cis-ubuntu1204-v110-9-2-3

name	cis-ubuntu1204-v110-9-2-3
description	Limit Password Reuse
category	cis-os-hardening
version	1.1.0
author	cyberstrike-official
tags	["cis","ubuntu",12.04,"linux","authentication","pam","password-policy"]
cis_id	9.2.3
cis_benchmark	CIS Ubuntu 12.04 LTS Server Benchmark v1.1.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

9.2.3 Limit Password Reuse (Scored)

Profile Applicability

• Level 1

Description

The /etc/security/opasswd file stores the users' old passwords and can be checked to ensure that users are not recycling recent passwords.

Rationale

Forcing users not to reuse their past 5 passwords make it less likely that an attacker will be able to guess the password.

Note that these change only apply to accounts configured on the local system.

Audit Procedure

Using Command Line

Perform the following to determine the current setting for reuse of older passwords:

grep "remember" /etc/pam.d/common-password

Expected Result

password [success=1 default=ignore] pam_unix.so obscure sha512 remember=5

Remediation

Using Command Line

Set the pam_unix.so remember parameter to 5 in /etc/pam.d/common-password:

password sufficient pam_unix.so remember=5

Note: The default password setting in this document is the last 5 passwords. Change this number to conform to your site's password policy.

Default Value

No password reuse limitation is configured by default.

References

• CIS Ubuntu 12.04 LTS Server Benchmark v1.1.0

Profile

Level 1 - Scored