SV-281266r1268226: RHEL 10 must not allow a noncertificate trusted host Secure Shell (SSH) login to the system. | Red Hat Enterprise Linux 10 STIG SCAP Benchmark

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Assessment Title

Rule Text

RHEL 10 must not allow a noncertificate trusted host Secure Shell (SSH) login to the system.

Description

Discussion Text

SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts. OpenSSH uses the first occurrence of a keyword it sees, and drop-in files are read in lexicographical order at the start of the configuration. Red Hat recommends using drop-in files rather than changing base configuration files.

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

IA Controls

NIST SP 800-53

Not mappedCCI-000213

References

DPMS Target Red Hat Enterprise Linux 10 DISA DPMS Target Red Hat Enterprise Linux 10 5733

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.rhel10os:def:281266
# RHEL 10 must not allow a noncertificate trusted host Secure Shell (SSH) login to the system.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# HostbasedAuthentication is set to no in /etc/ssh/sshd_config and /etc/ssh/sshd_config.d/*.conf
# textfilecontent54_object (textfilecontent54_test)
test_1() {
  ( (sed -En 's/^(?i)\s*HostbasedAuthentication\s+(\w+)$/\1/p' '/etc/ssh/sshd_config') | grep -Pq '^(no|"no")$' ) || ( (grep -rhP --include='*.conf' '^(?i)\s*HostbasedAuthentication\s+(\w+)$' '/etc/ssh/sshd_config.d' | sed -En 's/^(?i)\s*HostbasedAuthentication\s+(\w+)$/\1/p') | grep -Pq '^(no|"no")$' )
}

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.rhel10os:def:281266

if [ ! -f "/etc/ssh/sshd_config" ] || grep -qE '^(?i)\\s*HostbasedAuthentication\\s+(no)$' /etc/ssh/sshd_config ; then
    if [ ! -d "/etc/ssh/sshd_config.d" ] || [ ! -f "/etc/ssh/sshd_config.d/01-no-hostbased.conf" ] || ! grep -qE '^(?i)\\s*HostbasedAuthentication\\s+(no)$' /etc/ssh/sshd_config.d/01-no-hostbased.conf ; then
        echo "FAIL"
        exit 1
    fi
fi

echo "PASS"
exit 0

Remediation

Configure RHEL 10 to not allow a noncertificate trusted host SSH login to the system.

In "/etc/ssh/sshd_config.d", create a drop file that will lexicographically precede 50-redhat.conf and add the following line:

HostbasedAuthentication no

Restart the SSH daemon with the following command for the settings to take effect:

$ sudo systemctl restart sshd.service