Quick-reference card
| Field | Value |
|---|---|
| Control ID | SC-43 |
| Control title | Usage Restrictions |
| Framework | NIST SP 800-53 Revision 5 |
| Control family | System and Communications Protection |
| Baseline(s) | Not assigned to any baseline |
| Implementation level | Organization and system |
| Relevance | First Party and Third Party |
| Risk severity | Low |
What this control requires
SC-43 requires organizations to define usage restrictions and implementation guidelines for system components, then authorize, monitor, and control how those components are used. This control targets components that can introduce risk when left unmanaged, including mobile devices, wireless access points, mobile code, and wired or wireless peripherals like printers, scanners, and optical devices.
In practice, this means you need documented rules that spell out which system components your workforce can use, under what conditions, and with what safeguards. Without these restrictions, organizations end up with an expanding inventory of devices and technologies connected to their environment with no consistent governance over how they operate or what data they can access.
The control also requires active oversight. Establishing usage restrictions on paper isn’t enough. You must authorize each component’s use within the system, monitor how components behave in your environment, and enforce controls that prevent unauthorized or risky usage patterns from taking root.
Why it matters
Most organizations accumulate system components faster than they can govern them. New devices, wireless peripherals, and mobile technologies enter the environment through procurement, BYOD policies, and shadow IT, often without formal usage restrictions in place. SC-43 exists to close this gap before ungoverned components become entry points for compromise or compliance failures.
The compliance risk here is structural, not dramatic. Without documented usage restrictions and implementation guidelines, auditors have no evidence that your organization has considered which components pose risk or how you’ve decided to manage them. That gap affects your overall NIST SP 800-53 posture even though SC-43 isn’t assigned to a baseline, because related controls like AC-18 and AC-19 depend on these foundational restrictions being in place.
Specifically, the absence of usage restrictions creates two problems at once. First, your authorization process breaks down because there’s no defined standard to authorize against. Second, monitoring becomes reactive rather than proactive, since you can’t detect policy violations when no policy exists.
Where this breaks down most often is in peripheral management. Printers, scanners, copiers, and similar devices are frequently treated as low-risk infrastructure and excluded from security governance entirely. Attackers know this. Organizations that skip usage restrictions for these components leave gaps that are difficult to detect through standard vulnerability management.
What attackers exploit
- Unmanaged wireless access points that bypass boundary protections and network segmentation
- Mobile devices connecting without authorization requirements or configuration baselines
- Peripheral devices like network-connected printers and scanners used as pivot points into internal networks
- Mobile code executing without restrictions, enabling malicious payloads to run on authorized systems
- Shadow IT components that operate outside monitoring coverage and lack usage guidelines
How to implement
The most common failure mode with SC-43 isn’t a lack of policy documents. It’s that organizations write generic acceptable use policies without tying specific restrictions to specific component categories, leaving implementation guidelines so broad that they can’t be meaningfully enforced or audited.
For your organization
Start by inventorying the system component categories that SC-43 covers in your environment. This inventory should include mobile devices, wireless access points, mobile code technologies, and wired or wireless peripherals such as printers, scanners, copiers, and optical devices. Don’t limit the scope to IT-managed assets. Include components that business units may have introduced independently.
For each component category, document specific usage restrictions that address how, when, where, and by whom the component can be used. These restrictions should reference your organization’s risk tolerance and any regulatory requirements that apply. Avoid writing a single blanket statement that covers all components identically. The restrictions for mobile code execution should look different from those governing wireless peripheral access.
Pair each set of restrictions with implementation guidelines that translate policy into operational practice. These guidelines should cover configuration requirements, enrollment procedures, approval workflows, and any technical controls that enforce the restrictions automatically. Automated enforcement reduces the monitoring burden and creates audit-ready evidence.
Build an authorization process that requires formal approval before any covered component can connect to or operate within the system. Maintain authorization records that capture who approved the component, under what conditions, and when the authorization was last reviewed.
Finally, implement monitoring that can detect both unauthorized component usage and deviations from approved usage patterns. Your system audit records and monitoring logs serve as the primary evidence that SC-43 is operating effectively. Review these records regularly and document the review cadence in your system and communications protection policy.
For your vendors
When assessing a vendor’s SC-43 implementation, focus on whether they can demonstrate structured governance over system component usage rather than a generic acceptable use policy.
Request the vendor’s system and communications protection policy and look for sections that define usage restrictions for specific component categories. A mature vendor will have separate restrictions for mobile devices, wireless access, mobile code, and peripheral technologies rather than a single policy that treats all components the same way.
Ask the vendor to provide their implementation guidelines alongside the restrictions. The guidelines should show how restrictions translate into technical and procedural controls. If a vendor can produce the policy but not the implementation guidelines, that’s a red flag indicating the restrictions may exist on paper without operational enforcement.
Review the vendor’s authorization records for system components. You want to see a defined approval workflow with evidence that authorizations are granted, reviewed, and revoked systematically. Vendors who can’t produce authorization records likely lack the formal process SC-43 requires.
Request evidence of monitoring and audit activity. The vendor should be able to provide system monitoring records or audit logs that demonstrate ongoing oversight of component usage. Look for regular review cadences rather than ad-hoc monitoring, and verify that the vendor has a process for detecting and responding to unauthorized component usage.
Ask these questions during your vendor assessment:
- What categories of system components are covered by your usage restrictions?
- How are usage restrictions enforced technically rather than through policy alone?
- Can you provide authorization records for system components currently in use?
- How often do you review and update your usage restrictions and implementation guidelines?
- What monitoring capabilities detect unauthorized component usage in your environment?
Evidence examples
| Evidence Type | Example Artifact |
|---|---|
| Usage restriction policy | System and communications protection policy defining usage restrictions for mobile devices, wireless access, mobile code, and peripherals by component category |
| Implementation guidelines | Procedures addressing configuration requirements, enrollment workflows, and technical controls for each covered component category |
| Authorization records | Approval logs documenting who authorized each system component, under what conditions, and when authorization was last reviewed |
| Monitoring and audit logs | System monitoring records and audit logs capturing component usage patterns, policy violations, and unauthorized access attempts |
| Component inventory | Asset register listing all system components subject to usage restrictions, including classification and risk rating |
| Review records | Documentation of periodic usage restriction reviews with update history and stakeholder sign-off |
Cross-framework mapping
No cross-framework mappings have been configured for this control.
Related controls
- AC-18 — Wireless Access: Governs how wireless access points and connections are authorized and protected, directly relying on the usage restrictions SC-43 defines for wireless components.
- AC-19 — Access Control for Mobile Devices: Establishes access control requirements specific to mobile devices, complementing the broader usage restrictions and implementation guidelines SC-43 requires for these components.
- CM-06 — Configuration Settings: Defines configuration baselines for system components, providing the technical enforcement layer that supports SC-43 usage restrictions.
- SC-07 — Boundary Protection: Controls information flow at system boundaries, intersecting with SC-43 where usage restrictions govern which components can operate across those boundaries.
- SC-18 — Mobile Code: Addresses restrictions on mobile code technologies specifically, applying the usage restriction and monitoring framework SC-43 establishes at the component category level.
Frequently asked questions
What is NIST SP 800-53 SC-43?
SC-43 is the NIST SP 800-53 control that requires organizations to establish usage restrictions and implementation guidelines for system components, then authorize, monitor, and control how those components are used. It covers mobile devices, wireless access, mobile code, and wired or wireless peripherals. The control ensures that only authorized system use occurs and that organizations maintain ongoing oversight of component behavior within their environment.
What happens if SC-43 is not implemented?
Without SC-43, organizations lack documented usage restrictions for system components, which means there’s no baseline to authorize against and no standard to monitor for violations. Auditors will flag the absence of implementation guidelines and authorization records as a governance gap, even if individual component controls exist elsewhere. The downstream impact is that related controls like AC-18 and AC-19 lose their policy foundation, weakening your overall system and communications protection posture.
How do you audit SC-43?
Auditing SC-43 starts with reviewing the system and communications protection policy to confirm that usage restrictions exist for each category of system component in scope. From there, examine the implementation guidelines to verify that restrictions translate into enforceable procedures. Check authorization records to confirm that system components are formally approved before deployment, and review system monitoring records and audit logs to verify that ongoing oversight detects unauthorized or non-compliant component usage.
What system components require usage restrictions?
SC-43 applies to all system components that can introduce risk, including mobile devices, wireless access points, mobile code, and wired or wireless peripherals such as copiers, printers, scanners, and optical devices. The scope isn’t limited to these examples. Any component with the potential to cause damage to the system or facilitate unauthorized access should be covered by your usage restrictions and implementation guidelines.