cis-ubuntu1804-v220-4-5-1-6

name	cis-ubuntu1804-v220-4-5-1-6
description	Ensure the number of changed characters in a new password is configured
category	cis-iam
version	2.2.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-18.04","users","password-policy"]
cis_id	4.5.1.6
cis_benchmark	CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0 - Control 4.5.1.6

Profile Applicability

• Level 1 - Server
• Level 1 - Workstation

Description

The pwquality difok option sets the number of characters in a password that must not be present in the old password.

Rationale

Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks.

Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised.

Audit Procedure

Command Line

Run the following command to verify that the difok option in /etc/security/pwquality.conf is set to 2 or more:

grep -Pi '^\h*difok\h*=\h*([2-9]|[1-9][0-9]+)\b' /etc/security/pwquality.conf

Expected Result

difok = 2

Or higher.

Remediation

Command Line

Edit or add the following line in /etc/security/pwquality.conf to a value of 2 or more:

difok = 2

Default Value

difok = 1

References

1. NIST SP 800-53 Rev. 5: IA-5

CIS Controls

v8 - 5.2 Use Unique Passwords - Use unique passwords for all enterprise assets.

v7 - 4.4 Use Unique Passwords.

Profile Applicability

• Level 1 - Server
• Level 1 - Workstation

Assessment Status

Automated