Rule ID
SV-258817r933512_rule
Version
V1R1
CCIs
CCI-000195
If the operating system 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.
At the command line, run the following command to verify at least eight different characters be used: # grep '^password.*pam_pwquality.so' /etc/pam.d/system-password Example result: password requisite pam_pwquality.so dcredit=-1 ucredit=-1 lcredit=-1 ocredit=-1 minlen=15 difok=8 enforce_for_root dictcheck=1 If the "difok" option is not >= 8, is missing or commented out, this is a finding.
Navigate to and open: /etc/pam.d/system-password Configure the pam_pwquality.so line to have the "difok" option set to "8" as follows: password requisite pam_pwquality.so dcredit=-1 ucredit=-1 lcredit=-1 ocredit=-1 minlen=15 difok=8 enforce_for_root dictcheck=1 Note: On vCenter appliances, the equivalent file must be edited under "/etc/applmgmt/appliance", if one exists, for the changes to persist after a reboot.