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The system must require passwords to contain at least one lowercase alphabetic character.


Finding ID Version Rule ID IA Controls Severity
V-38571 RHEL-06-000059 SV-50372r1_rule Low
Requiring a minimum number of lowercase characters makes password guessing attacks more difficult by ensuring a larger search space.
Red Hat Enterprise Linux 6 Security Technical Implementation Guide 2015-05-26


Check Text ( C-46129r1_chk )
To check how many lowercase characters are required in a password, run the following command:

$ grep pam_cracklib /etc/pam.d/system-auth

The "lcredit" parameter (as a negative number) will indicate how many special characters are required. The DoD requires at least one lowercase character in a password. This would appear as "lcredit=-1".
If lcredit is not found or not set to the required value, this is a finding.
Fix Text (F-43519r1_fix)
The pam_cracklib module's "lcredit=" parameter controls requirements for usage of lowercase letters in a password. When set to a negative number, any password will be required to contain that many lowercase characters. When set to a positive number, pam_cracklib will grant +1 additional length credit for each lowercase character. Add "lcredit=-1" after pam_cracklib.so to require use of a lowercase character in passwords.