SV-257986r1045030: RHEL 9 must enable the Pluggable Authentication Module (PAM) interface for SSHD. | Red Hat Enterprise Linux 9 STIG SCAP Benchmark

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Assessment Title

Rule Text

RHEL 9 must enable the Pluggable Authentication Module (PAM) interface for SSHD.

Description

Discussion Text

When UsePAM is set to "yes", PAM runs through account and session types properly. This is important when restricted access to services based off of IP, time, or other factors of the account is needed. Additionally, this ensures users can inherit certain environment variables on login or disallow access to the server.

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

IA Controls

NIST SP 800-53

Not mappedCCI-000877

References

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

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:257986
# RHEL 9 must enable the Pluggable Authentication Module (PAM) interface for SSHD.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# /etc/ssh/sshd_config or /etc/ssh/sshd_config.d/*:UsePAM == yes
# textfilecontent54_object (textfilecontent54_test)
test_1() {
  ( (sed -En 's/^\s*UsePAM\s+(\w*)/\1/p' '/etc/ssh/sshd_config') | grep -qxF 'yes' ) || ( (grep -rhP --include='*.conf' '^\s*UsePAM\s+(\w*)' '/etc/ssh/sshd_config.d' | sed -En 's/^\s*UsePAM\s+(\w*)/\1/p') | grep -qxF 'yes' )
}

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.rhel9os:def:257986

if grep -qE '^\\s*UsePAM\\s+yes' /etc/ssh/sshd_config || grep -qE '^\\s*UsePAM\\s+yes' /etc/ssh/sshd_config.d/*.conf; then
  echo "PASS"
  exit 0
else
  echo "FAIL"
  exit 1
fi

Remediation

Configure the RHEL 9 SSHD to use the UsePAM interface by adding or modifying the following line in "/etc/ssh/sshd_config" or in a file in "/etc/ssh/sshd_config.d".

UsePAM yes

Restart the SSH daemon for the settings to take effect:

$ sudo systemctl restart sshd.service