Vulnerability Discussion

By limiting the number of failed logon attempts, the risk of unauthorized system access via user password guessing, otherwise known as brute-force attacks, is reduced. Limits are imposed by locking the account.

In RHEL 8.2 the "/etc/security/faillock.conf" file was incorporated to centralize the configuration of the pam_faillock.so module. Also introduced is a "local_users_only" option that will only track failed user authentication attempts for local users in /etc/passwd and ignore centralized (AD, IdM, LDAP, etc.) users to allow the centralized platform to solely manage user lockout.

From "faillock.conf" man pages: Note that the default directory that "pam_faillock" uses is usually cleared on system boot so the access will be reenabled after system reboot. If that is undesirable a different tally directory must be set with the "dir" option.

Satisfies: SRG-OS-000021-GPOS-00005, SRG-OS-000329-GPOS-00128

Check

Note: If temporary accounts do not exist or are not used this is not applicable. This check applies to RHEL versions 8.2 or newer, if the system is RHEL version 8.0 or 8.1, this check is not applicable.

Verify the "/etc/security/faillock.conf" file is configured to lock an account until released by an administrator after three unsuccessful logon attempts:

$ sudo grep 'unlock_time =' /etc/security/faillock.conf

unlock_time = 0

If the "unlock_time" option is not set to "0", is missing or commented out, this is a finding.

Fix

Configure the operating system to lock an account until released by an administrator when three unsuccessful logon attempts occur in 15 minutes.

Add/Modify the "/etc/security/faillock.conf" file to match the following line:

unlock_time = 0