NIST SP 800-53 Rev. 5 SI-20 — Tainting

What this control requires

Embed data or capabilities within systems to detect if organizational data has been exfiltrated or improperly removed. Techniques may include passive or active tainting, such as embedding false data or software that alerts when data is accessed or exfiltrated. This control supports the Data Protection, Incident Response capability within the System and Information Integrity family.

In plain English

Embed data or capabilities within systems to detect if organizational data has been exfiltrated or improperly removed. In practice, this means you can prove you information management-level controls on a defined cadence.

Why it matters

SP 800-53 is the catalogue every U.S. federal authorisation (FedRAMP, FISMA, CMMC) and most regulated industries point at. A missing control surfaces as a Plan of Action & Milestones (POA&M) item that an Authorizing Official must approve before the Authority To Operate is granted or renewed.

This control is rated high. Auditors expect a named owner, a remediation SLA, and a tooling artefact that evidences continuous operation.

What an auditor looks for

A 3PAO (FedRAMP) or Independent Assessor (NIST RMF) tests against NIST SP 800-53A assessment procedures. For each control they expect a documented implementation that addresses every assessment objective (Examine, Interview, Test) and an implementation summary in the System Security Plan.

Within System and Information Integrity, the assessor will trace your implementation back to the catalogue reference (Control SI-20) and look for objective evidence on the latest two assessment cycles.

How to implement

Incident Response

Runbook. Maintain a runbook keyed by incident type with named roles (IC, comms, scribe), an out-of-band comms channel, and a 72-hour timeline for external notification.

Tabletop. Run a quarterly tabletop exercise (ransomware, insider, supply-chain) and feed gaps back into the runbook.

Operational checklist

• Information. Document the trigger, the owner and the cadence.
• Data. Document the trigger, the owner and the cadence.
• Protection. Document the trigger, the owner and the cadence.
• Response. Document the trigger, the owner and the cadence.
• System. Document the trigger, the owner and the cadence.
• Scope: management, information, system, alerts, protection, software, capability, incident response capability.

Evidence to collect

• Ticketing Workflow. ticketing_workflow evidence

Workflow metrics (ServiceNow, Jira) show approvals and remediation. Focus: Tainting.

Common pitfalls

• Runbooks that name a role but no person, or list a paging channel that no longer exists.

How it maps to other frameworks

Computed from shared tags, control component and key-operation subjects — handy when you are reconciling controls across an audit.

• NIST SP 800-171 Rev. 3 3.14.1 — Flaw Remediation
• SOC 2 (2017 TSC) CC7.4 — Incident Response
• CIS Controls v8 17.8 — Conduct Post-Incident Reviews
• ISO/IEC 27001:2022 A.5.27 — Learning from information security incidents

Related controls in NIST SP 800-53 Rev. 5

• Control SI-4(7) — Automated Response To Suspicious Events
• Control SI-4(24) — Indicators Of Compromise
• Control IR-4(11) — Integrated Incident Response Team
• Control IR-7(2) — Coordination With External Providers
• Control SI-7(7) — Integration Of Detection And Response
• Control SC-47 — Alternate Communications Paths

References

• NIST Computer Security Resource Center — NIST SP 800-53 Rev. 5
• Catalogue identifier: Control SI-20

Topics: incident responsechange management