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.

Check

Verify AlmaLinux OS 9 is configured to lock an account after three unsuccessful logon attempts with the command:

$ grep deny /etc/security/faillock.conf

deny = 3

If the "deny" option is not set to 3 or less (but not 0), is missing or commented out, this is a finding.

Fix

Configure AlmaLinux OS 9 to lock an account when three unsuccessful logon attempts occur using pam_faillock.

First, enable the feature using the following command:

$ authselect enable-feature with-faillock

Then, add or update the following line in the "/etc/security/faillock.conf" file:

deny = 3