SC-42(3): Prohibit Use of Devices

SC-42(3): Prohibit Use of Devices requires you to block the use of specified devices in defined system areas or situations to prevent eavesdropping, data capture, or unintended emission of information. To operationalize it fast, define the banned device list and scope, enforce the prohibition with technical controls (where possible), backstop with physical and procedural controls, and keep assessor-ready evidence. ¹

Key takeaways:

• Define “prohibited devices” and the exact places/systems where the prohibition applies, then publish it as an enforceable standard. ¹
• Implement layered enforcement: endpoint controls + network controls + facility controls + user workflow. ²
• Audits hinge on proof of enforcement and exceptions, not policy language alone. ²

“Prohibit use of devices” sounds simple until you have to implement it across modern work patterns: hybrid staff, third parties onsite, shared lab spaces, and a mix of managed and unmanaged endpoints. SC-42(3) exists to reduce the risk that devices capable of recording, transmitting, or otherwise capturing information undermine confidentiality through monitoring, audio/video capture, or exploitation of emitted signals. The practical challenge is that “devices” includes more than USB storage; it can include personal phones, smartwatches, wireless peripherals, cameras, and specialized tools that show up in engineering and operations.

For a Compliance Officer, CCO, or GRC lead, the fastest path is to translate SC-42(3) into three enforceable decisions: (1) which devices are prohibited, (2) where and when they are prohibited, and (3) how the organization will detect and stop violations. Then you align ownership (Security, IT, Facilities, and system owners), implement controls with logs, and set up an exceptions process that does not become a loophole.

This page gives requirement-level implementation guidance you can drop into your control library and turn into testable procedures and evidence packets tied to the sc-42(3): prohibit use of devices requirement. ¹

Regulatory text

Control excerpt (as provided): “NIST SP 800-53 control SC-42.3.” ¹

Operator interpretation you can implement: SC-42(3) is an enhancement to SC-42 (Sensor Capability and Data) that expects you to prohibit the use of certain devices in contexts you define as sensitive (facilities, rooms, system components, or operating modes). Your implementation must be concrete enough that an assessor can identify:

• the specific device types that are prohibited,
• the scoped environments where the prohibition applies, and
• the enforcement mechanisms and evidence that the prohibition is operating. ²

Plain-English interpretation (what this requirement really means)

You must prevent people from bringing in or using devices that can capture, store, or transmit sensitive information in places or workflows where that creates unacceptable risk.

In practice, SC-42(3) is commonly used to manage risk from:

• Recording and exfiltration (camera, microphone, removable media, rogue wireless).
• Unintended emissions and “listening” devices (wireless peripherals, smart devices).
• Third party access patterns (contractors, visitors, service techs) where device control is weaker.
• High-sensitivity environments (security operations, regulated processing areas, R&D labs). ²

Who it applies to

SC-42(3) is relevant to:

• Federal information systems and the teams operating them. ¹
• Contractor systems handling federal data (for example, environments supporting federal contracts) where NIST SP 800-53 is used as the control baseline. ¹

Operationally, it applies wherever your organization processes, stores, or transmits sensitive data and where device presence creates material confidentiality risk, including:

• data centers and network closets,
• SOC/NOC spaces,
• secure conference rooms,
• regulated production floors,
• admin consoles and jump hosts,
• build pipelines and signing systems,
• incident response “war rooms.” ²

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

1) Assign a control owner and define the enforcement boundary

• Name an accountable owner (often Security or IT) and a responsible implementer for each relevant facility or system boundary (Facilities for spaces, IT for endpoints, Network for wireless).
• Define the boundary in plain terms: rooms, subnets, system components, and workflows where restrictions apply.
  Deliverable: “SC-42(3) Prohibited Devices Standard” with scope and owners. ¹

2) Define the prohibited device list (by category, with examples)

Create a list that is specific enough to enforce and audit. Use categories with examples:

• Cameras/recording: standalone cameras, personal phones with cameras in secure rooms, webcams in restricted zones.
• Audio capture: voice recorders, smart assistants.
• Removable storage: USB mass storage, SD cards (including via adapters), external drives.
• Wireless radio: unauthorized Bluetooth peripherals, hotspots, rogue Wi‑Fi adapters.
• Wearables/IoT: smartwatches, smart glasses, tracking tags where inappropriate.
• Specialized tools: RF scanners, SDR devices, debugging dongles not explicitly approved.

Write it as “prohibited unless explicitly approved,” then define the approval path. ²

3) Choose enforcement methods (technical first, then physical and procedural)

Use layered controls so one gap does not break the requirement.

Endpoint controls (managed devices)

• Device control policies to block USB storage classes and unauthorized peripherals.
• OS controls restricting camera/mic access for specific roles or device profiles.
• Mobile device management restrictions for corporate phones used in restricted spaces.

Network controls

• Block unauthorized wireless access points; monitor for rogue SSIDs in sensitive areas.
• NAC policies limiting what can connect in restricted VLANs.
• Segmentation and “no BYOD” network zones.

Facility/physical controls

• Signage at entrances to restricted areas stating prohibited devices.
• Lockers or device drop points.
• Visitor escort procedures with device checks where justified by your risk assessment.

Procedural controls

• Access rules for third parties: contracts, onboarding briefings, and onsite rules.
• A clear incident path for violations: confiscation policy (if allowed), removal from area, and security ticketing.

Your goal is straightforward: prohibition that is observable and enforceable, not aspirational. ²

4) Define and run an exceptions process that does not turn into “everyone is exempt”

Most environments need exceptions (maintenance tools, assistive technology, incident response). Build an exceptions workflow with:

• requestor, device details, purpose, location, start/end dates,
• approval by system owner and Security,
• compensating controls (escorted use, temporary network access, logging),
• revocation and return requirements.

Keep exceptions time-bound and reviewable. ²

5) Train and operationalize the human workflow

• Train staff and frequent onsite third parties on prohibited device zones and “why.”
• Add security briefings to visitor check-in and contractor onboarding.
• Provide a low-friction alternative: approved loaner devices, managed peripherals, secure rooms with approved conferencing kits.

6) Test the control and keep it testable

Build a simple test plan that an internal auditor can repeat:

• verify endpoint policies are deployed to the in-scope fleet,
• attempt a USB mount on a test endpoint,
• validate rogue device alerting or periodic wireless scans where required,
• walk-through restricted areas for signage and controls,
• sample exceptions and confirm they match approvals and time bounds. ²

Required evidence and artifacts to retain

Auditors will ask for evidence that the prohibition exists, is communicated, and is enforced. Keep:

• Control mapping and ownership: RACI or control register entry tying SC-42(3) to owners and scope. ¹
• Prohibited Devices Standard: device categories, prohibited zones, enforcement methods, exception criteria.
• Technical evidence: screenshots/exports of endpoint device-control policies; MDM restriction profiles; NAC policies; wireless monitoring configuration; change tickets for deployments.
• Operational logs: alerts for blocked device events, rogue wireless detections, service desk tickets for violations, and resolution notes.
• Physical evidence: photos of signage, visitor check-in procedures, floor plans marking restricted zones, locker/drop-point procedures (if used).
• Exceptions register: approved exceptions with dates, approvers, and compensating controls.
• Training records: targeted training completion for staff with access to restricted zones; onboarding acknowledgement forms for third parties. ²

A practical tip: keep an “assessor packet” that you refresh on a cadence. Daydream is often used to map SC-42(3) to the control owner, the implementation procedure, and the recurring evidence artifacts so evidence collection does not become a quarterly scramble. ¹

Common exam/audit questions and hangups

1. “What devices are prohibited, exactly?”
   A list that says “unauthorized devices” without examples tends to fail.

2. “Where is this enforced?”
   Assessors expect a defined boundary: rooms, networks, systems, or operating modes.

3. “Show me enforcement, not policy.”
   They will ask for logs, configuration exports, and a violation ticket trail.

4. “How do you handle third parties and visitors?”
   Expect questions about check-in, escorting, and contractual rules.

5. “How do exceptions work?”
   A weak exceptions process is a common finding because it becomes permanent authorization by convenience. ²

Frequent implementation mistakes (and how to avoid them)

• Mistake: banning “USB” but ignoring phones, wearables, and wireless peripherals.
  Fix: write a device taxonomy and map each class to a control method (block, restrict, allow with approval).

• Mistake: relying on signage alone.
  Fix: pair signage with endpoint/network enforcement and ticketed response.

• Mistake: scoping the control to “the data center” only, while admins manage production from office laptops.
  Fix: scope by workflow and system access path (admin consoles, jump hosts, privileged endpoints).

• Mistake: unmanaged devices are allowed because “we can’t control them.”
  Fix: prohibit them in restricted areas and provide managed alternatives or controlled exception windows.

• Mistake: exceptions have no end date.
  Fix: require expiry and periodic review; force re-approval with a justification. ²

Enforcement context and risk implications

No public enforcement cases were provided in the source catalog for this requirement, so this page does not cite specific actions.

Risk-wise, SC-42(3) failures often show up as:

• preventable data exposure via recording devices in sensitive spaces,
• removable media introducing malware or enabling data theft,
• rogue wireless bridging secure networks to uncontrolled endpoints. ²

Treat this control as both a confidentiality safeguard and an operational discipline test: if you cannot enforce device restrictions in your most sensitive workflows, other technical controls tend to erode over time.

Practical execution plan (30/60/90-day)

First 30 days (stabilize scope and policy-to-control translation)

• Confirm in-scope systems, facilities, and workflows for SC-42(3). ²
• Publish the prohibited device categories list and the restricted zones list.
• Stand up an exceptions workflow and register (even if manual at first).
• Implement quick wins: signage, visitor acknowledgment, and a documented response path for violations.

Days 31–60 (implement technical enforcement and evidence capture)

• Roll out endpoint device controls for removable media and unauthorized peripherals on in-scope fleets.
• Configure network enforcement for restricted VLANs and baseline rogue wireless detection in sensitive areas.
• Create an evidence kit: policy docs, config exports, and a sample of logs/tickets.

Days 61–90 (operationalize, test, and audit-proof)

• Run a tabletop or walkthrough test of the restricted-zone process (staff, visitors, third parties).
• Sample and review exceptions; revoke stale approvals.
• Perform an internal audit-style check with repeatable test steps and remediate gaps.
• Convert recurring evidence into a scheduled task with owners and due dates; Daydream can track the owner, procedure, and recurring artifacts so you can answer assessors quickly. ¹

Frequently Asked Questions

Does SC-42(3) mean we must ban all personal devices everywhere?

No. You define the prohibited device types and the restricted contexts based on your system boundary and risk. The control expectation is that the prohibition is explicit, enforced, and evidenced in the scoped areas. ²

What counts as a “device” for SC-42(3)?

Treat “device” broadly: anything that can record, store, transmit, or introduce connectivity in a way that could expose data. Document categories and examples so enforcement and audits are consistent. ²

If we have endpoint DLP, do we still need prohibited-device controls?

DLP can help, but SC-42(3) is about preventing device use in sensitive contexts, not only detecting data movement. Auditors typically expect both policy and observable enforcement appropriate to the environment. ²

How do we handle contractors who need phones for MFA or on-call work?

Offer an approved path: either allow phones under defined conditions (for example, specific zones) or provide managed alternatives like dedicated tokens. Document the exception with compensating controls and a review/expiry. ²

What evidence is most persuasive to an assessor?

Configuration exports showing device restrictions, logs showing blocks or alerts, and a traceable exceptions register with approvals and expirations. Pair that with scoped documentation that states where the prohibition applies. ¹

How do we keep SC-42(3) from becoming a quarterly scramble before assessments?

Assign an owner, define recurring artifacts, and schedule evidence capture as routine operations. Many teams track this in a GRC system; Daydream is commonly used to map SC-42(3) to the owner, procedure, and recurring evidence artifacts. ¹

Footnotes

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

2. NIST SP 800-53 Rev. 5