SR-3(2): Limitation of Harm

SR-3(2): Limitation of Harm requires you to put specific, documented controls in place to reduce the damage if an adversary can identify and target your supply chain. Operationalize it by selecting “harm-limiting” supply chain controls, assigning owners, building repeatable procedures, and retaining assessment-ready evidence that those procedures run in production. ¹

Key takeaways:

• Treat SR-3(2) as an execution requirement: pick controls, run them continuously, and prove it with artifacts. ¹
• Focus on reducing what an attacker can learn and abuse about your suppliers, dependencies, and weak points.
• Your biggest audit risk is “we do this informally” without mapped ownership, procedures, and recurring evidence. ¹

SR-3(2): limitation of harm requirement sits in the Supply Chain Risk Management (SR) family of NIST SP 800-53 Rev. 5 and targets a practical problem: adversaries don’t need to breach you directly if they can identify, influence, or compromise your supply chain. The control enhancement pushes you to use specific controls that reduce harm even when an attacker can map your ecosystem, target your weakest third party, or exploit a dependency in software, hardware, or services.

For a Compliance Officer, CCO, or GRC lead, SR-3(2) is less about writing a supply chain policy and more about making your supply chain harder to target. That means narrowing supply chain visibility, tightening dependency trust boundaries, and building operational gates so a supplier event does not cascade into organizational impact.

You should approach this requirement the same way an assessor will: “Which controls did you implement to limit harm, who owns them, how do they run, and what evidence shows they ran?” The fastest path is to map SR-3(2) to concrete control owners, implementation procedures, and recurring evidence artifacts. ¹

Regulatory text

Excerpt (verbatim): “Employ the following controls to limit harm from potential adversaries identifying and targeting the organizational supply chain: {{ insert: param, sr-03.02_odp }}.” ¹

Operator interpretation: NIST is telling you to choose and implement a defined set of harm-limiting safeguards (the “organization-defined parameter” list) that reduce the impact of a supply chain attack. Because your organization must define the specific controls in scope, exam readiness hinges on whether you:

1. defined the control set,
2. implemented it consistently across the relevant environment, and
3. can produce evidence that it operates as designed. ¹

Plain-English interpretation (what SR-3(2) is asking for)

Implement safeguards that make it harder for adversaries to successfully target your supply chain and that limit blast radius if they do. In practice, this becomes a set of design and operational decisions that:

• Reduce what an attacker can learn about your suppliers and dependencies (less targeting intelligence).
• Reduce how much trust you place in any single third party or component (less compromise value).
• Reduce propagation pathways from supplier compromise to your environment (smaller blast radius).
• Increase detection speed and response coordination with third parties (less dwell time and impact).

Who it applies to

Entity scope

SR-3(2) commonly applies to:

• Federal information systems and programs implementing NIST SP 800-53 controls. ²
• Contractor systems handling federal data, where NIST SP 800-53 is contractual, inherited through authorization boundaries, or used as the control baseline. ²

Operational context (where auditors expect implementation)

Expect scrutiny where supply chain compromise would create material harm:

• SaaS and cloud service providers with layered third parties (cloud platforms, CI/CD tooling, observability, support).
• Environments that deploy third-party code, containers, agents, or firmware.
• Systems with privileged vendor access (managed service providers, outsourced IT, OEM support).
• Critical suppliers tied to availability, safety, regulated data, or mission operations.

What you actually need to do (step-by-step)

Step 1: Define the “harm-limiting controls” set for your organization

SR-3(2) references an organization-defined list (“{{ insert: param, sr-03.02_odp }}”). Your first deliverable is a written SR-3(2) control set that matches your environment.

Practical approach:

• Start with your existing third-party risk, SDLC, security architecture, and incident response controls.
• Select a short list of controls that demonstrably reduce blast radius and targeting value, such as:
  • Supplier access restrictions and isolation patterns (segmentation, least privilege, just-in-time access).
  • Dependency integrity measures for software and build pipelines (signing, controlled repositories, protected builds).
  • Third-party monitoring and response coordination requirements (security notifications, escalation paths).
  • Alternate supplier/contingency measures for critical dependencies (continuity options where feasible).
• Document inclusion criteria: criticality, data sensitivity, and privilege level.

Control owner action: Assign one accountable owner per control domain (TPRM, Security Engineering, IAM, Procurement, SDLC/DevOps, IR).

Step 2: Map SR-3(2) to owners, procedures, and recurring evidence

Make the requirement assessable. Build a mapping that answers: “Who does what, how often, and what proof exists?”

Minimum mapping fields you should maintain:

• Requirement: sr-3(2): limitation of harm requirement
• Control statement (your organization-defined control)
• Owner and backup owner
• Systems/business units in scope
• Procedure runbook (how it is executed)
• Tooling (ticketing, CI/CD, IAM platform, vendor management system)
• Evidence artifacts produced and retention location

This mapping is explicitly called out as recommended control guidance: map SR-3(2) to control owner, implementation procedure, and recurring evidence artifacts. ¹

Daydream fit (earned): If you struggle to keep mapping and evidence consistent across many third parties and systems, Daydream’s control-to-evidence workflows can help you assign ownership, standardize procedures, and collect artifacts on a recurring cadence without rebuilding your GRC tooling.

Step 3: Implement harm-limiting gates in third-party intake and change management

You need operational “choke points” where SR-3(2) controls trigger automatically:

• New third party onboarding: require security review before procurement signature for in-scope engagements.
• Scope change: if a third party gains privileged access, handles regulated data, or becomes a critical dependency, re-run the harm-limiting controls.
• Software dependency introduction: when new libraries, images, or components enter builds, enforce integrity and provenance checks.
• Remote support enablement: require time-bounded access, approvals, and session logging for supplier access.

Deliverable: a written “SR-3(2) applicability decision” logic (simple decision tree is enough) that determines when the control set applies.

Step 4: Reduce targeting intelligence (limit what adversaries can learn)

Auditors rarely label this “targeting intelligence,” but it’s the intent. Concrete moves include:

• Limit external disclosure of supplier stack details where not required (public docs, job postings, support portals).
• Restrict internal visibility of high-risk supplier details to need-to-know roles.
• Classify supply chain artifacts (SBOMs, architecture diagrams, vendor access methods) and control distribution.

Evidence should show you have a classification/handling approach for supply chain-sensitive documentation and that staff follow it.

Step 5: Limit blast radius from supplier compromise

Operational controls that show real limitation of harm:

• Segment supplier access away from core admin planes and sensitive environments.
• Enforce least privilege and remove standing access.
• Require strong authentication and controlled endpoints for supplier access.
• Maintain the ability to disable supplier integrations quickly (kill switches, token revocation, account disable runbooks).

You don’t need perfection across all suppliers; you need a defined in-scope population and consistent execution.

Step 6: Test and exercise supplier incident paths

If an adversary targets your supply chain, your response depends on:

• Contact lists that work (named roles, monitored inboxes).
• Contractual notification requirements for suppliers.
• Internal playbooks to isolate integrations, rotate secrets, and suspend access.
• Tabletop exercises that include procurement and the business owner, not only security.

Produce a brief after-action report and track remediation to closure.

Required evidence and artifacts to retain

Keep artifacts that prove both design and operation:

Design artifacts

• SR-3(2) “organization-defined controls” list and rationale. ¹
• Control-to-owner mapping and RACI.
• Procedures/runbooks for each harm-limiting control.
• Applicability logic (in-scope third party criteria).

Operational artifacts

• Third-party intake records showing SR-3(2) checks completed (tickets, approvals).
• Access reviews for third-party accounts, including revocations.
• Logs or reports showing privileged vendor sessions are controlled and recorded (where applicable).
• CI/CD or repository evidence for dependency integrity controls (pipeline configurations, signed artifacts attestations).
• Incident communications tests, tabletop notes, after-action reports.

Retention approach

• Store evidence in a system with immutable history (ticketing + evidence repository) and a clear retention standard aligned to your audit cycle and contractual obligations.

Common exam/audit questions and hangups

Expect assessors to probe these areas:

1. “What are the ‘following controls’ you selected for SR-3(2)?”
   Hangup: teams cite a generic supply chain policy but cannot list the actual implemented controls. ¹

2. “Show me that the controls operate, not just that they exist.”
   Hangup: procedures exist, but no recurring evidence.

3. “Which third parties are in scope and why?”
   Hangup: inconsistent criticality definitions across Procurement, Security, and IT.

4. “How does your process change for privileged suppliers or software supply chain inputs?”
   Hangup: vendor access is handled ad hoc by IT admins.

5. “How do you limit harm if a key supplier is compromised tomorrow?”
   Hangup: no tested isolation/disable path for integrations or supplier access.

Frequent implementation mistakes (and how to avoid them)

Mistake	Why it fails	What to do instead
Treating SR-3(2) as a policy-only requirement	Policy doesn’t show harm limitation in production	Define controls, implement gates, retain operating evidence. 1
“All third parties are high risk”	You can’t execute consistently	Define tiers; apply the SR-3(2) control set to the highest-impact group first.
No owner for cross-functional steps	Controls stall between Procurement, IT, Security	Assign accountable owners and backup owners in a single mapping. 1
Relying on supplier assurances alone	Doesn’t reduce your blast radius	Add technical controls: segmentation, least privilege, rapid disable, monitored access.
Evidence scattered across email and spreadsheets	Hard to produce in audit	Centralize evidence in a system of record; require ticket IDs for approvals and reviews.

Enforcement context and risk implications

No public enforcement cases were provided in the source catalog for SR-3(2). The practical risk is assessment failure due to weak evidence and unclear “organization-defined” control selection, plus real-world exposure where a supplier compromise propagates into your environment. ¹

Practical 30/60/90-day execution plan

You asked for speed. Use this as an operator’s plan, and adjust scope to your highest-impact suppliers and dependencies.

First 30 days (stand up the control)

• Define your SR-3(2) control set (“following controls”) and get sign-off from Security + Procurement + system owners. ¹
• Publish an applicability decision tree for which third parties and components are in scope.
• Create the mapping: owner, procedure, and evidence artifacts for each selected control. ¹
• Pick a single evidence repository location and naming standard.

Days 31–60 (operate on the highest-risk slice)

• Apply SR-3(2) gates to new third-party intake and scope changes for the top criticality tier.
• Implement or tighten vendor access controls for privileged suppliers (approval, time-bounding, logging).
• Add “disable integration / rotate secrets” runbooks for critical third-party connections.
• Run one tabletop exercise that includes a supplier compromise scenario; capture actions and gaps.

Days 61–90 (expand and make it repeatable)

• Expand control execution to the next tier of third parties and key software dependencies.
• Add recurring reviews (access review cadence, supplier notification testing cadence) and automate evidence capture where possible.
• Perform an internal mini-assessment: sample several third parties and prove the full chain from applicability decision to evidence.

Frequently Asked Questions

What does “limitation of harm” mean in SR-3(2) in practical terms?

It means you implement safeguards that reduce the impact of supply chain targeting and compromise, and you can prove those safeguards run. You must define which controls you use as your organization-defined set. ¹

Do I have to apply SR-3(2) to every third party?

No. You should define applicability criteria and apply the SR-3(2) control set to the third parties and dependencies where compromise would cause the most harm. Document the criteria and keep it consistent.

What evidence is most persuasive to auditors for SR-3(2)?

Evidence that the controls operate: intake tickets, approvals, access review outputs, session logs for privileged supplier access, and incident exercise records. A mapping from SR-3(2) to owners, procedures, and artifacts reduces back-and-forth. ¹

How do we handle the “{{ insert: param, sr-03.02_odp }}” parameter if our program doesn’t have one yet?

Treat it as a required program decision: write down the list of harm-limiting controls you’re adopting for SR-3(2), then route it for approval. Without this, you can’t show what you “employ” for SR-3(2). ¹

We have strong third-party questionnaires. Is that enough to meet SR-3(2)?

Questionnaires help with due diligence, but SR-3(2) expects harm-limiting controls that reduce blast radius and targeting value in your environment. Pair questionnaires with technical and operational gates like access restrictions and integration kill switches.

Where does Daydream help most with SR-3(2)?

Daydream is useful where teams fail audits: mapping SR-3(2) to owners, procedures, and recurring evidence, then tracking execution across third parties and systems. That closes the “we do it, but can’t prove it” gap. ¹

Footnotes

1. NIST SP 800-53 Rev. 5 OSCAL JSON

2. NIST SP 800-53 Rev. 5