cis-gcp-cos-5-3-1-2

name	cis-gcp-cos-5.3.1.2
description	Ensure minimum days between password changes is 7 or more
category	cis-gcp-cos
version	1.2.0
author	cyberstrike-official
tags	["cis","gcp","container-optimized-os","shadow","password-expiration","user-accounts"]
cis_id	5.3.1.2
cis_benchmark	CIS Google Container-Optimized OS Benchmark v1.2.0
tech_stack	["gcp","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

5.3.1.2 Ensure minimum days between password changes is 7 or more (Automated)

Description

The PASS_MIN_DAYS parameter in /etc/login.defs allows an administrator to prevent users from changing their password until a minimum number of days have passed since the last time the user changed their password. It is recommended that PASS_MIN_DAYS parameter be set to 7 or more days.

Rationale

By restricting the frequency of password changes, an administrator can prevent users from repeatedly changing their password in an attempt to circumvent password reuse controls.

Audit Procedure

Run the following command and verify PASS_MIN_DAYS conforms to site policy (no less than 7 days):

# grep PASS_MIN_DAYS /etc/login.defs

PASS_MIN_DAYS 7

Run the following command and Review list of users and PASS_MIN_DAYS to Verify that all users' PASS_MIN_DAYS conforms to site policy (no less than 7 days):

# grep -E '^[^:]+:[^\!*]' /etc/shadow | cut -d: -f1,4

<user>:<PASS_MIN_DAYS>

Expected Result

PASS_MIN_DAYS should be 7 or more in /etc/login.defs and for all users with a password in /etc/shadow.

Remediation

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

PASS_MIN_DAYS 7

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

# chage --mindays 7 <user>

Additional Information:

You can also check this setting in /etc/shadow directly. The 4th field should be 7 or more for all users with a password.

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	5.2 Use Unique Passwords - Use unique passwords for all enterprise assets. Best practice implementation includes, at a minimum, an 8-character password for accounts using MFA and a 14-character password for accounts not using MFA.	x	x	x
v7	4.4 Use Unique Passwords - Where multi-factor authentication is not supported (such as local administrator, root, or service accounts), accounts will use passwords that are unique to that system.