5.4.1.3 Ensure password expiration warning days is 7 or more (Scored)

Level 1 - Server
Level 1 - Workstation 

The PASS_WARN_AGE parameter in /etc/login.defs allows an administrator to notify users that their password will expire in a defined number of days. It is recommended that the PASS_WARN_AGE parameter be set to 7 or more days.

Providing an advance warning that a password will be expiring gives users time to think of a secure password. Users caught unaware may choose a simple password or write it down where it may be discovered.

Run the following command and verify PASS_WARN_AGE is 7 or more:

# grep PASS_WARN_AGE /etc/login.defs 
PASS_WARN_AGE 7

Verify all users with a password have their number of days of warning before password expires set to 7 or more:

# egrep ^[^:]+:[^\!*] /etc/shadow | cut -d: -f1
<list of users> 
# chage --list <user> 
Number of days of warning before password expires : 7

Set the PASS_WARN_AGE parameter to 7 in /etc/login.defs:

PASS_WARN_AGE 7

Modify user parameters for all users with a password set to match:

# chage --warndays 7 <user>

You can also check this setting in /etc/shadow directly. The 6th field should be 7 or more for all users with a password.