SV-26569r1: The at.allow file must be group-owned by root, bin, sys, or cron. | Red Hat Enterprise Linux 5 Security Technical Implementation Guide

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Assessment Title

Rule Text

The at.allow file must be group-owned by root, bin, sys, or cron.

Description

Discussion Text

If the group owner of the at.allow file is not set to root, bin, sys, or cron, unauthorized users could be allowed to view or edit the list of users permitted to run "at" jobs. Unauthorized modification could result in Denial of Service to authorized "at" users or provide unauthorized users with the ability to run "at" jobs.

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

IA Controls

NIST SP 800-53

Not mappedCCI-000225

Additional Details

Responsibility

System Administrator

IA Controls

ECLP-1

References

DPMS Target Red Hat 5 DISA DPMS Target Red Hat 5 2154

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.fso.rhel11:def:221
# The at.allow file must be group-owned by root, bin, sys, or cron.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# Test group of /etc/at.allow is root
# file_object (file_test)
test_1() {
  [ "$(stat -c '%g' '/etc/at.allow')" -eq 0 ]
}
# Test group of /etc/at.allow is bin
# file_object (file_test)
test_2() {
  [ "$(stat -c '%g' '/etc/at.allow')" = "$(sed -En 's/^bin:[^:]*:([0-9]+):/\1/p' '/etc/group')" ]
}
# Test existence of group bin
# textfilecontent54_object (textfilecontent54_test)
test_3() {
  grep -Pq '^bin:[^:]*:([0-9]+):' '/etc/group' &>/dev/null
}
# Test existence of group sys
# textfilecontent54_object (textfilecontent54_test)
test_4() {
  grep -Pq '^sys:[^:]*:([0-9]+):' '/etc/group' &>/dev/null
}
# Test group of /etc/at.allow is sys
# file_object (file_test)
test_5() {
  [ "$(stat -c '%g' '/etc/at.allow')" = "$(sed -En 's/^sys:[^:]*:([0-9]+):/\1/p' '/etc/group')" ]
}

if ! ( test_1 || ( test_2 && test_3 ) || ( test_4 && test_5 ) ); 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.fso.rhel11:def:221

if [ ! -f "/etc/at.allow" ]; then
  echo "PASS"
  exit 0
fi

if [ "$(stat -c '%G' /etc/at.allow)" = "root" ] || [ "$(stat -c '%G' /etc/at.allow)" = "bin" ] || [ "$(stat -c '%G' /etc/at.allow)" = "sys" ] || [ "$(stat -c '%G' /etc/at.allow)" = "cron" ]; then
  echo "PASS"
  exit 0
else
  echo "FAIL"
  exit 1
fi

Remediation

Change the group ownership of the file.

Procedure:
# chgrp root /etc/at.allow