SV-258088r1155643: RHEL 9 must restrict the use of the "su" command. | Red Hat Enterprise Linux 9 STIG SCAP Benchmark

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Assessment Title

Rule Text

RHEL 9 must restrict the use of the "su" command.

Description

Discussion Text

The "su" program allows to run commands with a substitute user and group ID. It is commonly used to run commands as the root user. Limiting access to such commands is considered a good security practice. Satisfies: SRG-OS-000373-GPOS-00156, SRG-OS-000312-GPOS-00123

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

IA Controls

NIST SP 800-53

Not mappedCCI-004895Not mappedCCI-002165Not mappedCCI-002038

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:258088
# RHEL 9 must restrict the use of the "su" command.
# 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() {
  grep -Pq '^\s*auth\s+(?:required|requisite)\s+pam_wheel\.so(?:\s|$)' '/etc/pam.d/su' &>/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
# OVAL Definition: oval:mil.disa.stig.rhel9os:def:258088
if [ ! -f "/etc/pam.d/su" ]; then echo "PASS"; exit 0; fi
content=$(grep -E "^\\s*auth\\s+(?:required|requisite)\\s+pam_wheel\\.so(\\s|$)" /etc/pam.d/su | wc -l)
if [ $content -ge 1 ]; then echo "PASS"; exit 0; else echo "FAIL"; exit 1; fi

Remediation

Configure RHEL 9 to require users to be in the "wheel" group to run "su" command.

In file "/etc/pam.d/su", uncomment the following line:

"#auth    required    pam_wheel.so use_uid"

$ sed '/^[[:space:]]*#[[:space:]]*auth[[:space:]]\+required[[:space:]]\+pam_wheel\.so[[:space:]]\+use_uid$/s/^[[:space:]]*#//' -i /etc/pam.d/su

If necessary, create a "wheel" group and add administrative users to the group.