SR-4(2): Track and Trace

SR-4(2): Track and Trace requires you to assign and maintain unique identifiers for the systems and critical components you name in scope, so you can track them through the supply chain from source to deployment. Operationalize it by defining scope, selecting an ID standard, embedding IDs into procurement/receiving/configuration workflows, and retaining traceability evidence. ¹

Key takeaways:

• Define exactly which “systems and critical system components” are in scope, then freeze that scope in writing.
• Make unique identification real in operations: procurement records, receiving logs, CMDB/asset inventory, and change control must all carry the same IDs.
• Auditors look for end-to-end traceability proof, not a policy statement. ²

The sr-4(2): track and trace requirement is a supply chain control: it forces disciplined identification of specific systems and critical components so you can follow them through purchasing, delivery, staging, deployment, replacement, and retirement. If you cannot uniquely identify a component, you cannot reliably answer basic incident questions such as “Where else is this part deployed?” or “Was this unit sourced through an approved channel?”

SR-4(2) is written as a targeted requirement. You must decide what is “the following systems and critical system components” for your environment, then establish and maintain unique identification for that defined set. This is where many programs stall: teams either try to tag everything (and fail operationally), or tag nothing material (and fail in assessment).

This page gives requirement-level implementation guidance for a Compliance Officer, CCO, or GRC lead. You will leave with: a scoping decision method, a buildable workflow across procurement and IT/OT asset management, the evidence package to retain, and a practical execution plan you can hand to control owners.

Regulatory text

Requirement (excerpt): “Establish and maintain unique identification of the following systems and critical system components for tracking through the supply chain: {{ insert: param, sr-04.02_odp }}.” ¹

Operator interpretation of the text:

• “Establish” means you must define an identification approach, assign ownership, and implement it in real processes (not just on paper).
• “Maintain” means the identifiers persist and stay accurate across lifecycle events: purchase, receipt, inventory, deployment, patch/repair, transfer, and disposal.
• “Unique identification” means an identifier that distinguishes one system/component instance from all others in scope (for example: asset tag ID tied to serial number, or a logical ID tied to a cloud resource).
• “Tracking through the supply chain” means the ID must connect supply chain events and records, not only internal IT inventory.

Your job: fill in the organization-defined parameter (the “following systems and critical system components”) with a scoped list, then prove those items are uniquely identified and traceable through supply chain records and internal inventories. ²

Plain-English interpretation (what SR-4(2) really expects)

You need a reliable way to answer, on demand:

1. What exactly did we buy or receive (down to the instance)?
2. Where did it come from and through which channels?
3. Where is it now, and what is it connected to?
4. If a supplier, model, lot, firmware, or part is compromised, where else do we have it?

SR-4(2) is less about “labels on boxes” and more about traceability you can execute during a recall, vulnerability disclosure, counterfeit suspicion, or incident response.

Who it applies to (entity and operational context)

SR-4(2) is commonly applied in:

• Federal information systems and the organizations operating them. ¹
• Contractor systems handling federal data, including cloud, SaaS, and managed service environments supporting federal workloads. ¹

Operational contexts where SR-4(2) becomes concrete:

• Hardware procurement and receiving (servers, network gear, endpoints, OT controllers).
• Software supply chain (commercial software, open-source packages, container images) where you can uniquely identify builds/versions and provenance.
• Cloud infrastructure (unique IDs for accounts, subscriptions, projects, resources) when those resources are “systems” in your boundary.

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

Step 1: Define “systems and critical system components” in scope (your SR-4(2) parameter)

Create a short, controlled list that a control owner can implement. Practical scoping methods:

• Mission impact lens: systems that support high-impact services, regulated workloads, or safety-relevant operations.
• Connectivity lens: components with privileged access paths (identity, network, management planes).
• Replaceability lens: components that, if counterfeit or tampered with, are hard to detect or expensive to remediate.

Deliverable: SR-4(2) Scope Statement that lists item categories and examples (e.g., “production firewalls,” “hypervisors,” “HSMs,” “build pipeline runners”), plus inclusions/exclusions and rationale. Tie it to your system boundary documentation if you maintain one. ²

Step 2: Choose an identifier scheme that survives real operations

Pick a scheme that works across procurement, receiving, asset inventory, and decommissioning.

Common patterns:

• Hardware: internal asset tag ID mapped to manufacturer serial number, model, and (where available) lot/batch; store all fields.
• Software: internal software/component ID mapped to supplier, product name, version, build hash, and approval record.
• Cloud resources: provider-native resource IDs plus an internal “system/component” identifier that matches your inventory taxonomy.

Rules to set in writing:

• What makes an ID “unique” for each asset class.
• Who creates IDs and when (PO creation, receiving, first deployment).
• How duplicates are prevented and detected.

Deliverable: Unique Identification Standard (SR-4(2)), a one-to-two page standard with examples. ¹

Step 3: Embed IDs into the supply chain workflow (don’t treat this as an IT-only control)

Map the end-to-end path and insert ID capture points:

1. Sourcing / supplier selection

   • Require suppliers/resellers to provide serials, part numbers, software bill of materials (if applicable), and shipment identifiers in advance when feasible.
   • Ensure purchase orders include fields for your internal ID (or a placeholder that becomes the ID at receipt).

2. Procurement

   • Configure procurement tooling (ERP/procurement platform) to store: supplier, channel, PO, item description, serial/part number, and the internal unique ID once assigned.

3. Receiving

   • At receiving, verify serial/part numbers against PO/ASN and record condition and custody.
   • Assign or affix internal asset tags for in-scope hardware if not already tagged.
   • For software/media, record package identifiers, checksums, and source.

4. Inventory / CMDB

   • Ensure the CMDB/asset inventory has required fields and validation (no “unknown” serials for in-scope classes without an exception record).
   • Link the inventory record to procurement and receiving artifacts.

5. Deployment / change management

   • Make the unique ID a required field in change tickets for install/replace actions.
   • Record location, environment, owner, and dependencies (what it connects to).

6. Maintenance / RMA

   • Track repair and replacement events by unique ID, including chain of custody and return disposition.

7. Disposal

   • Close the loop: retirement date, disposition method, and evidence of disposal mapped to the unique ID.

Deliverable: SR-4(2) Traceability Workflow Map (a swimlane diagram is ideal) and updated SOPs for procurement/receiving/asset management. ²

Step 4: Define exceptions and compensating controls

You will have gaps: legacy gear, emergency purchases, third-party managed assets, or cloud resources created ad hoc.

Set:

• An exception process with expiry, approver, and remediation plan.
• Compensating controls (for example: tighter monitoring, additional supplier verification steps, quarantine on receipt) aligned to your risk model.

Deliverable: SR-4(2) Exception Register with approvals and closure tracking. ²

Step 5: Prove ongoing operation (not a one-time tagging project)

Operational tests you can run:

• Sample in-scope assets and confirm you can trace from inventory record back to PO and receiving.
• Sample recent purchases and confirm identifiers were assigned at the required step.
• Validate that replacements and RMAs preserve traceability.

Deliverable: Quarterly (or scheduled) SR-4(2) Traceability Test Results with findings and fixes tracked. ²

Required evidence and artifacts to retain

Auditors usually accept a package that shows design + operation:

Governance / design

• SR-4(2) Scope Statement (systems/components in scope)
• Unique Identification Standard (data fields, uniqueness rules, ownership)
• Traceability Workflow Map + SOPs (procurement, receiving, inventory, change)

Operational records (samples over time)

• Purchase orders and invoices showing item details and supplier/channel
• Receiving logs with serial/part number capture and custody notes
• CMDB/asset inventory exports for in-scope classes (with required fields populated)
• Change tickets referencing the unique IDs for install/replace events
• RMA/repair records linked to unique IDs
• Disposal/decommission records linked to unique IDs
• Exception Register entries with approvals and closure evidence

Assessment readiness tip: pre-build an “evidence binder” organized by asset class, with cross-links (PO → receiving → CMDB → change ticket). ¹

Common exam/audit questions and hangups

Expect questions like:

• “Show me your scoped list for SR-4(2). Who approved it?” ²
• “Pick a firewall in production. Trace it back to procurement and receiving records.”
• “How do you prevent duplicate asset IDs? What happens if a serial number is missing?”
• “How do you track cloud resources or virtual appliances where there is no physical serial?”
• “How do you handle third-party managed infrastructure where you don’t control receiving?”

Hangups that slow audits:

• CMDB records exist but don’t link to procurement/receiving artifacts.
• Different teams use different identifiers (procurement uses PO line item; IT uses hostname; security uses a scanner ID) with no crosswalk.

Frequent implementation mistakes and how to avoid them

1. Mistake: tagging everything instead of scoping critical components.
   Fix: publish a scoped list with clear rationale and expand iteratively after you can pass a traceability test.

2. Mistake: treating unique ID as “hostname.”
   Hostnames change. Use stable identifiers (asset tag/serial/resource ID) and store hostname as an attribute.

3. Mistake: IDs exist, but only in one system (e.g., CMDB).
   Fix: require the ID in procurement and change management fields. Create a crosswalk table if you can’t integrate systems quickly.

4. Mistake: “maintain” is ignored.
   Fix: add lifecycle triggers (replace, repair, move, dispose) and require updates as part of the ticket closure checklist.

5. Mistake: unmanaged third parties create blind spots.
   Fix: contractually require reporting of identifiers and lifecycle events for in-scope components, and test those reports.

Enforcement context and risk implications

No public enforcement cases were provided for SR-4(2) in the supplied source catalog, so you should treat this as an assessment and mission risk driver rather than a penalty-cited enforcement topic in this page. ¹

Risk implications you can explain to leadership without hype:

• Without traceability, vulnerability response becomes slower and less reliable because you cannot confidently identify affected instances.
• Counterfeit or tampered components are harder to detect and contain without provenance and custody records tied to unique IDs. ²

A practical 30/60/90-day execution plan

First 30 days (stand up the control)

• Assign a control owner across procurement + IT asset management (one accountable owner, multiple contributors).
• Draft and approve the SR-4(2) Scope Statement.
• Define the Unique Identification Standard and required data fields per asset class.
• Identify “system of record” locations: procurement tool, receiving log, CMDB/asset inventory, ticketing.

Days 31–60 (embed into workflows and start collecting evidence)

• Update procurement and receiving SOPs to capture identifiers at the right moment.
• Add required fields and validation rules to the CMDB/asset inventory for in-scope classes.
• Update change templates so install/replace actions require the unique ID.
• Build an exception process with an approver and an expiry requirement.

Days 61–90 (prove operation and close gaps)

• Run a traceability tabletop: select a small sample of in-scope assets and walk PO → receiving → inventory → deployment.
• Fix the top recurring defects (missing serials, inconsistent IDs, no link to purchase records).
• Package evidence for assessment: screenshots/exports + sample tickets + a short narrative that maps artifacts to SR-4(2).
• If you use Daydream, map SR-4(2) to a named control owner, documented procedure, and a recurring evidence checklist so the audit package is generated continuously, not assembled under deadline. ¹

Frequently Asked Questions

What counts as a “unique identifier” for SR-4(2)?

A stable identifier that distinguishes one instance from another within your defined scope, and that you can carry across procurement, receiving, inventory, and change records. For hardware, pair an internal asset tag with manufacturer serial; for cloud, store the provider resource ID plus your internal inventory ID. ²

Do we have to track every component we buy?

No. SR-4(2) is scoped to “the following systems and critical system components” that you define and approve as the organization-defined parameter. The control fails when the scope is undefined, unapproved, or disconnected from operations. ¹

How do we handle third-party managed environments where we can’t tag assets ourselves?

Put identifier reporting and lifecycle event reporting into the contract or SOW for in-scope components, then ingest those records into your inventory. Test the reports by sampling assets and tracing them to procurement/channel documentation.

We already have a CMDB. Why isn’t that enough?

A CMDB shows what you believe you operate; SR-4(2) expects traceability through the supply chain. You need links or crosswalks to procurement, receiving, and custody records, plus proof the identifiers are maintained across lifecycle events. ²

What’s the fastest way to get audit-ready if our data is messy?

Start with a narrow in-scope list, then build a crosswalk table that maps procurement identifiers (PO/line) to asset inventory identifiers (asset tag/serial/resource ID). Use that crosswalk as a temporary bridge while you fix workflow and system integrations.

How should we evidence “maintain” versus “establish”?

“Establish” is your approved scope and identification standard; “maintain” is operational proof across time, such as recent change tickets for replacements, updated inventory records, and exception closures tied back to unique IDs. ¹

Footnotes

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

2. NIST SP 800-53 Rev. 5