5.3.2.2.2 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:

difok = 2

Example:

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

- OR - If the pam-config tool has been used to configure the global PAM configuration files:

Run the following command to add the difok option to 2 or more and follows local site policy

# pam-config -a --cracklib-difok=2

Note:

- The difok option maybe set to 2 or more and depending on local site policy.
- Best practice for updating pam modules is to configure settings in aconf file in the /etc/security/pwquality.conf.d/ directory or /etc/security/pwquality.conf

See Also

https://workbench.cisecurity.org/benchmarks/20333

Item Details

Category: IDENTIFICATION AND AUTHENTICATION

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

Plugin: Unix

Control ID: d561818d3e4accda4ccadd13028efb95ca0038bb7d8a86eec430fee7fade440b