Ubuntu 24.04 LTS must require the change of at least eight characters when passwords are changed.

Severity
Group ID
Group Title
Version
Rule ID
Date
STIG Version
mediumV-270729SRG-OS-000072-GPOS-00040UBTU-24-400290SV-270729r1066676_rule2025-02-181
Description
If Ubuntu 24.04 LTS allows the user to consecutively reuse extensive portions of passwords, this increases the chances of password compromise by increasing the window of opportunity for attempts at guessing and brute-force attacks. The number of changed characters refers to the number of changes required with respect to the total number of positions in the current password. In other words, characters may be the same within the two passwords; however, the positions of the like characters must be different. If the password length is an odd number, then number of changed characters must be rounded up. For example, a password length of 15 characters must require the change of at least eight characters. Satisfies: SRG-OS-000072-GPOS-00040, SRG-OS-000730-GPOS-00190
ℹ️ Check
Verify Ubuntu 24.04 LTS requires the change of at least eight characters when passwords are changed with the following command: $ grep -i "difok" /etc/security/pwquality.conf difok=8 If the "difok" parameter is less than "8" or is commented out, this is a finding.
✔️ Fix
Configure Ubuntu 24.04 LTS to require the change of at least eight characters when passwords are changed. Add or update the "/etc/security/pwquality.conf" file to include the "difok=8" parameter: difok=8