SV-230363r1017175: RHEL 8 must require the change of at least 8 characters when passwords are changed. | Red Hat Enterprise Linux 8 STIG SCAP Benchmark

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Assessment Title

Rule Text

RHEL 8 must require the change of at least 8 characters when passwords are changed.

Description

Discussion Text

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 "difok" option sets the number of characters in a password that must not be present in the old password.

How this relates to the STIG checklist: STIG vs SCAP benchmark.

IA Controls

NIST SP 800-53

Not mappedCCI-000195Not mappedCCI-004066

References

DPMS Target Red Hat Enterprise Linux 8 DISA DPMS Target Red Hat Enterprise Linux 8 2921

SCC Automation Reference

The reconstructed evaluation script behind this rule's OVAL check(s) — every module a compound check combines, with this rule's own concrete values and DISA's SCC tool's real per-module mechanism curated from static teardown of SCC releases.

#!/bin/bash
# Reconstructed from oval:mil.disa.stig.rhel8os:def:230363
# RHEL 8 must require the change of at least 8 characters when passwords are changed.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# at least 8 characters must change when passwords are changed
# textfilecontent54_object (textfilecontent54_test)
test_1() {
  ( [ "$(sed -En 's/^\s*difok\s*=\s*(-?\d*)\s*(?:#.*)?$/\1/p' '/etc/security/pwquality.conf')" -ge 8 ] ) || ( [ "$(grep -rhP --include='*.conf' '^\s*difok\s*=\s*(-?\d*)\s*(?:#.*)?$' '/etc/security/pwquality.conf.d' | sed -En 's/^\s*difok\s*=\s*(-?\d*)\s*(?:#.*)?$/\1/p')" -ge 8 ] )
}

if test_1; then
  echo "PASS"
else
  echo "FAIL"
fi

Assessment Script Powered by AISandbox-executed

A standalone Shell script to assess this control automatically. Review before running it in your environment.

Syntax-checked and actually executed in an isolated sandbox (not the real system this checks) — confirmed to run without errors.

#!/bin/sh
# OVAL Definition: oval:mil.disa.stig.rhel8os:def:230363
if grep -qE '^\\s*difok\\s*=\\s*(8|\\d+)\\s*$' /etc/security/pwquality.conf; then
    echo "PASS"
    exit 0
else
    echo "FAIL"
    exit 1
fi

Remediation

Configure the operating system to require the change of at least eight of the total number of characters when passwords are changed by setting the "difok" option.

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

difok = 8

Remove any configurations that conflict with the above value.