SV-274151r1120441: Amazon Linux 2023 must restrict the use of the "su" command. | Amazon Linux 2023 STIG SCAP Benchmark

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Assessment Title

Rule Text

Amazon Linux 2023 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.

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

IA Controls

NIST SP 800-53

Not mappedCCI-002165

References

DPMS Target Amazon Linux 2023 DISA DPMS Target Amazon Linux 2023 5700

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.amzlx23os:def:274151
# Amazon Linux 2023 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.amzlx23os:def:274151

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

PATTERN="^\\s*auth\\s+required\\s+pam_wheel\\.so\\s*$"
if grep -q "$PATTERN" "$FILE" && grep -c "$PATTERN" "$FILE" -ge 1; then
  echo "PASS"
  exit 0
fi

echo "FAIL"
exit 1

Remediation

Configure Amazon Linux 2023 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"

$ sudo 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.