SV-230290r1069302: The RHEL 8 SSH daemon must not allow authentication using known host’s authentication. | Red Hat Enterprise Linux 8 STIG SCAP Benchmark

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Assessment Title

Rule Text

The RHEL 8 SSH daemon must not allow authentication using known host’s authentication.

Description

Discussion Text

Configuring this setting for the SSH daemon provides additional assurance that remote logon via SSH will require a password, even in the event of misconfiguration elsewhere.

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

IA Controls

NIST SP 800-53

Not mappedCCI-000366

References

DPMS Target Red Hat Enterprise Linux 8 DISA DPMS Target Red Hat Enterprise Linux 8 2921

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.rhel8os:def:230290
# The RHEL 8 SSH daemon must not allow authentication using known host’s authentication.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# /etc/ssh/sshd_config:IgnoreUserKnownHosts == yes
# textfilecontent54_object (textfilecontent54_test)
test_1() {
  (sed -En 's/^\s*(?i)IgnoreUserKnownHosts(?-i)[ \t]+([\w\"]+)[\s]*(?:|(?:#.*))?$/\1/p' '/etc/ssh/sshd_config') | grep -Pq '^(yes|"yes")$'
}

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.rhel8os:def:230290

if grep -qE '^\\s*(?i)IgnoreUserKnownHosts(?-i)[ \\t]+=[ \\t]*(\"yes\"|\"yes\")[\\s]*(?:|(?:#.*))?$' /etc/ssh/sshd_config; then
  echo "PASS"
  exit 0
else
  echo "FAIL"
  exit 1
fi

Remediation

Configure the SSH daemon to not allow authentication using known host’s authentication.

Add the following line in "/etc/ssh/sshd_config", or uncomment the line and set the value to "yes":

IgnoreUserKnownHosts yes

The SSH daemon must be restarted for the changes to take effect. To restart the SSH daemon, run the following command:

$ sudo systemctl restart sshd.service