RHEL 8 must require the maximum number of repeating characters be limited to three when passwords are changed.

STIG ID: RHEL-08-020150  |  SRG: SRG-OS-000072-GPOS-00040 | Severity: medium |  CCI: CCI-000195

Vulnerability Discussion

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.

RHEL 8 utilizes "pwquality" as a mechanism to enforce password complexity. The "maxrepeat" option sets the maximum number of allowed same consecutive characters in a new password.

Check

Check for the value of the "maxrepeat" option with the following command:

$ sudo grep -r maxrepeat /etc/security/pwquality.conf*

/etc/security/pwquality.conf:maxrepeat = 3

If the value of "maxrepeat" is set to more than "3" or is commented out, this is a finding.
If conflicting results are returned, this is a finding.

Fix

Configure the operating system to require the change of the number of repeating consecutive characters when passwords are changed by setting the "maxrepeat" option.

Add the following line to "/etc/security/pwquality.conf conf" (or modify the line to have the required value):

maxrepeat = 3

Remove any configurations that conflict with the above value.