5.3.3.2.1 Ensure password number of changed characters is configured

Information

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

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.

Solution

Create or modify a file ending inconf in the /etc/security/pwquality.conf.d/ directory or the file /etc/security/pwquality.conf and add or modify the following line to set difok to 2 or more. Ensure setting conforms to local site policy:

Example:

#!/usr/bin/env bash

{
sed -ri 's/^s*difoks*=/# &/' /etc/security/pwquality.conf
[ ! -d /etc/security/pwquality.conf.d/ ] && mkdir /etc/security/pwquality.conf.d/
printf '
%s' "difok = 2" > /etc/security/pwquality.conf.d/50-pwdifok.conf
}

Run the following command:

# grep -Pl -- 'bpam_pwquality.soh+([^#
r]+h+)?difokb' /usr/share/pam-configs/*

Edit any returned files and remove the difok argument from the pam_pwquality.so line(s):

See Also

https://workbench.cisecurity.org/benchmarks/18960

Item Details

Category: IDENTIFICATION AND AUTHENTICATION

References: 800-53|IA-5(1), CSCv7|4.4

Plugin: Unix

Control ID: 46da9c8a77457bf80833eeb7d7af051b7d606a4fb91ac119b47998390fd1655e