SV-274044r1120120: Amazon Linux 2023 SSH daemon must not allow Generic Security Service Application Program Interface (GSSAPI) authentication. | Amazon Linux 2023 STIG SCAP Benchmark

Loading benchmark…

Assessment Title

Rule Text

Amazon Linux 2023 SSH daemon must not allow Generic Security Service Application Program Interface (GSSAPI) authentication.

Description

Discussion Text

GSSAPI authentication is used to provide additional authentication mechanisms to applications. Allowing GSSAPI authentication through SSH exposes the system's GSSAPI to remote hosts, increasing the attack surface of the system.

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

IA Controls

NIST SP 800-53

Not mappedCCI-001813

References

DPMS Target Amazon Linux 2023 DISA DPMS Target Amazon Linux 2023 5700

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.amzlx23os:def:274044
# Amazon Linux 2023 SSH daemon must not allow Generic Security Service Application Program Interface (GSSAPI) authentication.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# sshd_config includes sshd_config.d
# textfilecontent54_object (textfilecontent54_test)
test_1() {
  (sed -En 's/^\s*include\s+(.*)\s*$/\1/p' '/etc/ssh/sshd_config') | grep -qxF '/etc/ssh/sshd_config.d/*.conf'
}
# /etc/ssh/sshd_config.d: GSSAPIAuthentication is set to no
# textfilecontent54_object (textfilecontent54_test)
test_2() {
  (grep -rhP --include='*.conf' '^\s*(?i)GSSAPIAuthentication(?-i)[ \t]+([\w\"]+)[\s]*(?:|(?:#.*))?$' '/etc/ssh/sshd_config.d' | sed -En 's/^\s*(?i)GSSAPIAuthentication(?-i)[ \t]+([\w\"]+)[\s]*(?:|(?:#.*))?$/\1/p') | grep -Pq '^(no|"no")$'
}
# /etc/ssh/sshd_config: GSSAPIAuthentication is set to no
# textfilecontent54_object (textfilecontent54_test)
test_3() {
  (sed -En 's/^\s*(?i)GSSAPIAuthentication(?-i)[ \t]+([\w\"]+)[\s]*(?:|(?:#.*))?$/\1/p' '/etc/ssh/sshd_config') | grep -Pq '^(no|"no")$'
}

if ( ( test_1 && test_2 ) || test_3 ); 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.ind:tst:24452800

if [ ! -d "/etc/ssh/sshd_config.d" ]; then echo "PASS"; exit 0; fi
if [ -n "$(grep -E "^\\s*(?i)GSSAPIAuthentication(?-i)[ \\t]+=[ \\t]+no[ \\t]*(?:|(?:#.*))?$" /etc/ssh/sshd_config.d/*.conf)" ]; then echo "PASS"; exit 0; fi
if [ -f "/etc/ssh/sshd_config" ]; then if [ "$(grep -E "^\\s*(?i)GSSAPIAuthentication(?-i)[ \\t]+=[ \\t]+no[ \\t]*(?:|(?:#.*))?$" /etc/ssh/sshd_config | grep -c "^")" -ge "1" ]; then echo "PASS"; exit 0; fi; fi
echo "FAIL"; exit 1

Remediation

Configure Amazon Linux 2023 so that the SSH daemon does not allow GSSAPI authentication.

Add or uncomment the following line to "/etc/ssh/sshd_config" or to a file in "/etc/ssh/sshd_config.d" and set the value to "no":

GSSAPIAuthentication no

The SSH service must be restarted for changes to take effect:

$ sudo systemctl restart sshd.service