03.16.02: Unsupported System Components

To meet the 03.16.02: unsupported system components requirement, you must identify system components in your CUI environment that are end-of-life or otherwise vendor-unsupported, then either replace them, isolate them with compensating controls, or obtain a documented, time-bound risk acceptance with an upgrade plan. Your evidence must show continuous detection, decision-making, and follow-through. ¹

Key takeaways:

• Keep an authoritative inventory that flags end-of-support (EOS) and end-of-life (EOL) status for every in-scope component.
• Define a repeatable disposition path: replace, isolate with compensating controls, or formally accept risk with deadlines and ownership.
• Auditors look for operational proof: tickets, exception approvals, network segmentation, and recurring reporting, not just policy.

Unsupported components are a predictable failure point in environments handling Controlled Unclassified Information (CUI). They stop receiving security patches, their vulnerabilities become well-known, and they tend to persist because they “still work.” Requirement 03.16.02 exists to break that pattern by forcing you to treat supportability as a security control, not an IT hygiene goal. ¹

For a Compliance Officer, CCO, or GRC lead, the fastest path to operationalize this requirement is to turn “unsupported” into a measurable condition tied to (1) a complete system inventory, (2) a clear rule for what counts as unsupported, and (3) an enforced workflow that ends with remediation or an approved exception. The key is consistency: the same detection method, the same decision criteria, and the same evidence package every time.

This page gives you requirement-level implementation guidance you can hand to IT, security operations, and system owners, then validate through artifacts that hold up in assessment for NIST SP 800-171 Rev. 3-aligned programs. ¹

Regulatory text

Requirement 03.16.02: Unsupported System Components — NIST SP 800-171 Rev. 3 includes requirement 03.16.02 addressing unsupported system components. ¹

Operator interpretation of what you must do:
You must have a managed process to prevent unsupported components from operating in the environment that processes, stores, or transmits CUI, or you must control them through documented exceptions that reduce risk and drive timely replacement. Evidence must demonstrate ongoing identification of unsupported components and tracked actions to remove, upgrade, or formally accept the risk with compensating controls. ¹

Plain-English interpretation (what this means in practice)

“Unsupported” means the publisher or manufacturer no longer provides security updates, fixes, or technical support for a component you rely on to protect CUI. In practice, this includes:

• Operating systems past vendor support dates
• Unpatched applications because the version is out of maintenance
• Firmware on network/security appliances that can’t be updated because the hardware is EOL
• Databases, hypervisors, and endpoint agents that are out of support
• Embedded systems and “appliances” that IT forgot were still in scope

Your compliance goal is not perfection on day one. Your goal is control: you can quickly answer (a) what is unsupported, (b) where it is, (c) who owns it, (d) what you’re doing about it, and (e) when risk ends.

Who it applies to

Entity scope: Organizations operating nonfederal systems that handle CUI, including federal contractors and subcontractors with CUI obligations. ¹

Operational scope (what systems):

• Any system components within the CUI boundary (the “CUI environment”), including cloud workloads, endpoints, servers, network devices, and security tooling that directly protect or route CUI.
• Shared services that materially affect the confidentiality of CUI (identity, logging, endpoint protection), even if managed by a third party, because you still need assurance and evidence.

Teams you need engaged:

• IT operations (asset inventory, lifecycle management)
• Security operations (vulnerability scanning, detection)
• System owners/business app owners (risk decisions)
• Procurement/vendor management (renewals, support contracts)
• GRC/compliance (exception governance and evidence)

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

Step 1: Define “unsupported” and the decision rule

Create a short standard (1–2 pages) that defines:

• Unsupported criteria: vendor EOL/EOS, end of maintenance, or no security patches available.
• In-scope components: OS, apps, databases, hypervisors, network appliances, endpoint agents, firmware, containers/base images as applicable.
• Disposition options: remediate, isolate with compensating controls, or exception with risk acceptance. Tie this standard to your system security plan (SSP) and your change management process so it is enforceable. ¹

Step 2: Build an authoritative component inventory for the CUI boundary

You need an inventory that is “assessment-ready,” meaning it is complete enough to drive action and defend scope. Minimum fields:

• Asset/component name, type, and environment (prod/dev if relevant to CUI)
• Owner (named person or role)
• Version/build, last update date, and support status (supported/unsupported/unknown)
• Support/EOL reference (vendor bulletin link or contract/support entitlement reference)
• Location (network segment, cloud account/subscription, site)
• CUI relevance (inside boundary, supporting boundary, out of scope)

If you already maintain a CMDB, use it, but validate it with discovery sources (endpoint management, cloud inventory, network scans). The common failure is a CMDB that is “accurate on paper” but missing real devices. ¹

Step 3: Implement continuous detection for EOS/EOL status

Operationally, you need recurring detection that flags unsupported items without waiting for a human to notice. Common patterns:

• Endpoint/MDM reports for OS and application versions
• Vulnerability scanner results that indicate EOL software
• Cloud posture/inventory tools for base images and managed service versions
• Network discovery for appliances and firmware

Define who reviews the findings, how often they review, and what triggers escalation (for example, any unsupported component that touches the CUI boundary). Keep the output reports. ¹

Step 4: Triage and assign owners with deadlines

Create a simple workflow:

1. Confirm unsupported status (avoid false positives).
2. Assess exposure: internet-facing, privileged role, stores/transmits CUI, lateral movement potential.
3. Assign remediation to the system owner with a change ticket.
4. Track to closure with leadership visibility.

A tight triage template reduces debates later. Require: component, reason unsupported, affected systems, risk notes, proposed fix, target completion date, and rollback plan.

Step 5: Remediate or isolate with compensating controls

Preferred action is replacement/upgrade. When immediate replacement is not feasible, require compensating controls that reduce likelihood and blast radius, such as:

• Network segmentation with explicit allow-listing
• Removal of internet exposure
• Restrict admin access, enforce MFA, and reduce privileges
• Increased monitoring and alerting for the asset
• Virtual patching or strict WAF rules where applicable
• Application allow-listing on the host (if feasible)

Document which controls you applied and why they are sufficient for the limited time window. ¹

Step 6: Govern exceptions (risk acceptance) tightly

Unsupported components often linger because exceptions are informal. Your exception process should require:

• Named executive/system owner approval
• Reason replacement is not feasible yet
• Compensating controls implemented
• A time-bound plan to eliminate the exception (upgrade, replace, decommission)
• Re-approval if the timeline slips

Keep exceptions rare and visible. Treat them as open risk items that must be reviewed regularly with accountability. ¹

Step 7: Operationalize evidence collection (make it repeatable)

Auditors will ask for proof that your process runs consistently. Build a recurring evidence package:

• Inventory export for in-scope components with support status
• Detection reports showing EOL/EOS findings
• Tickets proving remediation actions
• Exception register entries with approvals and compensating controls
• Meeting notes or dashboards showing periodic review

Tools can help here. Daydream is often introduced at this stage to centralize control mapping, schedule recurring evidence pulls, and keep exception workflows and artifacts tied directly to 03.16.02 so you are not rebuilding the story each assessment cycle. ¹

Required evidence and artifacts to retain

Use this as your minimum “audit binder” for the 03.16.02: unsupported system components requirement:

Artifact	What “good” looks like	Owner
Supported/unsupported definition standard	Clear criteria, scope, disposition options, exception rules	GRC + IT
CUI boundary component inventory	Version, owner, support status, location, CUI relevance	IT Ops
EOS/EOL detection outputs	Reports showing identification of unsupported items	SecOps
Remediation tickets/changes	Traceable from finding → change → closure	IT Ops
Exception register	Approvals, compensating controls, end date, review notes	GRC
Compensating control configs	Segmentation rules, firewall policies, MFA enforcement evidence	SecOps/Network
Periodic review evidence	Dashboard screenshots, meeting minutes, sign-offs	GRC

Common exam/audit questions and hangups

Expect these questions in assessments aligned to NIST SP 800-171 Rev. 3. ¹

1. “Show me how you know what’s unsupported.”
   Hangup: you rely on tribal knowledge. Fix: produce inventory plus scanner/MDM reports.

2. “Is your inventory complete for the CUI boundary?”
   Hangup: endpoints and lab systems missing. Fix: reconcile CMDB against discovery.

3. “What do you do when you find something unsupported?”
   Hangup: ad hoc response. Fix: show a documented workflow and tickets.

4. “Prove exceptions are controlled.”
   Hangup: email approvals only. Fix: maintain an exception register with compensating controls and review cadence.

5. “How do third parties factor in?”
   Hangup: “the provider handles it” without evidence. Fix: require third-party attestations or contractual support commitments and map impacted components.

Frequent implementation mistakes (and how to avoid them)

• Mistake: Treating this as a policy-only control.
  Avoid it by making detection and ticketing mandatory, with recurring reports retained.

• Mistake: No owner field in inventory.
  Avoid it by requiring a named accountable owner for each component. No owner, no deployment.

• Mistake: “Unsupported” determined once per year.
  Avoid it by tying EOL checks to change management and recurring vulnerability scanning outputs.

• Mistake: Exceptions with no compensating controls.
  Avoid it by defining a minimum compensating-control baseline before any exception can be approved.

• Mistake: Scoping errors (missing supporting systems).
  Avoid it by including identity, logging, and network/security devices that protect or route CUI, not only servers that “store files.”

Enforcement context and risk implications

No public enforcement cases were provided in the source catalog for this requirement, so this page does not list enforcement examples.

Operationally, unsupported components increase the likelihood that known vulnerabilities remain exploitable and unpatched, which raises the risk of CUI compromise. From an assessment standpoint, unsupported components are also “easy findings” because they are externally verifiable against vendor lifecycle notices, and auditors expect you to have a deterministic answer backed by inventory and records. ¹

Practical 30/60/90-day execution plan

You can run this as a focused program without boiling the ocean. The objective is to move from uncertainty to controlled execution.

First 30 days (stabilize and get visibility)

• Publish your “unsupported component” standard and exception workflow.
• Define the CUI boundary and list in-scope component categories.
• Pull initial inventories from CMDB, MDM/endpoint tooling, cloud inventory, and vulnerability scanning.
• Create the first unsupported-component register and assign owners for each item. ¹

Next 60 days (drive remediation and prove the workflow)

• Prioritize and remediate the highest-exposure unsupported items (internet-facing, privileged, CUI-adjacent).
• Implement compensating controls for items awaiting replacement (segmentation, access tightening, monitoring).
• Stand up the exception register with approvals and review notes.
• Produce your first recurring evidence package tied to 03.16.02. ¹

By 90 days (make it repeatable and assessment-ready)

• Integrate EOS/EOL checks into change management and procurement (new purchases must have supportability data).
• Establish recurring review reporting to leadership (unsupported items, exceptions, remediation progress).
• Run an internal mini-assessment: sample unsupported findings and walk them end-to-end from detection to closure.
• If you need less manual effort, configure Daydream to map the requirement to your control set and automate recurring evidence collection and exception tracking. ¹

Frequently Asked Questions

What counts as a “system component” for 03.16.02?

Treat any part of the system that processes, stores, transmits, or protects CUI as a component: OS, applications, databases, hypervisors, network appliances, endpoint agents, and firmware. Your inventory and support-status tracking should match that scope. ¹

If a component is unsupported but “behind the firewall,” can we keep it?

You can keep it only if you control the risk through compensating controls and a documented exception with a replacement plan. Auditors will expect isolation and monitoring evidence, not verbal assurances. ¹

Do we need to eliminate every unsupported component immediately?

The requirement is operational control over unsupported components, which typically means timely remediation or a time-bound, approved exception with compensating controls. Your artifacts must show active management and follow-through. ¹

How do we handle third-party managed services where we don’t control versions?

Treat supportability as a third-party assurance requirement: contract for supported versions, request evidence/attestations, and document how the service remains supported within your CUI boundary. Keep the third party’s evidence linked to your inventory and exceptions. ¹

What’s the minimum evidence auditors will accept for an exception?

Keep an exception record with owner approval, rationale, compensating controls implemented, and a plan to remove the unsupported component. Pair it with technical evidence like segmentation rules, restricted access settings, and monitoring alerts. ¹

We have legacy hardware that can’t be upgraded. What’s a defensible path?

Document that upgrades are unavailable, isolate the device, restrict access to only required systems, and monitor it closely while executing a replacement or decommission plan. Your exception should be explicit about why it exists and what ends it. ¹

Footnotes

1. NIST SP 800-171 Rev. 3