Vulnerability Discussion

Limiting the number of logon attempts over a certain time interval reduces the chances that an unauthorized user may gain access to an account.

Check

Verify the Ubuntu operating system enforces a delay of at least 4 seconds between logon prompts following a failed logon attempt with the following command:

$ grep pam_faildelay /etc/pam.d/common-auth

auth required pam_faildelay.so delay=4000000

If the line is not present or is commented out, this is a finding.

Fix

Configure the Ubuntu operating system to enforce a delay of at least 4 seconds between logon prompts following a failed logon attempt.

Edit the file "/etc/pam.d/common-auth" and set the parameter "pam_faildelay" to a value of 4000000 or greater:

auth required pam_faildelay.so delay=4000000