SV-281262r1268226: RHEL 10 must be configured so that Secure Shell (SSH) server configuration files' permissions are not modified. | Red Hat Enterprise Linux 10 STIG SCAP Benchmark

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Assessment Title

Rule Text

RHEL 10 must be configured so that Secure Shell (SSH) server configuration files' permissions are not modified.

Description

Discussion Text

Service configuration files enable or disable features of their respective services, which if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files must be owned by the correct group to prevent unauthorized changes. 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:281262
# RHEL 10 must be configured so that Secure Shell (SSH) server configuration files' permissions are not modified.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.
#
# MANUAL REVIEW REQUIRED -- the module(s) below could not be reconstructed
# into working code from curated SCC reference data, and are excluded from
# the automated result:
#   - file_object (file_test) -- The /etc/ssh/sshd_config.d files have mode 0600 or less permissive: no extractor for field "gexec"

# The /etc/ssh/sshd_config file has mode 0600 or less permissive
# file_object (file_test)
test_1() {
  ( (stat -c '%A' '/etc/ssh/sshd_config' | awk '{print (substr($0,7,1)=="x" || substr($0,7,1)=="s")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config' | awk '{print (substr($0,8,1)=="r")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config' | awk '{print (substr($0,4,1)=="x" || substr($0,4,1)=="s")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config' | awk '{print (substr($0,10,1)=="t" || substr($0,10,1)=="T")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config' | awk '{print (substr($0,7,1)=="s" || substr($0,7,1)=="S")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config' | awk '{print (substr($0,4,1)=="s" || substr($0,4,1)=="S")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config' | awk '{print (substr($0,10,1)=="x" || substr($0,10,1)=="t")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config' | awk '{print (substr($0,9,1)=="w")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config' | awk '{print (substr($0,5,1)=="r")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config' | awk '{print (substr($0,6,1)=="w")?"true":"false"}') | grep -qxF 'false' )
}
# The /etc/ssh/sshd_config.d directory and sub-directories has mode 0600 or less permissive
# file_object (file_test)
test_2() {
  ( (stat -c '%A' '/etc/ssh/sshd_config.d' | awk '{print (substr($0,7,1)=="x" || substr($0,7,1)=="s")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config.d' | awk '{print (substr($0,8,1)=="r")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config.d' | awk '{print (substr($0,4,1)=="x" || substr($0,4,1)=="s")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config.d' | awk '{print (substr($0,10,1)=="t" || substr($0,10,1)=="T")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config.d' | awk '{print (substr($0,7,1)=="s" || substr($0,7,1)=="S")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config.d' | awk '{print (substr($0,4,1)=="s" || substr($0,4,1)=="S")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config.d' | awk '{print (substr($0,10,1)=="x" || substr($0,10,1)=="t")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config.d' | awk '{print (substr($0,9,1)=="w")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config.d' | awk '{print (substr($0,5,1)=="r")?"true":"false"}') | grep -qxF 'false' ) && ( (stat -c '%A' '/etc/ssh/sshd_config.d' | awk '{print (substr($0,6,1)=="w")?"true":"false"}') | grep -qxF 'false' )
}

if ( test_1 && test_2 ); then
  echo "PASS (automated portion only -- MANUAL REVIEW still required, see notes above)"
else
  echo "FAIL (or see MANUAL REVIEW note above)"
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:281262
if [ ! -f "/etc/ssh/sshd_config" ]; then echo "PASS"; exit 0; fi
if [ ! -r "$(stat -c "%A" /etc/ssh/sshd_config | grep -o 'o.*' | tr -d'')" ]; then echo "FAIL"; exit 1; fi
if [ ! -f "/etc/ssh/sshd_config.d" ]; then echo "PASS"; exit 0; fi
if [ ! -d "/etc/ssh/sshd_config.d" ]; then echo "PASS"; exit 0; fi
for file in /etc/ssh/sshd_config.d/*; do
    if [ ! -r "$(stat -c "%A" "$file" | grep -o 'o.*' | tr -d'')" ]; then echo "FAIL"; exit 1; fi
done
echo "PASS"
exit 0

Remediation

Configure RHEL 10 so that SSH server configuration files' permissions are not modified.

Run the following commands to restore the correct permissions of OpenSSH server configuration files:

$ sudo rpm --setugids openssh-server
$ sudo rpm --setperms openssh-server