TOSS must enforce the limit of five consecutive invalid logon attempts by a user 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 the "/etc/security/faillock.conf" file is configured to lock an account after three unsuccessful logon attempts within 15 minutes:

$ sudo grep -e "deny =" -e "fail_interval =" /etc/security/faillock.conf deny = 3 fail_interval = 900

If the "deny" option is set to "0", more than "3", is missing, or is commented out, this is a finding. If the "fail_interval" option is set to less than "900", is missing, or is commented out, this is a finding.

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

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

deny = 3 fail_interval = 900