Information
If an account has an empty password, anyone could log on and run commands with the privileges of that account. Accounts with empty passwords should never be used in operational environments.
Solution
If an account is configured for password authentication but does not have an assigned password, it may be possible to log on to the account without authenticating.
Remove any instances of the 'nullok' option in '/etc/pam.d/system-auth' and '/etc/pam.d/password-auth' to prevent logons with empty passwords.
Note: Manual changes to the listed files may be overwritten by the 'authconfig' program. The 'authconfig' program should not be used to update the configurations listed in this requirement.