SC-31_covert-channel-analysis

SC-31 Covert Channel Analysis

High-Level Description

Family: System and Communications Protection (SC) Framework: NIST SP 800-53 Rev 5

Developers are in the best position to identify potential areas within systems that might lead to covert channels. Covert channel analysis is a meaningful activity when there is the potential for unauthorized information flows across security domains, such as in the case of systems that contain export-controlled information and have connections to external networks (i.e., networks that are not controlled by organizations). Covert channel analysis is also useful for multilevel secure systems, multiple security level systems, and cross-domain systems.

What to Check

• Verify SC-31 Covert Channel Analysis is documented in SSP
• Validate all 2 control requirements are implemented
• Confirm control is operating effectively
• Review evidence of continuous monitoring for SC-31

How to Test

Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for SC-31 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

Perform a covert channel analysis to identify those aspects of communications within the system that are potential avenues for covert [organization-defined] channels; and Estimate the maximum bandwidth of those channels.

Implementation Guidance

Developers are in the best position to identify potential areas within systems that might lead to covert channels. Covert channel analysis is a meaningful activity when there is the potential for unauthorized information flows across security domains, such as in the case of systems that contain export-controlled information and have connections to external networks (i.e., networks that are not controlled by organizations). Covert channel analysis is also useful for multilevel secure systems, multiple security level systems, and cross-domain systems.

Risk Assessment

CWE Categories

References

• NIST SP 800-53 Rev 5 - SC-31
• 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 (AC-3, AC-4, SA-8, SI-11) reviewed