SV-37511r1: The SMTP service must not have the Verify (VRFY) feature active. | Red Hat Enterprise Linux 5 Security Technical Implementation Guide

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Assessment Title

Rule Text

The SMTP service must not have the Verify (VRFY) feature active.

Description

Discussion Text

The VRFY command allows an attacker to determine if an account exists on a system, providing significant assistance to a brute force attack on user accounts. VRFY may provide additional information about users on the system, such as the full names of account owners.

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

IA Controls

NIST SP 800-53

Not mappedCCI-000366

Additional Details

Responsibility

System Administrator

IA Controls

ECSC-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:297
# The SMTP service must not have the Verify (VRFY) feature active.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# vrfy disabled
# textfilecontent54_object (textfilecontent54_test)
test_1() {
  (sed -En 's/^O PrivacyOptions=([^ 	
]*)/\1/p' '/etc/mail/sendmail.cf') | grep -Pq '(^|,)(novrfy|goaway)(,|$)'
}
# sendmail not installed
# rpminfo_object (rpminfo_test)
test_2() {
  ! ( rpm -q --quiet 'sendmail' &>/dev/null )
}

if ( test_1 || test_2 ); 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:297

if ! command -v rpm &> /dev/null; then
  echo "PASS"
  exit 0
fi

sendmail_installed=$(rpm -q --queryformat "%{NAME}\n" sendmail &>/dev/null && echo "yes" || echo "no")
if [ "x$sendmail_installed" = "xno" ]; then
  echo "PASS"
  exit 0
fi

sendmail_cf_path="/etc/mail/sendmail.cf"
if [ ! -f "$sendmail_cf_path" ]; then
  echo "PASS"
  exit 0
fi

grep -qE "(^|,)(novrfy|goaway)(,|$)" "$sendmail_cf_path" || {
  echo "FAIL"
  exit 1
}

echo "PASS"
exit 0

Remediation

Add the "novrfy" flag to your sendmail in /etc/mail/sendmail.cf. 

Procedure:
Edit the definition of "confPRIVACY_FLAGS" in /etc/mail/sendmail.mc to include "novrfy".

Rebuild the sendmail.cf file with:
# make -C /etc/mail

Restart the sendmail service.
# service sendmail restart