>=500 -F auid!=4294967295 -k perm_mod

CCI-NaN

audit_rules_dac_modification_fsetxattr

unknown

Record Events that Modify the System's Discretionary Access Controls - fsetxattr

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.

At a minimum the audit system should collect file permission changes for all users and root. Add the following to `/etc/audit/audit.rules`:

    -a always,exit -F arch=b32 -S fsetxattr -F auid>=500 -F auid!=4294967295 -k perm_mod

If the system is 64 bit then also add the following:

    -a always,exit -F arch=b64 -S fsetxattr -F auid>=500 -F auid!=4294967295 -k perm_mod

CCI-NaN

audit_rules_dac_modification_lchown

unknown

Record Events that Modify the System's Discretionary Access Controls - lchown

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.

At a minimum the audit system should collect file permission changes for all users and root. Add the following to `/etc/audit/audit.rules`:

    -a always,exit -F arch=b32 -S lchown -F auid>=500 -F auid!=4294967295 -k perm_mod

If the system is 64 bit then also add the following:

    -a always,exit -F arch=b64 -S lchown -F auid>=500 -F auid!=4294967295 -k perm_mod

CCI-NaN

audit_rules_dac_modification_lremovexattr

unknown

Record Events that Modify the System's Discretionary Access Controls - lremovexattr

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.

At a minimum the audit system should collect file permission changes for all users and root. Add the following to `/etc/audit/audit.rules`:

    -a always,exit -F arch=b32 -S lremovexattr -F auid>=500 -F auid!=4294967295 -k perm_mod

If the system is 64 bit then also add the following:

    -a always,exit -F arch=b64 -S lremovexattr -F auid>=500 -F auid!=4294967295 -k perm_mod

CCI-NaN

audit_rules_dac_modification_lsetxattr

unknown

Record Events that Modify the System's Discretionary Access Controls - lsetxattr

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.

At a minimum the audit system should collect file permission changes for all users and root. Add the following to `/etc/audit/audit.rules`:

    -a always,exit -F arch=b32 -S lsetxattr -F auid>=500 -F auid!=4294967295 -k perm_mod

If the system is 64 bit then also add the following:

    -a always,exit -F arch=b64 -S lsetxattr -F auid>=500 -F auid!=4294967295 -k perm_mod

CCI-NaN

audit_rules_dac_modification_removexattr

unknown

Record Events that Modify the System's Discretionary Access Controls - removexattr

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.

At a minimum the audit system should collect file permission changes for all users and root. Add the following to `/etc/audit/audit.rules`:

    -a always,exit -F arch=b32 -S removexattr -F auid>=500 -F auid!=4294967295 -k perm_mod

If the system is 64 bit then also add the following:

    -a always,exit -F arch=b64 -S removexattr -F auid>=500 -F auid!=4294967295 -k perm_mod

CCI-NaN

audit_rules_dac_modification_setxattr

unknown

Record Events that Modify the System's Discretionary Access Controls - setxattr

The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users.

At a minimum the audit system should collect file permission changes for all users and root. Add the following to `/etc/audit/audit.rules`:

    -a always,exit -F arch=b32 -S setxattr -F auid>=500 -F auid!=4294967295 -k perm_mod

If the system is 64 bit then also add the following:

    -a always,exit -F arch=b64 -S setxattr -F auid>=500 -F auid!=4294967295 -k perm_mod

CCI-NaN

audit_rules_unsuccessful_file_modification

unknown

Ensure auditd Collects Unauthorized Access Attempts to Files (unsuccessful)

Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise.

At a minimum the audit system should collect unauthorized file accesses for all users and root. Add the following to `/etc/audit/audit.rules`:

    -a always,exit -F arch=b32 -S creat -S open -S openat -S open_by_handle_at -S truncate -S ftruncate -F exit=-EACCES -F auid>=500 -F auid!=4294967295 -k access
    -a always,exit -F arch=b32 -S creat -S open -S openat -S open_by_handle_at -S truncate -S ftruncate -F exit=-EPERM -F auid>=500 -F auid!=4294967295 -k access

If the system is 64 bit then also add the following:

    -a always,exit -F arch=b64 -S creat -S open -S openat -S open_by_handle_at -S truncate -S ftruncate -F exit=-EACCES -F auid>=500 -F auid!=4294967295 -k access
    -a always,exit -F arch=b64 -S creat -S open -S openat -S open_by_handle_at -S truncate -S ftruncate -F exit=-EPERM -F auid>=500 -F auid!=4294967295 -k access

CCI-NaN

audit_rules_privileged_commands

unknown

Ensure auditd Collects Information on the Use of Privileged Commands

Privileged programs are subject to escalation-of-privilege attacks, which attempt to subvert their normal role of providing some necessary but limited capability. As such, motivation exists to monitor these programs for unusual activity.

At a minimum the audit system should collect the execution of privileged commands for all users and root. To find the relevant setuid / setgid programs, run the following command for each local partition PART:

    $ sudo find PART -xdev -type f -perm -4000 -o -type f -perm -2000 2>/dev/null

Then, for each setuid / setgid program on the system, add a line of the following form to `/etc/audit/audit.rules`, where SETUID_PROG_PATH is the full path to each setuid / setgid program in the list:

    -a always,exit -F path=SETUID_PROG_PATH -F perm=x -F auid>=500 -F auid!=4294967295 -k privileged

CCI-NaN

audit_rules_media_export

unknown

Ensure auditd Collects Information on Exporting to Media (successful)

The unauthorized exportation of data to external media could result in an information leak where classified information, Privacy Act information, and intellectual property could be lost. An audit trail should be created each time a filesystem is mounted to help identify and guard against information loss.

At a minimum the audit system should collect media exportation events for all users and root. Add the following to `/etc/audit/audit.rules`, setting ARCH to either b32 or b64 as appropriate for your system:

    -a always,exit -F arch=ARCH -S mount -F auid>=500 -F auid!=4294967295 -k export

CCI-NaN

audit_rules_file_deletion_events

unknown

Ensure auditd Collects File Deletion Events by User

Auditing file deletions will create an audit trail for files that are removed from the system. The audit trail could aid in system troubleshooting, as well as, detecting malicious processes that attempt to delete log files to conceal their presence.

At a minimum the audit system should collect file deletion events for all users and root. Add the following to `/etc/audit/audit.rules`, setting ARCH to either b32 or b64 as appropriate for your system:

    -a always,exit -F arch=ARCH -S rmdir -S unlink -S unlinkat -S rename -S renameat -F auid>=500 -F auid!=4294967295 -k delete

CCI-NaN

audit_rules_sysadmin_actions

unknown

Ensure auditd Collects System Administrator Actions

The actions taken by system administrators should be audited to keep a record of what was executed on the system, as well as, for accountability purposes.

At a minimum the audit system should collect administrator actions for all users and root. Add the following to `/etc/audit/audit.rules`:

    -w /etc/sudoers -p wa -k actions

CCI-NaN

audit_rules_kernel_module_loading

unknown

Ensure auditd Collects Information on Kernel Module Loading and Unloading

The addition/removal of kernel modules can be used to alter the behavior of the kernel and potentially introduce malicious code into kernel space. It is important to have an audit trail of modules that have been introduced into the kernel.

Add the following to `/etc/audit/audit.rules` in order to capture kernel module loading and unloading events, setting ARCH to either b32 or b64 as appropriate for your system:

    -w /sbin/insmod -p x -k modules
    -w /sbin/rmmod -p x -k modules
    -w /sbin/modprobe -p x -k modules
    -a always,exit -F arch=ARCH -S init_module -S delete_module -k modules

CCI-NaN

service_xinetd_disabled

medium

Disable xinetd Service

The xinetd service provides a dedicated listener service for some programs, which is no longer necessary for commonly-used network services. Disabling it ensures that these uncommon services are not running, and also prevents attacks against xinetd itself.

The `xinetd` service can be disabled with the following command:

    $ sudo chkconfig xinetd off

CCI-NaN

package_xinetd_removed

unknown

Uninstall xinetd Package

Removing the `xinetd` package decreases the risk of the xinetd service's accidental (or intentional) activation.

The `xinetd` package can be uninstalled with the following command:

    $ sudo yum erase xinetd

CCI-NaN

package_telnet-server_removed

high

Uninstall telnet-server Package

Removing the `telnet-server` package decreases the risk of the telnet service's accidental (or intentional) activation.

The `telnet-server` package can be uninstalled with the following command:

    $ sudo yum erase telnet-server

CCI-NaN
CCI-NaN

service_telnetd_disabled

high

Disable telnet Service

The telnet protocol uses unencrypted network communication, which means that data from the login session, including passwords and all other information transmitted during the session, can be stolen by eavesdroppers on the network. The telnet protocol is also subject to man-in-the-middle attacks.

The `telnet` service can be disabled with the following command:

    $ sudo chkconfig telnet off

CCI-NaN
CCI-NaN
CCI-NaN
CCI-NaN
CCI-NaN

package_rsh-server_removed

high

Uninstall rsh-server Package

The `rsh-server` package provides several obsolete and insecure network services. Removing it decreases the risk of those services' accidental (or intentional) activation.

The `rsh-server` package can be uninstalled with the following command:

    $ sudo yum erase rsh-server

CCI-NaN
CCI-NaN

service_rsh_disabled

high

Disable rsh Service

The rsh service uses unencrypted network communications, which means that data from the login session, including passwords and all other information transmitted during the session, can be stolen by eavesdroppers on the network.

The `rsh` service, which is available with the `rsh-server` package and runs as a service through xinetd, should be disabled. The `rsh` service can be disabled with the following command:

    $ sudo chkconfig rsh off

CCI-NaN
CCI-NaN

service_rexec_disabled

high

Disable rexec Service

The rexec service uses unencrypted network communications, which means that data from the login session, including passwords and all other information transmitted during the session, can be stolen by eavesdroppers on the network.

The `rexec` service, which is available with the `rsh-server` package and runs as a service through xinetd, should be disabled. The `rexec` service can be disabled with the following command:

    $ sudo chkconfig rexec off

CCI-NaN
CCI-NaN

service_rlogin_disabled

high

Disable rlogin Service

The rlogin service uses unencrypted network communications, which means that data from the login session, including passwords and all other information transmitted during the session, can be stolen by eavesdroppers on the network.

The `rlogin` service, which is available with the `rsh-server` package and runs as a service through xinetd, should be disabled. The `rlogin` service can be disabled with the following command:

    $ sudo chkconfig rlogin off

CCI-NaN

package_ypserv_removed

medium

Uninstall ypserv Package

Removing the `ypserv` package decreases the risk of the accidental (or intentional) activation of NIS or NIS+ services.

The `ypserv` package can be uninstalled with the following command:

    $ sudo yum erase ypserv

CCI-NaN
CCI-NaN

service_ypbind_disabled

medium

Disable ypbind Service

Disabling the `ypbind` service ensures the system is not acting as a client in a NIS or NIS+ domain.

The `ypbind` service, which allows the system to act as a client in a NIS or NIS+ domain, should be disabled. The `ypbind` service can be disabled with the following command:

    $ sudo chkconfig ypbind off

CCI-NaN

package_tftp-server_removed

medium

Uninstall tftp-server Package

Removing the `tftp-server` package decreases the risk of the accidental (or intentional) activation of tftp services.

The `tftp-server` package can be removed with the following command:

    $ sudo yum erase tftp-server

CCI-NaN

service_tftp_disabled

medium

Disable tftp Service

Disabling the `tftp` service ensures the system is not acting as a TFTP server, which does not provide encryption or authentication.

The `tftp` service should be disabled. The `tftp` service can be disabled with the following command:

    $ sudo chkconfig tftp off

CCI-NaN

service_crond_enabled

medium

Enable cron Service

Due to its usage for maintenance and security-supporting tasks, enabling the cron daemon is essential.

The `crond` service is used to execute commands at preconfigured times. It is required by almost all systems to perform necessary maintenance tasks, such as notifying root of system activity. The `crond` service can be enabled with the following command:

    $ sudo chkconfig --level 2345 crond on

sshd_allow_only_protocol2

high

Allow Only SSH Protocol 2

SSH protocol version 1 suffers from design flaws that result in security vulnerabilities and should not be used.

Only SSH protocol version 2 connections should be permitted. The default setting in `/etc/ssh/sshd_config` is correct, and can be verified by ensuring that the following line appears:

    Protocol 2

CCI-NaN
CCI-NaN
CCI-NaN

sshd_set_idle_timeout

unknown

Set SSH Idle Timeout Interval

Causing idle users to be automatically logged out guards against compromises one system leading trivially to compromises on another.

SSH allows administrators to set an idle timeout interval. After this interval has passed, the idle user will be automatically logged out.
To set an idle timeout interval, edit the following line in `/etc/ssh/sshd_config` as follows:

    ClientAliveInterval

The timeout interval is given in seconds. To have a timeout of 15 minutes, set interval to 900.
If a shorter timeout has already been set for the login shell, that value will preempt any SSH setting made here. Keep in mind that some processes may stop SSH from correctly detecting that the user is idle.

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sshd_set_keepalive

unknown

Set SSH Client Alive Count

This ensures a user login will be terminated as soon as the `ClientAliveCountMax` is reached.

To ensure the SSH idle timeout occurs precisely when the `ClientAliveCountMax` is set, edit `/etc/ssh/sshd_config` as follows:

    ClientAliveCountMax 0

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sshd_disable_rhosts

medium

Disable SSH Support for .rhosts Files

SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts.

SSH can emulate the behavior of the obsolete rsh command in allowing users to enable insecure access to their accounts via `.rhosts` files.
To ensure this behavior is disabled, add or correct the following line in `/etc/ssh/sshd_config`:

    IgnoreRhosts yes

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disable_host_auth

medium

Disable Host-Based Authentication

SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts.

SSH's cryptographic host-based authentication is more secure than `.rhosts` authentication. However, it is not recommended that hosts unilaterally trust one another, even within an organization.
To disable host-based authentication, add or correct the following line in `/etc/ssh/sshd_config`:

    HostbasedAuthentication no

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sshd_disable_root_login

medium

Disable SSH Root Login

Permitting direct root login reduces auditable information about who ran privileged commands on the system and also allows direct attack attempts on root's password.

The root user should never be allowed to login to a system directly over a network. To disable root login via SSH, add or correct the following line in `/etc/ssh/sshd_config`:

    PermitRootLogin no

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sshd_disable_empty_passwords

high

Disable SSH Access via Empty Passwords

Configuring this setting for the SSH daemon provides additional assurance that remote login via SSH will require a password, even in the event of misconfiguration elsewhere.

To explicitly disallow remote login from accounts with empty passwords, add or correct the following line in `/etc/ssh/sshd_config`:

    PermitEmptyPasswords no

Any accounts with empty passwords should be disabled immediately, and PAM configuration should prevent users from being able to assign themselves empty passwords.

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sshd_enable_warning_banner

medium

Enable SSH Warning Banner

The warning message reinforces policy awareness during the login process and facilitates possible legal action against attackers. Alternatively, systems whose ownership should not be obvious should ensure usage of a banner that does not provide easy attribution.

To enable the warning banner and ensure it is consistent across the system, add or correct the following line in `/etc/ssh/sshd_config`:

    Banner /etc/issue

Another section contains information on how to create an appropriate system-wide warning banner.

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sshd_do_not_permit_user_env

unknown

Do Not Allow SSH Environment Options

SSH environment options potentially allow users to bypass access restriction in some configurations.

To ensure users are not able to present environment options to the SSH daemon, add or correct the following line in `/etc/ssh/sshd_config`:

    PermitUserEnvironment no

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sshd_use_approved_ciphers

medium

Use Only Approved Ciphers

Approved algorithms should impart some level of confidence in their implementation. These are also required for compliance.

Limit the ciphers to those algorithms which are FIPS-approved. Counter (CTR) mode is also preferred over cipher-block chaining (CBC) mode. The following line in `/etc/ssh/sshd_config` demonstrates use of FIPS-approved ciphers:

    Ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc,aes192-cbc,aes256-cbc

The man page `sshd_config(5)` contains a list of supported ciphers.

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service_avahi-daemon_disabled

unknown

Disable Avahi Server Software

Because the Avahi daemon service keeps an open network port, it is subject to network attacks. Its functionality is convenient but is only appropriate if the local network can be trusted.

The `avahi-daemon` service can be disabled with the following command:

    $ sudo chkconfig avahi-daemon off

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service_ntpd_enabled

medium

Enable the NTP Daemon

Enabling the `ntpd` service ensures that the `ntpd` service will be running and that the system will synchronize its time to any servers specified. This is important whether the system is configured to be a client (and synchronize only its own clock) or it is also acting as an NTP server to other systems. Synchronizing time is essential for authentication services such as Kerberos, but it is also important for maintaining accurate logs and auditing possible security breaches.
The NTP daemon offers all of the functionality of `ntpdate`, which is now deprecated. Additional information on this is available at http://support.ntp.org/bin/view/Dev/DeprecatingNtpdate

The `ntpd` service can be enabled with the following command:

    $ sudo chkconfig --level 2345 ntpd on

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ntpd_specify_remote_server

medium

Specify a Remote NTP Server

Synchronizing with an NTP server makes it possible to collate system logs from multiple sources or correlate computer events with real time events.

To specify a remote NTP server for time synchronization, edit the file `/etc/ntp.conf`. Add or correct the following lines, substituting the IP or hostname of a remote NTP server for ntpserver:

    server ntpserver

This instructs the NTP software to contact that remote server to obtain time data.

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postfix_network_listening_disabled

medium

Disable Postfix Network Listening

This ensures `postfix` accepts mail messages (such as cron job reports) from the local system only, and not from the network, which protects it from network attack.

Edit the file `/etc/postfix/main.cf` to ensure that only the following `inet_interfaces` line appears:

    inet_interfaces = localhost

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ldap_client_start_tls

medium

Configure LDAP Client to Use TLS For All Transactions

The ssl directive specifies whether to use ssl or not. If not specified it will default to no. It should be set to start_tls rather than doing LDAP over SSL.

Configure LDAP to enforce TLS use. First, edit the file `/etc/pam_ldap.conf`, and add or correct the following lines:

    ssl start_tls

Then review the LDAP server and ensure TLS has been configured.

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ldap_client_tls_cacertpath

medium

Configure Certificate Directives for LDAP Use of TLS

The tls_cacertdir or tls_cacertfile directives are required when tls_checkpeer is configured (which is the default for openldap versions 2.1 and up). These directives define the path to the trust certificates signed by the site CA.

Ensure a copy of a trusted CA certificate has been placed in the file `/etc/pki/tls/CA/cacert.pem`. Configure LDAP to enforce TLS use and to trust certificates signed by that CA. First, edit the file `/etc/pam_ldap.conf`, and add or correct either of the following lines:

    tls_cacertdir /etc/pki/tls/CA

or

    tls_cacertfile /etc/pki/tls/CA/cacert.pem

Then review the LDAP server and ensure TLS has been configured.

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package_openldap-servers_removed

unknown

Uninstall openldap-servers Package

The `openldap-servers` package is not installed by default on RHEL6 systems. It is needed only by the OpenLDAP server system, not clients which use LDAP for authentication. If the system is not intended for use as an LDAP server, `openldap-servers` should be removed.

The `openldap-servers` package should be removed if not in use. Is this system the OpenLDAP server? If not, remove the package.

    $ sudo yum erase openldap-servers

The openldap-servers RPM is not installed by default on Red Hat Enterprise Linux 6 systems. It is needed only by the OpenLDAP server, not by the clients which use LDAP for authentication. If the system is not intended for use as an LDAP Server it should be removed.

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gconf_gnome_screensaver_idle_delay

medium

Set GNOME Login Inactivity Timeout

Setting the idle delay controls when the screensaver will start, and can be combined with screen locking to prevent access from passersby.

Run the following command to set the idle time-out value for inactivity in the GNOME desktop to minutes:

    $ sudo gconftool-2 \
      --direct \
      --config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory \
      --type int \
      --set /desktop/gnome/session/idle_delay

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accounts_tmout | unknown | Set Interactive Session Timeout |  | Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. |  |  |  |

gconf_gnome_screensaver_idle_activation_enabled

medium

GNOME Desktop Screensaver Mandatory Use

Enabling idle activation of the screensaver ensures the screensaver will be activated after the idle delay. Applications requiring continuous, real-time screen display (such as network management products) require the login session does not have administrator rights and the display station is located in a controlled-access area.

Run the following command to activate the screensaver in the GNOME desktop after a period of inactivity:

    $ sudo gconftool-2 --direct \
      --config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory \
      --type bool \
      --set /apps/gnome-screensaver/idle_activation_enabled true

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gconf_gnome_screensaver_lock_enabled

medium

Enable Screen Lock Activation After Idle Period

Enabling the activation of the screen lock after an idle period ensures password entry will be required in order to access the system, preventing access by passersby.

Run the following command to activate locking of the screensaver in the GNOME desktop when it is activated:

    $ sudo gconftool-2 --direct \
      --config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory \
      --type bool \
      --set /apps/gnome-screensaver/lock_enabled true

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gconf_gnome_screensaver_mode_blank

unknown

Implement Blank Screensaver

Setting the screensaver mode to blank-only conceals the contents of the display from passersby.

Run the following command to set the screensaver mode in the GNOME desktop to a blank screen:

    $ sudo gconftool-2 --direct \
      --config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory \
      --type string \
      --set /apps/gnome-screensaver/mode blank-only

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service_abrtd_disabled

unknown

Disable Automatic Bug Reporting Tool (abrtd)

Mishandling crash data could expose sensitive information about vulnerabilities in software executing on the local system, as well as sensitive information from within a process's address space or registers.

The Automatic Bug Reporting Tool (`abrtd`) daemon collects and reports crash data when an application crash is detected. Using a variety of plugins, abrtd can email crash reports to system administrators, log crash reports to files, or forward crash reports to a centralized issue tracking system such as RHTSupport. The `abrtd` service can be disabled with the following command:

    $ sudo chkconfig abrtd off

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service_autofs_disabled

low

Disable the Automounter

Disabling the automounter permits the administrator to statically control filesystem mounting through `/etc/fstab`.

The `autofs` daemon mounts and unmounts filesystems, such as user home directories shared via NFS, on demand. In addition, autofs can be used to handle removable media, and the default configuration provides the cdrom device as `/misc/cd`. However, this method of providing access to removable media is not common, so autofs can almost always be disabled if NFS is not in use. Even if NFS is required, it may be possible to configure filesystem mounts statically by editing `/etc/fstab` rather than relying on the automounter.
The `autofs` service can be disabled with the following command:

    $ sudo chkconfig autofs off

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service_ntpdate_disabled

unknown

Disable ntpdate Service (ntpdate)

The `ntpdate` service may only be suitable for systems which are rebooted frequently enough that clock drift does not cause problems between reboots. In any event, the functionality of the ntpdate service is now available in the ntpd program and should be considered deprecated.

The `ntpdate` service sets the local hardware clock by polling NTP servers when the system boots. It synchronizes to the NTP servers listed in `/etc/ntp/step-tickers` or `/etc/ntp.conf` and then sets the local hardware clock to the newly synchronized system time. The `ntpdate` service can be disabled with the following command:

    $ sudo chkconfig ntpdate off

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service_oddjobd_disabled

unknown

Disable Odd Job Daemon (oddjobd)

The `oddjobd` service may provide necessary functionality in some environments, and can be disabled if it is not needed. Execution of tasks by privileged programs, on behalf of unprivileged ones, has traditionally been a source of privilege escalation security issues.

The `oddjobd` service exists to provide an interface and access control mechanism through which specified privileged tasks can run tasks for unprivileged client applications. Communication with `oddjobd` through the system message bus. The `oddjobd` service can be disabled with the following command:

    $ sudo chkconfig oddjobd off

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service_qpidd_disabled

unknown

Disable Apache Qpid (qpidd)

The qpidd service is automatically installed when the "base" package selection is selected during installation. The qpidd service listens for network connections, which increases the attack surface of the system. If the system is not intended to receive AMQP traffic, then the `qpidd` service is not needed and should be disabled or removed.

The `qpidd` service provides high speed, secure, guaranteed delivery services. It is an implementation of the Advanced Message Queuing Protocol. By default the qpidd service will bind to port 5672 and listen for connection attempts. The `qpidd` service can be disabled with the following command:

    $ sudo chkconfig qpidd off

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service_rdisc_disabled

unknown

Disable Network Router Discovery Daemon (rdisc)

General-purpose systems typically have their network and routing information configured statically by a system administrator. Workstations or some special-purpose systems often use DHCP (instead of IRDP) to retrieve dynamic network configuration information.

The `rdisc` service implements the client side of the ICMP Internet Router Discovery Protocol (IRDP), which allows discovery of routers on the local subnet. If a router is discovered then the local routing table is updated with a corresponding default route. By default this daemon is disabled. The `rdisc` service can be disabled with the following command:

    $ sudo chkconfig rdisc off

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mount_option_nodev_remote_filesystems | medium | Mount Remote Filesystems with nodev | Legitimate device files should only exist in the /dev directory. NFS mounts should not present device files to users. | Add the `nodev` option to the fourth column of `/etc/fstab` for the line which controls mounting of any NFS mounts. |  |  |  |
mount_option_nosuid_remote_filesystems | medium | Mount Remote Filesystems with nosuid | NFS mounts should not present suid binaries to users. Only vendor-supplied suid executables should be installed to their default location on the local filesystem. | Add the `nosuid` option to the fourth column of `/etc/fstab` for the line which controls mounting of any NFS mounts. |  |  |  |

require_smb_client_signing

unknown

Require Client SMB Packet Signing, if using smbclient

Packet signing can prevent man-in-the-middle attacks which modify SMB packets in transit.

To require samba clients running `smbclient` to use packet signing, add the following to the `[global]` section of the Samba configuration file, `/etc/samba/smb.conf`:

    client signing = mandatory

Requiring samba clients such as `smbclient` to use packet signing ensures they can only communicate with servers that support packet signing.

mount_option_smb_client_signing

unknown

Require Client SMB Packet Signing, if using mount.cifs

Packet signing can prevent man-in-the-middle attacks which modify SMB packets in transit.

Require packet signing of clients who mount Samba shares using the `mount.cifs` program (e.g., those who specify shares in `/etc/fstab`). To do so, ensure signing options (either `sec=krb5i` or `sec=ntlmv2i`) are used.
See the `mount.cifs(8)` man page for more information. A Samba client should only communicate with servers who can support SMB packet signing.

encrypt_partitions

unknown

Encrypt Partitions

The risk of a system's physical compromise, particularly mobile systems such as laptops, places its data at risk of compromise. Encrypting this data mitigates the risk of its loss if the system is lost.

Red Hat Enterprise Linux 6 natively supports partition encryption through the Linux Unified Key Setup-on-disk-format (LUKS) technology. The easiest way to encrypt a partition is during installation time.
For manual installations, select the `Encrypt` checkbox during partition creation to encrypt the partition. When this option is selected the system will prompt for a passphrase to use in decrypting the partition. The passphrase will subsequently need to be entered manually every time the system boots.
For automated/unattended installations, it is possible to use Kickstart by adding the `--encrypted` and `--passphrase=` options to the definition of each partition to be encrypted. For example, the following line would encrypt the root partition:

    part / --fstype=ext3 --size=100 --onpart=hda1 --encrypted --passphrase=PASSPHRASE

Any PASSPHRASE is stored in the Kickstart in plaintext, and the Kickstart must then be protected accordingly. Omitting the `--passphrase=` option from the partition definition will cause the installer to pause and interactively ask for the passphrase during installation.
By default, the `Anaconda` installer uses `aes-xts-plain64` cipher with a minimum `512` bit key size which should be compatible with FIPS enabled.
Detailed information on encrypting partitions using LUKS or LUKS ciphers can be found on the Red Hat Documentation web site:
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Security_Guide/chap-Security_Guide-Encryption.html#sect-Security_Guide-LUKS_Disk_Encryption

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kernel_disable_entropy_contribution_for_solid_state_drives

medium

Ensure Solid State Drives Do Not Contribute To Random-Number Entropy Pool

In contrast to traditional electromechanical magnetic disks, containing spinning disks and / or movable read / write heads, the solid-state storage devices (SSDs) do not contain moving / mechanical components. Therefore the I/O operation completion times are much more predictable for them.

For each solid-state drive on the system, run:

     # echo 0 > /sys/block/DRIVE/queue/add_random

rpm_verify_permissions

unknown

Verify and Correct File Permissions with RPM

Permissions on system binaries and configuration files that are too generous could allow an unauthorized user to gain privileges that they should not have. The permissions set by the vendor should be maintained. Any deviations from this baseline should be investigated.

The RPM package management system can check file access permissions of installed software packages, including many that are important to system security. After locating a file with incorrect permissions which can be found with

    $ rpm -Va | grep '^.M'

, run the following command to determine which package owns it:

    $ rpm -qf FILENAME

Next, run the following command to reset its permissions to the correct values:

    $ sudo rpm --setperms PACKAGENAME

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rpm_verify_hashes

unknown

Verify File Hashes with RPM

The hashes of important files like system executables should match the information given by the RPM database. Executables with erroneous hashes could be a sign of nefarious activity on the system.

The RPM package management system can check the hashes of installed software packages, including many that are important to system security. Run the following command to list which files on the system have hashes that differ from what is expected by the RPM database:

    $ rpm -Va | grep '^..5'

A "c" in the second column indicates that a file is a configuration file, which may appropriately be expected to change. If the file was not expected to change, investigate the cause of the change using audit logs or other means. The package can then be reinstalled to restore the file. Run the following command to determine which package owns the file:

    $ rpm -qf FILENAME

The package can be reinstalled from a yum repository using the command:

    $ sudo yum reinstall PACKAGENAME

Alternatively, the package can be reinstalled from trusted media using the command:

    $ sudo rpm -Uvh PACKAGENAME

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mount_option_nodev_removable_partitions

unknown

Add nodev Option to Removable Media Partitions

The only legitimate location for device files is the `/dev` directory located on the root partition. An exception to this is chroot jails, and it is not advised to set `nodev` on partitions which contain their root filesystems.

The `nodev` mount option prevents files from being interpreted as character or block devices. Legitimate character and block devices should exist only in the `/dev` directory on the root partition or within chroot jails built for system services. Add the `nodev` option to the fourth column of `/etc/fstab` for the line which controls mounting of any removable media partitions.

mount_option_noexec_removable_partitions

unknown

Add noexec Option to Removable Media Partitions

Allowing users to execute binaries from removable media such as USB keys exposes the system to potential compromise.

The `noexec` mount option prevents the direct execution of binaries on the mounted filesystem. Preventing the direct execution of binaries from removable media (such as a USB key) provides a defense against malicious software that may be present on such untrusted media. Add the `noexec` option to the fourth column of `/etc/fstab` for the line which controls mounting of any removable media partitions.

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mount_option_nosuid_removable_partitions

unknown

Add nosuid Option to Removable Media Partitions

The presence of SUID and SGID executables should be tightly controlled. Allowing users to introduce SUID or SGID binaries from partitions mounted off of removable media would allow them to introduce their own highly-privileged programs.

The `nosuid` mount option prevents set-user-identifier (SUID) and set-group-identifier (SGID) permissions from taking effect. These permissions allow users to execute binaries with the same permissions as the owner and group of the file respectively. Users should not be allowed to introduce SUID and SGID files into the system via partitions mounted from removeable media. Add the `nosuid` option to the fourth column of `/etc/fstab` for the line which controls mounting of any removable media partitions.

mount_option_dev_shm_nodev

unknown

Add nodev Option to /dev/shm

The only legitimate location for device files is the `/dev` directory located on the root partition. The only exception to this is chroot jails.

The `nodev` mount option can be used to prevent creation of device files in `/dev/shm`. Legitimate character and block devices should not exist within temporary directories like `/dev/shm`. Add the `nodev` option to the fourth column of `/etc/fstab` for the line which controls mounting of `/dev/shm`.

mount_option_dev_shm_nosuid

unknown

Add nosuid Option to /dev/shm

The presence of SUID and SGID executables should be tightly controlled. Users should not be able to execute SUID or SGID binaries from temporary storage partitions.

The `nosuid` mount option can be used to prevent execution of setuid programs in `/dev/shm`. The SUID and SGID permissions should not be required in these world-writable directories. Add the `nosuid` option to the fourth column of `/etc/fstab` for the line which controls mounting of `/dev/shm`.

mount_option_dev_shm_noexec

unknown

Add noexec Option to /dev/shm

Allowing users to execute binaries from world-writable directories such as `/dev/shm` can expose the system to potential compromise.

The `noexec` mount option can be used to prevent binaries from being executed out of `/dev/shm`. It can be dangerous to allow the execution of binaries from world-writable temporary storage directories such as `/dev/shm`. Add the `noexec` option to the fourth column of `/etc/fstab` for the line which controls mounting of `/dev/shm`.

mount_option_tmp_noexec

unknown

Add noexec Option to /tmp

Allowing users to execute binaries from world-writable directories such as `/tmp` should never be necessary in normal operation and can expose the system to potential compromise.

The `noexec` mount option can be used to prevent binaries from being executed out of `/tmp`. Add the `noexec` option to the fourth column of `/etc/fstab` for the line which controls mounting of `/tmp`.

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file_permissions_unauthorized_world_writable

medium

Ensure No World-Writable Files Exist

Data in world-writable files can be modified by any user on the system. In almost all circumstances, files can be configured using a combination of user and group permissions to support whatever legitimate access is needed without the risk caused by world-writable files.

It is generally a good idea to remove global (other) write access to a file when it is discovered. However, check with documentation for specific applications before making changes. Also, monitor for recurring world-writable files, as these may be symptoms of a misconfigured application or user account. Finally, this applies to real files and not virtual files that are a part of pseudo file systems such as `sysfs` or `procfs`.

install_antivirus

unknown

Install Virus Scanning Software

Virus scanning software can be used to detect if a system has been compromised by computer viruses, as well as to limit their spread to other systems.

Install virus scanning software, which uses signatures to search for the presence of viruses on the filesystem. The McAfee VirusScan Enterprise for Linux virus scanning tool is provided for DoD systems. Ensure virus definition files are no older than 7 days, or their last release. Configure the virus scanning software to perform scans dynamically on all accessed files. If this is not possible, configure the system to scan all altered files on the system on a daily basis. If the system processes inbound SMTP mail, configure the virus scanner to scan all received mail.

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install_hids

medium

Install Intrusion Detection Software

Host-based intrusion detection tools provide a system-level defense when an intruder gains access to a system or network.

The base Red Hat platform already includes a sophisticated auditing system that can detect intruder activity, as well as SELinux, which provides host-based intrusion prevention capabilities by confining privileged programs and user sessions which may become compromised.
In DoD environments, supplemental intrusion detection tools, such as, the McAfee Host-based Security System, are available to integrate with existing infrastructure. When these supplemental tools interfere with the proper functioning of SELinux, SELinux takes precedence.

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disable_ctrlaltdel_reboot

high

Disable Ctrl-Alt-Del Reboot Activation

A locally logged-in user who presses Ctrl-Alt-Del, when at the console, can reboot the system. If accidentally pressed, as could happen in the case of mixed OS environment, this can create the risk of short-term loss of availability of systems due to unintentional reboot. In the GNOME graphical environment, risk of unintentional reboot from the Ctrl-Alt-Del sequence is reduced because the user will be prompted before any action is taken. NOTE: When updating the `initscripts` package on a Red Hat Enterprise Linux 6 system, custom changes to `/etc/init/control-alt-delete.conf` may be overwritten. Refer to https://access.redhat.com/site/solutions/70464 for additional information.

By default, the system includes the following line in `/etc/init/control-alt-delete.conf` to reboot the system when the Ctrl-Alt-Del key sequence is pressed:

    exec /sbin/shutdown -r now "Control-Alt-Delete pressed"

To configure the system to log a message instead of rebooting the system, alter that line to read as follows:

    exec /usr/bin/logger -p security.info "Control-Alt-Delete pressed"

service_postfix_enabled

unknown

Enable Postfix Service

Local mail delivery is essential to some system maintenance and notification tasks.

The Postfix mail transfer agent is used for local mail delivery within the system. The default configuration only listens for connections to the default SMTP port (port 25) on the loopback interface (127.0.0.1). It is recommended to leave this service enabled for local mail delivery. The `postfix` service can be enabled with the following command:

    $ sudo chkconfig --level 2345 postfix on

package_sendmail_removed

medium

Uninstall Sendmail Package

The sendmail software was not developed with security in mind and its design prevents it from being effectively contained by SELinux. Postfix should be used instead.

Sendmail is not the default mail transfer agent and is not installed by default. The `sendmail` package can be removed with the following command:

    $ sudo yum erase sendmail

service_netconsole_disabled

unknown

Disable Network Console (netconsole)

The `netconsole` service is not necessary unless there is a need to debug kernel panics, which is not common.

The `netconsole` service is responsible for loading the netconsole kernel module, which logs kernel printk messages over UDP to a syslog server. This allows debugging of problems where disk logging fails and serial consoles are impractical. The `netconsole` service can be disabled with the following command:

    $ sudo chkconfig netconsole off

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service_atd_disabled

unknown

Disable At Service (atd)

The `atd` service could be used by an unsophisticated insider to carry out activities outside of a normal login session, which could complicate accountability. Furthermore, the need to schedule tasks with `at` or `batch` is not common.

The `at` and `batch` commands can be used to schedule tasks that are meant to be executed only once. This allows delayed execution in a manner similar to cron, except that it is not recurring. The daemon `atd` keeps track of tasks scheduled via `at` and `batch`, and executes them at the specified time. The `atd` service can be disabled with the following command:

    $ sudo chkconfig atd off

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xwindows_runlevel_setting

unknown

Disable X Windows Startup By Setting Runlevel

Unnecessary services should be disabled to decrease the attack surface of the system.

Setting the system's runlevel to 3 will prevent automatic startup of the X server. To do so, ensure the following line in `/etc/inittab` features a `3` as shown:

    id:3:initdefault:

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package_xorg-x11-server-common_removed

unknown

Remove the X Windows Package Group

Unnecessary packages should not be installed to decrease the attack surface of the system.

Removing all packages which constitute the X Window System ensures users or malicious software cannot start X. To do so, run the following command:

    $ sudo yum groupremove "X Window System"

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sysconfig_networking_bootproto_ifcfg

unknown

Disable DHCP Client

DHCP relies on trusting the local network. If the local network is not trusted, then it should not be used. However, the automatic configuration provided by DHCP is commonly used and the alternative, manual configuration, presents an unacceptable burden in many circumstances.

For each interface on the system (e.g. eth0), edit `/etc/sysconfig/network-scripts/ifcfg-interface` and make the following changes:

- Correct the BOOTPROTO line to read:

      BOOTPROTO=none

- Add or correct the following lines, substituting the appropriate values based on your site's addressing scheme:

      NETMASK=255.255.255.0
      IPADDR=192.168.1.2
      GATEWAY=192.168.1.1

CCI-NaN

accounts_password_pam_unix_remember

medium

Limit Password Reuse

Preventing re-use of previous passwords helps ensure that a compromised password is not re-used by a user.

Do not allow users to reuse recent passwords. This can be accomplished by using the `remember` option for the `pam_unix` or `pam_pwhistory` PAM modules. In the file `/etc/pam.d/system-auth`, append `remember=` to the line which refers to the `pam_unix.so` or `pam_pwhistory.so`module, as shown below:

- for the `pam_unix.so` case:

      password sufficient pam_unix.so existing_options remember=

- for the `pam_pwhistory.so` case:

      password requisite pam_pwhistory.so existing_options remember=

The DoD STIG requirement is 5 passwords.

CCI-NaN

gid_passwd_group_same | unknown | All GIDs referenced in /etc/passwd must be defined in /etc/group | Inconsistency in GIDs between `/etc/passwd` and `/etc/group` could lead to a user having unintended rights. | Add a group to the system for each GID referenced without a corresponding group. |  |  | CCI-NaN |
account_unique_name | unknown | Ensure All Accounts on the System Have Unique Names | Unique usernames allow for accountability on the system. | Change usernames, or delete accounts, so each has a unique name. |  |  | CCI-NaN CCI-NaN |

account_temp_expire_date

unknown

Assign Expiration Date to Temporary Accounts

When temporary and emergency accounts are created, there is a risk they may remain in place and active after the need for them no longer exists. Account expiration greatly reduces the risk of accounts being misused or hijacked.

In the event temporary or emergency accounts are required, configure the system to terminate them after a documented time period. For every temporary and emergency account, run the following command to set an expiration date on it, substituting `USER` and `YYYY-MM-DD` appropriately:

    $ sudo chage -E YYYY-MM-DD USER

`YYYY-MM-DD` indicates the documented expiration date for the account.

CCI-NaN
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accounts_password_pam_maxrepeat

unknown

Set Password to Maximum of Three Consecutive Repeating Characters

Passwords with excessive repeating characters may be more vulnerable to password-guessing attacks.

The pam_cracklib module's `maxrepeat` parameter controls requirements for consecutive repeating characters. When set to a positive number, it will reject passwords which contain more than that number of consecutive characters. Add `maxrepeat=` after pam_cracklib.so to prevent a run of ( + 1) or more identical characters:

    password required pam_cracklib.so maxrepeat=

CCI-NaN

no_files_unowned_by_user

unknown

Ensure All Files Are Owned by a User

Unowned files do not directly imply a security problem, but they are generally a sign that something is amiss. They may be caused by an intruder, by incorrect software installation or draft software removal, or by failure to remove all files belonging to a deleted account. The files should be repaired so they will not cause problems when accounts are created in the future, and the cause should be discovered and addressed.

If any files are not owned by a user, then the cause of their lack of ownership should be investigated. Following this, the files should be deleted or assigned to an appropriate user.

CCI-NaN

file_permissions_ungroupowned

unknown

Ensure All Files Are Owned by a Group

Unowned files do not directly imply a security problem, but they are generally a sign that something is amiss. They may be caused by an intruder, by incorrect software installation or draft software removal, or by failure to remove all files belonging to a deleted account. The files should be repaired so they will not cause problems when accounts are created in the future, and the cause should be discovered and addressed.

If any files are not owned by a group, then the cause of their lack of group-ownership should be investigated. Following this, the files should be deleted or assigned to an appropriate group.

CCI-NaN

aide_periodic_cron_checking

medium

Configure Periodic Execution of AIDE

By default, AIDE does not install itself for periodic execution. Periodically running AIDE is necessary to reveal unexpected changes in installed files.

To implement a daily execution of AIDE at 4:05am using cron, add the following line to `/etc/crontab`:

    05 4 * * * root /usr/sbin/aide --check

AIDE can be executed periodically through other means; this is merely one example.

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disable_users_coredumps

unknown

Disable Core Dumps for All Users

A core dump includes a memory image taken at the time the operating system terminates an application. The memory image could contain sensitive data and is generally useful only for developers trying to debug problems.

To disable core dumps for all users, add the following line to `/etc/security/limits.conf`:

    *     hard   core    0

no_insecure_locks_exports

high

Ensure Insecure File Locking is Not Allowed

Allowing insecure file locking could allow for sensitive data to be viewed or edited by an unauthorized user.

By default the NFS server requires secure file-lock requests, which require credentials from the client in order to lock a file. Most NFS clients send credentials with file lock requests, however, there are a few clients that do not send credentials when requesting a file-lock, allowing the client to only be able to lock world-readable files. To get around this, the `insecure_locks` option can be used so these clients can access the desired export. This poses a security risk by potentially allowing the client access to data for which it does not have authorization. Remove any instances of the `insecure_locks` option from the file `/etc/exports`.

CCI-NaN

auditd_data_retention_space_left_action

medium

Configure auditd space_left Action on Low Disk Space

Notifying administrators of an impending disk space problem may allow them to take corrective action prior to any disruption.

The `auditd` service can be configured to take an action when disk space starts to run low. Edit the file `/etc/audit/auditd.conf`. Modify the following line, substituting ACTION appropriately:

    space_left_action = ACTION

Possible values for ACTION are described in the `auditd.conf` man page. These include:

- `ignore`
- `syslog`
- `email`
- `exec`
- `suspend`
- `single`
- `halt`

Set this to `email` (instead of the default, which is `suspend`) as it is more likely to get prompt attention. Acceptable values also include `suspend`, `single`, and `halt`.

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auditd_data_retention_action_mail_acct

medium

Configure auditd mail_acct Action on Low Disk Space

Email sent to the root account is typically aliased to the administrators of the system, who can take appropriate action.

The `auditd` service can be configured to send email to a designated account in certain situations. Add or correct the following line in `/etc/audit/auditd.conf` to ensure that administrators are notified via email for those situations:

    action_mail_acct =

CCI-NaN
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gconf_gnome_screen_locking_keybindings

low

Set GNOME Screen Locking Keybindings

The ability to lock graphical desktop sessions manually allows users to easily secure their accounts should they need to depart from their workstations temporarily.

Run the following command to prevent changes to the screensaver lock keybindings:

    $ sudo gconftool-2 --direct \
      --config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory \
      --type string \
      --set /apps/gnome_settings_daemon/keybindings/screensaver "<Control><Alt>l"

CCI-NaN

no_all_squash_exports

low

Ensure All-Squashing Disabled On All Exports

The all_squash option maps all client requests to a single anonymous uid/gid on the NFS server, negating the ability to track file access by user ID.

The `all_squash` maps all uids and gids to an anonymous user. This should be disabled by removing any instances of the `all_squash` option from the file `/etc/exports`.

CCI-NaN

sshd_print_last_log

medium

Print Last Log

Providing users feedback on when account accesses last occurred facilitates user recognition and reporting of unauthorized account use.

When enabled, SSH will display the date and time of the last successful account logon. To enable LastLog in SSH, add or correct the following line in the `/etc/ssh/sshd_config` file:

    PrintLastLog yes

CCI-NaN

auditd_data_retention_space_left

medium

Configure auditd space_left on Low Disk Space

Notifying administrators of an impending disk space problem may allow them to take corrective action prior to any disruption.

The `auditd` service can be configured to take an action when disk space is running low but prior to running out of space completely. Edit the file `/etc/audit/auditd.conf`. Add or modify the following line, substituting SIZE_in_MB appropriately:

    space_left = SIZE_in_MB

Set this value to the appropriate size in Megabytes cause the system to notify the user of an issue.

CCI-NaN

auditd_data_disk_full_action

medium

Configure auditd Disk Full Action when Disk Space Is Full

Taking appropriate action in case of a filled audit storage volume will minimize the possibility of losing audit records.

The `auditd` service can be configured to take an action when disk space is running low but prior to running out of space completely. Edit the file `/etc/audit/auditd.conf`. Add or modify the following line, substituting ACTION appropriately:

    disk_full_action = ACTION

Set this value to `single` to cause the system to switch to single-user mode for corrective action. Acceptable values also include `syslog`, `exec`, `single`, and `halt`. For certain systems, the need for availability outweighs the need to log all actions, and a different setting should be determined. Details regarding all possible values for ACTION are described in the `auditd.conf` man page.

CCI-NaN

auditd_data_disk_error_action

medium

Configure auditd Disk Error Action on Disk Error

Taking appropriate action in case of disk errors will minimize the possibility of losing audit records.

The `auditd` service can be configured to take an action when there is a disk error. Edit the file `/etc/audit/auditd.conf`. Add or modify the following line, substituting ACTION appropriately:

    disk_error_action = ACTION

Set this value to `single` to cause the system to switch to single-user mode for corrective action. Acceptable values also include `syslog`, `exec`, `single`, and `halt`. For certain systems, the need for availability outweighs the need to log all actions, and a different setting should be determined. Details regarding all possible values for ACTION are described in the `auditd.conf` man page.

CCI-NaN

directory_permissions_var_log_audit

unknown

System Audit Logs Must Have Mode 0750 or Less Permissive

If users can write to audit logs, audit trails can be modified or destroyed.

If `log_group` in `/etc/audit/auditd.conf` is set to a group other than the `root` group account, change the mode of the audit log files with the following command:

    $ sudo chmod 0750 /var/log/audit

Otherwise, change the mode of the audit log files with the following command:

    $ sudo chmod 0700 /var/log/audit

CCI-NaN

rpm_verify_ownership

unknown

Verify and Correct Ownership with RPM

Ownership of binaries and configuration files that is incorrect could allow an unauthorized user to gain privileges that they should not have. The ownership set by the vendor should be maintained. Any deviations from this baseline should be investigated.

The RPM package management system can check file ownership permissions of installed software packages, including many that are important to system security. After locating a file with incorrect permissions, which can be found with

    rpm -Va | grep "^.....\(U\|.G\)"

run the following command to determine which package owns it:

    $ rpm -qf FILENAME

Next, run the following command to reset its permissions to the correct values:

    $ sudo rpm --setugids PACKAGENAME

CCI-NaN

kernel_module_bluetooth_disabled

medium

Disable Bluetooth Kernel Modules

If Bluetooth functionality must be disabled, preventing the kernel from loading the kernel module provides an additional safeguard against its activation.

The kernel's module loading system can be configured to prevent loading of the Bluetooth module. Add the following to the appropriate `/etc/modprobe.d` configuration file to prevent the loading of the Bluetooth module:

    install bluetooth /bin/true

CCI-NaN
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kernel_module_usb-storage_disabled

unknown

Disable Modprobe Loading of USB Storage Driver

USB storage devices such as thumb drives can be used to introduce malicious software.

To prevent USB storage devices from being used, configure the kernel module loading system to prevent automatic loading of the USB storage driver. To configure the system to prevent the `usb-storage` kernel module from being loaded, add the following line to a file in the directory `/etc/modprobe.d`:

    install usb-storage /bin/true

This will prevent the `modprobe` program from loading the `usb-storage` module, but will not prevent an administrator (or another program) from using the `insmod` program to load the module manually.

CCI-NaN
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accounts_max_concurrent_login_sessions

unknown

Limit the Number of Concurrent Login Sessions Allowed Per User

Limiting simultaneous user logins can insulate the system from denial of service problems caused by excessive logins. Automated login processes operating improperly or maliciously may result in an exceptional number of simultaneous login sessions.

Limiting the number of allowed users and sessions per user can limit risks related to Denial of Service attacks. This addresses concurrent sessions for a single account and does not address concurrent sessions by a single user via multiple accounts. The DoD requirement is 10. To set the number of concurrent sessions per user add the following line in `/etc/security/limits.conf`:

    * hard maxlogins

CCI-NaN

set_iptables_default_rule_forward

medium

Set Default iptables Policy for Forwarded Packets

In `iptables`, the default policy is applied only after all the applicable rules in the table are examined for a match. Setting the default policy to `DROP` implements proper design for a firewall, i.e. any packets which are not explicitly permitted should not be accepted.

To set the default policy to DROP (instead of ACCEPT) for the built-in FORWARD chain which processes packets that will be forwarded from one interface to another, add or correct the following line in `/etc/sysconfig/iptables`:

    :FORWARD DROP [0:0]

CCI-NaN

package_openswan_installed

unknown

Install openswan or libreswan Package

Providing the ability for remote users or systems to initiate a secure VPN connection protects information when it is transmitted over a wide area network.

The openswan and libreswan packages provide an implementation of IPsec and IKE, which permits the creation of secure tunnels over untrusted networks. The `openswan` package can be installed with the following command:

    $ sudo yum install openswan

The `libreswan` package can be installed with the following command:

    $ sudo yum install libreswan

CCI-NaN
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gconf_gdm_enable_warning_gui_banner

medium

Enable GUI Warning Banner

An appropriate warning message reinforces policy awareness during the login process and facilitates possible legal action against attackers.

To enable displaying a login warning banner in the GNOME Display Manager's login screen, run the following command:

    $ sudo gconftool-2 --direct \
      --config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory \
      --type bool \
      --set /apps/gdm/simple-greeter/banner_message_enable true

To display a banner, this setting must be enabled and then banner text must also be set.

CCI-NaN
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gconf_gdm_set_login_banner_text

medium

Set GUI Warning Banner Text

An appropriate warning message reinforces policy awareness during the login process and facilitates possible legal action against attackers.

To set the text shown by the GNOME Display Manager in the login screen, run the following command:

    $ sudo gconftool-2 --direct \
      --config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory \
      --type string \
      --set /apps/gdm/simple-greeter/banner_message_text \
      "Text of the warning banner here"

When entering a warning banner that spans several lines, remember to begin and end the string with `"`. This command writes directly either to the `/etc/gconf/gconf.xml.mandatory/%gconf-tree.xml` if it exists or to the file `/etc/gconf/gconf.xml.mandatory/apps/gdm/simple-greeter/%gconf.xml`. Either of these files can later be edited directly if necessary.

CCI-NaN
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gconf_gdm_disable_user_list

medium

Disable the User List

Leaving the user list enabled is a security risk since it allows anyone with physical access to the system to quickly enumerate known user accounts without logging in.

In the default graphical environment, users logging directly into the system are greeted with a login screen that displays all known users. This functionality should be disabled.
Run the following command to disable the user list:

    $ sudo gconftool-2 --direct \
      --config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory \
      --type bool \
      --set /apps/gdm/simple-greeter/disable_user_list true

CCI-NaN

service_bluetooth_disabled

medium

Disable Bluetooth Service

Disabling the `bluetooth` service prevents the system from attempting connections to Bluetooth devices, which entails some security risk. Nevertheless, variation in this risk decision may be expected due to the utility of Bluetooth connectivity and its limited range.

The `bluetooth` service can be disabled with the following command:

    $ sudo chkconfig bluetooth off

    $ sudo service bluetooth stop

CCI-NaN
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account_disable_post_pw_expiration

unknown

Set Account Expiration Following Inactivity

Disabling inactive accounts ensures that accounts which may not have been responsibly removed are not available to attackers who may have compromised their credentials.

To specify the number of days after a password expires (which signifies inactivity) until an account is permanently disabled, add or correct the following lines in `/etc/default/useradd`, substituting `NUM_DAYS` appropriately:

    INACTIVE=

A value of 35 is recommended. If a password is currently on the verge of expiration, then 35 days remain until the account is automatically disabled. However, if the password will not expire for another 60 days, then 95 days could elapse until the account would be automatically disabled. See the `useradd` man page for more information. Determining the inactivity timeout must be done with careful consideration of the length of a "normal" period of inactivity for users in the particular environment. Setting the timeout too low incurs support costs and also has the potential to impact availability of the system to legitimate users.

CCI-NaN
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dir_perms_world_writable_sticky_bits

unknown

Verify that All World-Writable Directories Have Sticky Bits Set

Failing to set the sticky bit on public directories allows unauthorized users to delete files in the directory structure.
The only authorized public directories are those temporary directories supplied with the system, or those designed to be temporary file repositories. The setting is normally reserved for directories used by the system, by users for temporary file storage (such as `/tmp`), and for directories requiring global read/write access.

When the so-called 'sticky bit' is set on a directory, only the owner of a given file may remove that file from the directory. Without the sticky bit, any user with write access to a directory may remove any file in the directory. Setting the sticky bit prevents users from removing each other's files. In cases where there is no reason for a directory to be world-writable, a better solution is to remove that permission rather than to set the sticky bit. However, if a directory is used by a particular application, consult that application's documentation instead of blindly changing modes.
To set the sticky bit on a world-writable directory DIR, run the following command:

    $ sudo chmod +t DIR

dir_perms_world_writable_system_owned

unknown

Ensure All World-Writable Directories Are Owned by a System Account

Allowing a user account to own a world-writable directory is undesirable because it allows the owner of that directory to remove or replace any files that may be placed in the directory by other users.

All directories in local partitions which are world-writable should be owned by root or another system account. If any world-writable directories are not owned by a system account, this should be investigated. Following this, the files should be deleted or assigned to an appropriate group.

tftpd_uses_secure_mode

high

Ensure tftp Daemon Uses Secure Mode

Using the `-s` option causes the TFTP service to only serve files from the given directory. Serving files from an intentionally-specified directory reduces the risk of sharing files which should remain private.

If running the `tftp` service is necessary, it should be configured to change its root directory at startup. To do so, ensure `/etc/xinetd.d/tftp` includes `-s` as a command line argument, as shown in the following example (which is also the default):

    server_args = -s /var/lib/tftpboot

CCI-NaN

ftp_log_transactions

unknown

Enable Logging of All FTP Transactions

To trace malicious activity facilitated by the FTP service, it must be configured to ensure that all commands sent to the FTP server are logged using the verbose vsftpd log format. The default vsftpd log file is `/var/log/vsftpd.log`.

Add or correct the following configuration options within the `vsftpd` configuration file, located at `/etc/vsftpd/vsftpd.conf`:

    xferlog_enable=YES
    xferlog_std_format=NO
    log_ftp_protocol=YES

snmpd_use_newer_protocol

medium

Configure SNMP Service to Use Only SNMPv3 or Newer

Earlier versions of SNMP are considered insecure, as they potentially allow unauthorized access to detailed system management information.

Edit `/etc/snmp/snmpd.conf`, removing any references to `rocommunity`, `rwcommunity`, or `com2sec`. Upon doing that, restart the SNMP service:

    $ sudo service snmpd restart

snmpd_not_default_password

high

Ensure Default Password Is Not Used

Presence of the default SNMP password enables querying of different system aspects and could result in unauthorized knowledge of the system.

Edit `/etc/snmp/snmpd.conf`, remove default community string `public`. Upon doing that, restart the SNMP service:

    $ sudo service snmpd restart

accounts_umask_etc_bashrc

unknown

Ensure the Default Bash Umask is Set Correctly

The umask value influences the permissions assigned to files when they are created. A misconfigured umask value could result in files with excessive permissions that can be read or written to by unauthorized users.

To ensure the default umask for users of the Bash shell is set properly, add or correct the `umask` setting in `/etc/bashrc` to read as follows:

    umask

CCI-NaN

accounts_umask_etc_csh_cshrc

unknown

Ensure the Default C Shell Umask is Set Correctly

The umask value influences the permissions assigned to files when they are created. A misconfigured umask value could result in files with excessive permissions that can be read or written to by unauthorized users.

To ensure the default umask for users of the C shell is set properly, add or correct the `umask` setting in `/etc/csh.cshrc` to read as follows:

    umask

CCI-NaN

accounts_umask_etc_profile

unknown

Ensure the Default Umask is Set Correctly in /etc/profile

The umask value influences the permissions assigned to files when they are created. A misconfigured umask value could result in files with excessive permissions that can be read or written to by unauthorized users.

To ensure the default umask controlled by `/etc/profile` is set properly, add or correct the `umask` setting in `/etc/profile` to read as follows:

    umask

CCI-NaN

accounts_umask_etc_login_defs

unknown

Ensure the Default Umask is Set Correctly in login.defs

The umask value influences the permissions assigned to files when they are created. A misconfigured umask value could result in files with excessive permissions that can be read and written to by unauthorized users.

To ensure the default umask controlled by `/etc/login.defs` is set properly, add or correct the `UMASK` setting in `/etc/login.defs` to read as follows:

    UMASK

CCI-NaN

umask_for_daemons

unknown

Set Daemon Umask

The umask influences the permissions assigned to files created by a process at run time. An unnecessarily permissive umask could result in files being created with insecure permissions.

The file `/etc/init.d/functions` includes initialization parameters for most or all daemons started at boot time. The default umask of 022 prevents creation of group- or world-writable files. To set the default umask for daemons, edit the following line, inserting 022 or 027 for umask appropriately:

    umask

Setting the umask to too restrictive a setting can cause serious errors at runtime. Many daemons on the system already individually restrict themselves to a umask of 077 in their own init scripts.

no_netrc_files

medium

Verify No netrc Files Exist

Unencrypted passwords for remote FTP servers may be stored in `.netrc` files. DoD policy requires passwords be encrypted in storage and not used in access scripts.

The `.netrc` files contain login information used to auto-login into FTP servers and reside in the user's home directory. These files may contain unencrypted passwords to remote FTP servers making them susceptible to access by unauthorized users and should not be used. Any `.netrc` files should be removed.

CCI-NaN

ftp_present_banner

medium

Create Warning Banners for All FTP Users

This setting will cause the system greeting banner to be used for FTP connections as well.

Edit the vsftpd configuration file, which resides at `/etc/vsftpd/vsftpd.conf` by default. Add or correct the following configuration options:

    banner_file=/etc/issue

CCI-NaN

smartcard_auth

medium

Enable Smart Card Login

Smart card login provides two-factor authentication stronger than that provided by a username and password combination. Smart cards leverage PKI (public key infrastructure) in order to provide and verify credentials.

To enable smart card authentication, consult the documentation at:

- https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Managing_Smart_Cards/enabling-smart-card-login.html

For guidance on enabling SSH to authenticate against a Common Access Card (CAC), consult documentation at:

- https://access.redhat.com/solutions/82273

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display_login_attempts

unknown

Set Last Login/Access Notification

Users need to be aware of activity that occurs regarding their account. Providing users with information regarding the number of unsuccessful attempts that were made to login to their account allows the user to determine if any unauthorized activity has occurred and gives them an opportunity to notify administrators.

To configure the system to notify users of last login/access using `pam_lastlog`, add the following line immediately after `session required pam_limits.so`:

    session       required     pam_lastlog.so showfailed

CCI-NaN

accounts_passwords_pam_faillock_unlock_time

medium

Set Lockout Time For Failed Password Attempts

Locking out user accounts after a number of incorrect attempts prevents direct password guessing attacks. Ensuring that an administrator is involved in unlocking locked accounts draws appropriate attention to such situations.

To configure the system to lock out accounts after a number of incorrect login attempts and require an administrator to unlock the account using `pam_faillock.so`, modify the content of both `/etc/pam.d/system-auth` and `/etc/pam.d/password-auth` as follows:

- Add the following line immediately `before` the `pam_unix.so` statement in the `AUTH` section:

      auth required pam_faillock.so preauth silent deny= unlock_time= fail_interval=

- Add the following line immediately `after` the `pam_unix.so` statement in the `AUTH` section:

      auth [default=die] pam_faillock.so authfail deny= unlock_time= fail_interval=

- Add the following line immediately `before` the `pam_unix.so` statement in the `ACCOUNT` section:

      account required pam_faillock.so

CCI-NaN

accounts_passwords_pam_faillock_interval

medium

Set Interval For Counting Failed Password Attempts

Locking out user accounts after a number of incorrect attempts within a specific period of time prevents direct password guessing attacks.

Utilizing `pam_faillock.so`, the `fail_interval` directive configures the system to lock out accounts after a number of incorrect login attempts. Modify the content of both `/etc/pam.d/system-auth` and `/etc/pam.d/password-auth` as follows:

- Add the following line immediately `before` the `pam_unix.so` statement in the `AUTH` section:

      auth required pam_faillock.so preauth silent deny= unlock_time= fail_interval=

- Add the following line immediately `after` the `pam_unix.so` statement in the `AUTH` section:

      auth [default=die] pam_faillock.so authfail deny= unlock_time= fail_interval=

- Add the following line immediately `before` the `pam_unix.so` statement in the `ACCOUNT` section:

      account required pam_faillock.so

CCI-NaN

gconf_gnome_disable_ctrlaltdel_reboot

high

Disable Ctrl-Alt-Del Reboot Key Sequence in GNOME

A locally logged-in user who presses Ctrl-Alt-Del, when at the console, can reboot the system. If accidentally pressed, as could happen in the case of mixed OS environment, this can create the risk of short-term loss of availability of systems due to unintentional reboot.

By default, `GNOME` will reboot the system if the `Ctrl-Alt-Del` key sequence is pressed.
To configure the system to ignore the `Ctrl-Alt-Del` key sequence from the Graphical User Interface (GUI) instead of rebooting the system, run the following:

    $ sudo gconftool-2 --direct \
      --config-source xml:readwrite:/etc/gconf/gconf.xml.mandatory \
      --type string \
      --set /apps/gnome_settings_daemon/keybindings/power ""

CCI-NaN

postfix_client_configure_mail_alias

medium

Configure System to Forward All Mail For The Root Account

A number of system services utilize email messages sent to the root user to notify system administrators of active or impending issues. These messages must be forwarded to at least one monitored email address.

Set up an alias for root that forwards to a monitored email address:

    $ sudo echo "root: " >> /etc/aliases
    $ sudo newaliases

CCI-NaN

account_use_centralized_automated_auth

medium

Use Centralized and Automated Authentication

A comprehensive account management process that includes automation helps to ensure the accounts designated as requiring attention are consistently and promptly addressed. Enterprise environments make user account management challenging and complex. A user management process requiring administrators to manually address account management functions adds risk of potential oversight.

Implement an automated system for managing user accounts that minimizes the risk of errors, either intentional or deliberate. This system should integrate with an existing enterprise user management system, such as one based on Identity Management tools such as Active Directory, Kerberos, Directory Server, etc.

CCI-NaN

no_password_auth_for_systemaccounts

medium

Ensure that System Accounts Are Locked

Disabling authentication for default system accounts makes it more difficult for attackers to make use of them to compromise a system.false

Some accounts are not associated with a human user of the system, and exist to perform some administrative function. An attacker should not be able to log into these accounts.
System accounts are those user accounts with a user ID less than UID_MIN, where value of the UID_MIN directive is set in `/etc/login.defs` configuration file. In the default configuration UID_MIN is set to 500, thus system accounts are those user accounts with a user ID less than 500. If any system account SYSACCT (other than root) has an unlocked password, disable it with the command:

    $ sudo passwd -l SYSACCT

CCI-NaN

wireless_disable_interfaces

medium

Deactivate Wireless Network Interfaces

The use of wireless networking can introduce many different attack vectors into the organization's network. Common attack vectors such as malicious association and ad hoc networks will allow an attacker to spoof a wireless access point (AP), allowing validated systems to connect to the malicious AP and enabling the attacker to monitor and record network traffic. These malicious APs can also serve to create a man-in-the-middle attack or be used to create a denial of service to valid network resources.

Deactivating wireless network interfaces should prevent normal usage of the wireless capability.
First, identify the interfaces available with the command:

    $ ifconfig -a

Additionally, the following command may be used to determine whether wireless support is included for a particular interface, though this may not always be a clear indicator:

    $ iwconfig

After identifying any wireless interfaces (which may have names like `wlan0`, `ath0`, `wifi0`, `em1` or `eth0`), deactivate the interface with the command:

    $ sudo ifdown interface

These changes will only last until the next reboot. To disable the interface for future boots, remove the appropriate interface file from `/etc/sysconfig/network-scripts`:

    $ sudo rm /etc/sysconfig/network-scripts/ifcfg-interface

CCI-NaN
CCI-NaN

configure_user_data_backups

medium

Configure Backups of User Data

Operating system backup is a critical step in maintaining data assurance and availability. User-level information is data generated by information system and/or application users. Backups shall be consistent with organizational recovery time and recovery point objectives.false

The operating system must conduct backups of user data contained in the operating system. The operating system provides utilities for automating backups of user data. Commercial and open-source products are also available.

CCI-NaN