ac-4-20-approved-solutions

name	AC-4(20)_approved-solutions
description	Employ [organization-defined] to control the flow of [organization-defined] across security domains.
category	authorization
version	5.2.0
author	cyberstrike-official
tags	["nist","sp800-53","rev5","ac-4-20","ac","enhancement"]
tech_stack	["aws","azure","gcp","linux","windows"]
cwe_ids	["CWE-284"]
chains_with	[]
prerequisites	["AC-4"]
severity_boost	{}

AC-4(20) Approved Solutions

Enhancement of: AC-4

High-Level Description

Family: Access Control (AC) Framework: NIST SP 800-53 Rev 5

Organizations define approved solutions and configurations in cross-domain policies and guidance in accordance with the types of information flows across classification boundaries. The National Security Agency (NSA) National Cross Domain Strategy and Management Office provides a listing of approved cross-domain solutions. Contact [e-mail] for more information.

What to Check

• Verify AC-4(20) Approved Solutions is documented in SSP
• Confirm control is operating effectively
• Review evidence of continuous monitoring for AC-4(20)
• Verify enhancement builds upon base control AC-4

How to Test

Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for AC-4(20) implementation details. Verify the organization has documented how this control is satisfied.

Step 2: Validate Implementation

# For cloud environments, use cloud-audit-mcp tools
# For on-premises, review system configurations directly

# Example: Check if account management policies exist
grep -r "account.management\|access.control" /etc/security/ 2>/dev/null

Step 3: Test Operating Effectiveness

Verify the control is actively functioning, not just documented. Check logs, configurations, and operational evidence.

Tools

Tool	Purpose	Usage
cloud-audit-mcp	Check IAM policies and access controls	cloud_audit_iam_policies
hackbrowser-mcp	Test web application access controls	browser_auth_test

Remediation Guide

Control Statement

Employ [organization-defined] to control the flow of [organization-defined] across security domains.

Implementation Guidance

Organizations define approved solutions and configurations in cross-domain policies and guidance in accordance with the types of information flows across classification boundaries. The National Security Agency (NSA) National Cross Domain Strategy and Management Office provides a listing of approved cross-domain solutions. Contact for more information.