Information
The pam_pwquality.so module checks the strength of passwords. It performs checks such as making sure a password is not a dictionary word, it is a certain length, contains a mix of characters (e.g. alphabet, numeric, other) and more. The following are definitions of the pam_pwquality .so options.
try_first_pass - retrieve the password from a previous stacked PAM module. If not available, then prompt the user for a password.
retry=3 - Allow 3 tries before sending back a failure.
The following options are set in the /etc/security/pwquality.conf file:
minlen = 14 - password must be 14 characters or more
dcredit = -1 - provide at least one digit
ucredit = -1 - provide at least one uppercase character
ocredit = -1 - provide at least one special character
lcredit = -1 - provide at least one lowercase character
The settings shown above are one possible policy. Alter these values to conform to your own organization's password policies.
Rationale:
Strong passwords protect systems from being hacked through brute force methods.
Solution
Edit the /etc/pam.d/password-auth and /etc/pam.d/system-auth files to include the appropriate options for pam_pwquality.so and to conform to site policy:
password requisite pam_pwquality.so try_first_pass retry=3
Edit /etc/security/pwquality.conf to add or update the following settings to conform to site policy:
minlen = 14
dcredit = -1
ucredit = -1
ocredit = -1
lcredit = -1
Notes:
Consult your documentation for the appropriate PAM file and module.
Additional module options may be set, recommendation requirements only cover including try_first_pass and minlen set to 14 or more.
Settings in /etc/security/pwquality.conf must use spaces around the = symbol.
This Benchmark recommendation maps to:
Red Hat Enterprise Linux 7 Security Technical Implementation Guide:
Version 2, Release: 3 Benchmark Date: 26 Apr 2019
Vul ID: V-71903
Rule ID: SV-86527r3_rule
STIG ID: RHEL-07-010120
Severity: CAT II
Vul ID: V-71905
Rule ID: SV-86529r5_rule
STIG ID: RHEL-07-010130
Severity: CAT II
Vul ID: V-71907
Rule ID: SV-86531r3_rule
STIG ID: RHEL-07-010140
Severity: CAT II
Vul ID: V-71909
Rule ID: SV-86533r2_rule
STIG ID: RHEL-07-010150
Severity: CAT II
Vul ID: V-73159
Rule ID: SV-87811r4_rule
STIG ID: RHEL-07-010119
Severity: CAT II