AlmaLinux OS 9 must automatically lock an account when three unsuccessful logon attempts occur during a 15-minute time period.

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.

Verify AlmaLinux OS 9 locks an account after three unsuccessful logon attempts within a period of 15 minutes with the following command:

$ grep fail_interval /etc/security/faillock.conf

fail_interval = 900

If the "fail_interval" option is not set to 900 or less (but not 0), the line is commented out, or the line is missing, this is a finding.

Configure AlmaLinux OS 9 to lock an account after a number of incorrect login attempts within 15 minutes using pam_faillock.

First, enable the feature using the following command:

$ authselect enable-feature with-faillock

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

fail_interval = 900