| name | AC-20(1)_limits-on-authorized-use |
| description | Permit authorized individuals to use an external system to access the system or to process, store, or transmit organization-controlled information onl |
| category | authorization |
| version | 5.2.0 |
| author | cyberstrike-official |
| tags | ["nist","sp800-53","rev5","ac-20-1","ac","enhancement"] |
| tech_stack | ["aws","azure","gcp","linux","windows"] |
| cwe_ids | ["CWE-284"] |
| chains_with | ["CA-2"] |
| prerequisites | ["AC-20"] |
| severity_boost | {"CA-2":"Chain with CA-2 for comprehensive security coverage"} |
AC-20(1) Limits on Authorized Use
Enhancement of: AC-20
High-Level Description
Family: Access Control (AC)
Framework: NIST SP 800-53 Rev 5
Limiting authorized use recognizes circumstances where individuals using external systems may need to access organizational systems. Organizations need assurance that the external systems contain the necessary controls so as not to compromise, damage, or otherwise harm organizational systems. Verification that the required controls have been implemented can be achieved by external, independent assessments, attestations, or other means, depending on the confidence level required by organizations.
What to Check
How to Test
Step 1: Review Documentation
Examine the System Security Plan (SSP) and related artifacts for AC-20(1) 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
Permit authorized individuals to use an external system to access the system or to process, store, or transmit organization-controlled information only after:
Verification of the implementation of controls on the external system as specified in the organization’s security and privacy policies and security and privacy plans; or
Retention of approved system connection or processing agreements with the organizational entity hosting the external system.
