cis-ubuntu1604-v200-5-5-1-1

name	cis-ubuntu1604-v200-5-5-1-1
description	Ensure minimum days between password changes is configured
category	cis-iam
version	2.0.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-16.04","authentication","pam"]
cis_id	5.5.1.1
cis_benchmark	CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

Ensure minimum days between password changes is configured

Profile Applicability:

• Level 1 - Server
• Level 1 - Workstation

Assessment Status: 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 1 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

Command Line

Run the following command and verify PASS_MIN_DAYS conforms to site policy (no less than 1 day):

grep PASS_MIN_DAYS /etc/login.defs

Expected output:

PASS_MIN_DAYS 1

Run the following command and Review list of users and PAS_MIN_DAYS to Verify that all users' PAS_MIN_DAYS conforms to site policy (no less than 1 day):

awk -F : '(/^[^:]+:[^!*]/ && $4 < 1){print $1 " " $4}' /etc/shadow

Expected Result:

No <user>:<PASS_MIN_DAYS> should be returned.

Remediation

Command Line

Set the PASS_MIN_DAYS parameter to 1 in /etc/login.defs:

PASS_MIN_DAYS 1

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

chage --mindays 1 <user>

Default Value

PASS_MIN_DAYS 0

References

None

CIS Controls

Controls Version	Control
v6	16 Account Monitoring and Control - Account Monitoring and Control
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.

Profile