AC-4(4)_flow-control-of-encrypted-information

AC-4(4) Flow Control of Encrypted Information

Enhancement of: AC-4

High-Level Description

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

Flow control mechanisms include content checking, security policy filters, and data type identifiers. The term encryption is extended to cover encoded data not recognized by filtering mechanisms.

What to Check

• Verify AC-4(4) Flow Control of Encrypted Information is documented in SSP
• Confirm control is operating effectively
• Review evidence of continuous monitoring for AC-4(4)
• 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(4) 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

Remediation Guide

Control Statement

Prevent encrypted information from bypassing [organization-defined] by [organization-defined].

Implementation Guidance

Flow control mechanisms include content checking, security policy filters, and data type identifiers. The term encryption is extended to cover encoded data not recognized by filtering mechanisms.

Risk Assessment

CWE Categories

References

• NIST SP 800-53 Rev 5 - AC-4(4)
• NIST SP 800-53A Rev 5 (Assessment Procedures)
• NIST SP 800-53 Rev 5 Full Catalog

Checklist

• Control documented in SSP
• Implementation evidence collected
• Operating effectiveness validated
• Continuous monitoring in place
• Related controls (SI-4) reviewed