SI-19(8)_motivated-intruder

SI-19(8) Motivated Intruder

Enhancement of: SI-19

High-Level Description

Family: System and Information Integrity (SI) Framework: NIST SP 800-53 Rev 5

A motivated intruder test is a test in which an individual or group takes a data release and specified resources and attempts to re-identify one or more individuals in the de-identified dataset. Such tests specify the amount of inside knowledge, computational resources, financial resources, data, and skills that intruders possess to conduct the tests. A motivated intruder test can determine if the de-identification is insufficient. It can also be a useful diagnostic tool to assess if de-identification is likely to be sufficient. However, the test alone cannot prove that de-identification is sufficient.

What to Check

• Verify SI-19(8) Motivated Intruder is documented in SSP
• Confirm control is operating effectively
• Review evidence of continuous monitoring for SI-19(8)
• Verify enhancement builds upon base control SI-19

How to Test

Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for SI-19(8) 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 motivated intruder test on the de-identified dataset to determine if the identified data remains or if the de-identified data can be re-identified.

Implementation Guidance

A motivated intruder test is a test in which an individual or group takes a data release and specified resources and attempts to re-identify one or more individuals in the de-identified dataset. Such tests specify the amount of inside knowledge, computational resources, financial resources, data, and skills that intruders possess to conduct the tests. A motivated intruder test can determine if the de-identification is insufficient. It can also be a useful diagnostic tool to assess if de-identification is likely to be sufficient. However, the test alone cannot prove that de-identification is sufficient.

Risk Assessment

CWE Categories

References

• NIST SP 800-53 Rev 5 - SI-19(8)
• 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 (none) reviewed