SV-204414r982198: The Red Hat Enterprise Linux operating system must be configured so that when passwords are changed the number of repeating characters of the same character class must not be more than four characters. | Red Hat Enterprise Linux 7 STIG SCAP Benchmark

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Assessment Title

Rule Text

The Red Hat Enterprise Linux operating system must be configured so that when passwords are changed the number of repeating characters of the same character class must not be more than four characters.

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.

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

IA Controls

NIST SP 800-53

Not mappedCCI-000195SV-86541V-71917

References

DPMS Target Red Hat Enterprise Linux 7 DISA DPMS Target Red Hat Enterprise Linux 7 2899

Checks

DISA STIG (Manual Reference)

The "maxclassrepeat" option sets the maximum number of allowed same consecutive characters in the same class in the new password.

Check for the value of the "maxclassrepeat" option in "/etc/security/pwquality.conf" with the following command:

$ sudo grep maxclassrepeat /etc/security/pwquality.conf 
maxclassrepeat = 4

If the value of "maxclassrepeat" is set to "0", more than "4" or is commented out, this is a finding.

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.rhel7os:def:204414
# The Red Hat Enterprise Linux operating system must be configured so that when passwords are changed the number of repeating characters of the same character class must not be more than four characters.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# textfilecontent54_object (textfilecontent54_test)
test_1() {
  ( ( [ "$(sed -En 's/^\s*maxclassrepeat\s*=\s*(-?\d*)\s*(?:#.*)?$/\1/p' '/etc/security/pwquality.conf')" -le 4 ] ) && ( [ "$(sed -En 's/^\s*maxclassrepeat\s*=\s*(-?\d*)\s*(?:#.*)?$/\1/p' '/etc/security/pwquality.conf')" -gt 0 ] ) ) || ( ( [ "$(grep -rhP --include='*.conf' '^\s*maxclassrepeat\s*=\s*(-?\d*)\s*(?:#.*)?$' '/etc/security/pwquality.conf.d' | sed -En 's/^\s*maxclassrepeat\s*=\s*(-?\d*)\s*(?:#.*)?$/\1/p')" -le 4 ] ) && ( [ "$(grep -rhP --include='*.conf' '^\s*maxclassrepeat\s*=\s*(-?\d*)\s*(?:#.*)?$' '/etc/security/pwquality.conf.d' | sed -En 's/^\s*maxclassrepeat\s*=\s*(-?\d*)\s*(?:#.*)?$/\1/p')" -gt 0 ] ) )
}

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
# DISA STIG RHEL7OS: def:204414 compliance check

if [ ! -f "/etc/security/pwquality.conf" ]; then echo "PASS"; exit 0; fi
if grep -qE "^\\s*maxclassrepeat\\s*=\\s*4\\s*$" /etc/security/pwquality.conf; then echo "PASS"; exit 0; fi
if grep -qE "^\\s*maxclassrepeat\\s*=\\s*[0-9]+\\s*$" /etc/security/pwquality.conf; then echo "FAIL"; exit 1; fi
echo "FAIL"; exit 1

Remediation

Configure the operating system to require the change of the number of repeating characters of the same character class when passwords are changed by setting the "maxclassrepeat" option.

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

maxclassrepeat = 4