SV-37475r3: The alias file must have mode 0644 or less permissive. | Red Hat Enterprise Linux 5 Security Technical Implementation Guide

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Assessment Title

Rule Text

The alias file must have mode 0644 or less permissive.

Description

Discussion Text

Excessive permissions on the aliases file may permit unauthorized modification. If the alias file is modified by an unauthorized user, they may modify the file to run malicious code or redirect e-mail.

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

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:284
# The alias file must have mode 0644 or less permissive.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# Test mode of /etc/aliases is 644 or less permissive
# file_object (file_test)
test_1() {
  ( (stat -c '%A' '/etc/aliases' | awk '{print (substr($0,7,1)=="x" || substr($0,7,1)=="s")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/aliases' | awk '{print (substr($0,4,1)=="x" || substr($0,4,1)=="s")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/aliases' | awk '{print (substr($0,7,1)=="s" || substr($0,7,1)=="S")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/aliases' | awk '{print (substr($0,4,1)=="s" || substr($0,4,1)=="S")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/aliases' | awk '{print (substr($0,10,1)=="x" || substr($0,10,1)=="t")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/aliases' | awk '{print (substr($0,9,1)=="w")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/aliases' | awk '{print (substr($0,6,1)=="w")?"true":"false"}') | grep -qxF 'false' )
}

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.fso.rhel11:def:284
if [ ! -f "/etc/aliases" ]; then echo "PASS"; exit 0; fi; if [ ! -r "/etc/aliases" ]; then echo "FAIL"; exit 1; fi; if [ -w "/etc/aliases" ] || [ -x "/etc/aliases" ]; then echo "FAIL"; exit 1; fi; if [ ! -f "/etc/aliases.db" ]; then echo "PASS"; exit 0; fi; if [ ! -r "/etc/aliases.db" ]; then echo "FAIL"; exit 1; fi; if [ -w "/etc/aliases.db" ] || [ -x "/etc/aliases.db" ]; then echo "FAIL"; exit 1; fi; echo "PASS"; exit 0

Remediation

Change the mode of the alias files as needed to function.

No higher than 0644.

Procedure:
for sendmail:
# chmod 0644 /etc/aliases /etc/aliases.db

for postfix (assuming the default postfix directory):
# chmod 0644 /etc/postfix/aliases /etc/postfix/aliases.db