4.4.3.2.5 Ensure password maximum sequential characters is configured

Information

The pwquality maxsequence option sets the maximum length of monotonic character sequences in the new password. Examples of such sequence are 12345 or fedcb The check is disabled if the value is 0

Note: Most such passwords will not pass the simplicity check unless the sequence is only a minor part of the 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 maxsequence to 3 or less and not 0 Ensure setting conforms to local site policy:

Example:

# sed -ri 's/^s*maxsequences*=/# &/' /etc/security/pwquality.conf
# printf '
%s' "maxsequence = 3" >> /etc/security/pwquality.conf.d/50-pwmaxsequence.conf

Run the following script to remove setting maxsequence on the pam_pwquality.so module in the PAM files:

#!/usr/bin/env bash

{
for l_pam_file in system-auth password-auth; do
l_authselect_file="/etc/authselect/$(head -1 /etc/authselect/authselect.conf | grep 'custom/')/$l_pam_file"
sed -ri 's/(^s*passwords+(requisite|required|sufficient)s+pam_pwquality.so.*)(s+maxsequences*=s*S+)(.*$)/14/' "$l_authselect_file"
done
authselect apply-changes
}

See Also

https://workbench.cisecurity.org/benchmarks/15289

Item Details

Category: IDENTIFICATION AND AUTHENTICATION

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

Plugin: Unix

Control ID: ad011541e3de08c3a0a8533f85f334e9c1b4031d6a7d56139a2a8a6c154ba1aa