SV-258233r1015136: RHEL 9 pam_unix.so module must be configured in the password-auth file to use a FIPS 140-3 approved cryptographic hashing algorithm for system authentication. | Red Hat Enterprise Linux 9 STIG SCAP Benchmark

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Assessment Title

Rule Text

RHEL 9 pam_unix.so module must be configured in the password-auth file to use a FIPS 140-3 approved cryptographic hashing algorithm for system authentication.

Description

Discussion Text

Unapproved mechanisms that are used for authentication to the cryptographic module are not verified and; therefore, cannot be relied upon to provide confidentiality or integrity, and DOD data may be compromised. RHEL 9 systems utilizing encryption are required to use FIPS-compliant mechanisms for authenticating to cryptographic modules. FIPS 140-3 is the current standard for validating that mechanisms used to access cryptographic modules utilize authentication that meets DOD requirements. This allows for Security Levels 1, 2, 3, or 4 for use on a general-purpose computing system.

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

IA Controls

NIST SP 800-53

Not mappedCCI-004062Not mappedCCI-000196

References

DPMS Target Red Hat Enterprise Linux 9 DISA DPMS Target Red Hat Enterprise Linux 9 5551

Checks

DISA STIG (Manual Reference)

Verify that the pam_unix.so module is configured to use sha512 in /etc/pam.d/password-auth with the following command:

$ grep "^password.*pam_unix.so.*sha512" /etc/pam.d/password-auth

password sufficient pam_unix.so sha512

If "sha512" is missing, or the line is commented out, this is a finding.

If the system administrator (SA) can demonstrate that the required configuration is contained in a PAM configuration file included or substacked from the system-auth file, this is not 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.rhel9os:def:258233
# RHEL 9 pam_unix.so module must be configured in the password-auth file to use a FIPS 140-3 approved cryptographic hashing algorithm for system authentication.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# /etc/pam.d/password-auth:password includes pam_unix.so sha512
# textfilecontent54_object (textfilecontent54_test)
test_1() {
  grep -Pq '^[ \t]*password[ \t]+sufficient[ \t]+pam_unix\.so(?:[ \t]+|(?:[ \t][^#\r\f\n]+[ \t]))sha512(?:[ \t]|$)' '/etc/pam.d/password-auth' &>/dev/null
}

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
# Implements DISA STIG OVAL definition: oval:mil.disa.stig.rhel9os:def:258233

FILE="/etc/pam.d/password-auth"
if [ ! -f "$FILE" ]; then
  echo "PASS"
  exit 0
fi

if grep -q "^[ \t]*password[ \t]+sufficient[ \t]+pam_unix\\.so[ \t]+sha512[ \t]*$" "$FILE"; then
  echo "PASS"
  exit 0
else
  echo "FAIL"
  exit 1
fi

Remediation

Configure RHEL 9 to use a FIPS 140-3 approved cryptographic hashing algorithm for system authentication.

Edit/modify the following line in the "/etc/pam.d/password-auth" file to include the sha512 option for pam_unix.so:

password sufficient pam_unix.so sha512