Cis GCP Cos 5.3.1.1

5.3.1.1 Ensure password expiration is 365 days or less (Automated)

Description

The PASS_MAX_DAYS parameter in /etc/login.defs allows an administrator to force passwords to expire once they reach a defined age. It is recommended that the PASS_MAX_DAYS parameter be set to less than or equal to 365 days.

Rationale

The window of opportunity for an attacker to leverage compromised credentials or successfully compromise credentials via an online brute force attack is limited by the age of the password. Therefore, reducing the maximum age of a password also reduces an attacker's window of opportunity.

Audit Procedure

Run the following command and verify PASS_MAX_DAYS conforms to site policy (no more than 365 days):

# grep PASS_MAX_DAYS /etc/login.defs

PASS_MAX_DAYS 365

Run the following command and Review list of users and PASS_MAX_DAYS to verify that all users' PASS_MAX_DAYS conforms to site policy (no more than 365 days):

# grep -E '^[^:]+:[^!*]' /etc/shadow | cut -d: -f1,5

<user>:<PASS_MAX_DAYS>

Expected Result

PASS_MAX_DAYS should be 365 or less in /etc/login.defs and for all users with a password in /etc/shadow.

Remediation

Set the PASS_MAX_DAYS parameter to conform to site policy in /etc/login.defs:

PASS_MAX_DAYS 365

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

# chage --maxdays 365 <user>

Additional Information:

You can also check this setting in /etc/shadow directly. The 5th field should be 365 or less for all users with a password.

Note: A value of -1 will disable password expiration. Additionally the password expiration must be greater than the minimum days between password changes or users will be unable to change their password.

CIS Controls

Profile

• Level 2 - Server