Security requirement
Control physical access to system distribution and transmission lines within organizational facilities.
Discussion
Safeguarding measures applied to system distribution and transmission lines prevent accidental damage, disruption, and physical tampering. Such measures may also be necessary to prevent eavesdropping or the modification of unencrypted transmissions. Safeguarding measures used to control physical access to system distribution and transmission lines include disconnected or locked spare jacks, locked wiring closets, cabling protection with conduit or cable trays, and wiretapping sensors.
Implementation perspective
Treat Access Control for Transmission as a CUI protection outcome that must be reflected in the system boundary, documented implementation, operational behavior, and assessment evidence. Pay particular attention to physical access, facility protection, visitor accountability, and protection of system components that handle CUI.
- Confirm the requirement is in scope for the CUI system components, services, users, and external connections being assessed.
- Resolve every organization-defined parameter through an approved governance and tailoring process.
- Map each clause of the requirement to an accountable owner, implementation mechanism, and evidence source.
- Verify that inherited and shared implementations are supported by current provider evidence and responsibility boundaries.
- Collect evidence during normal operation and review changes, exceptions, and deficiencies on a risk-based cadence.
Questions to ask
- Which CUI assets, data flows, users, and services are protected by this requirement?
- Which portions are implemented locally, inherited, shared, or not applicable, and what evidence supports that determination?
- Do the system security plan, deployed configuration, operating process, and assessment evidence tell the same story?
- What change, incident, or threshold should trigger reassessment?
Evidence and validation
- badge and visitor logs
- physical access reviews
- facility diagrams and sensor records
- environmental and power test results
Common failure patterns
- logical controls undermined by physical access
- tailgating or visitor exceptions normalized
- critical infrastructure omitted from access reviews
- environmental alarms disconnected from response
Assessment objectives and methods
Assessment objectives (1)
- SR-03.10.8.
physical access to system distribution and transmission lines within organizational facilities is controlled.
Examine
- physical protection policy and procedures
- procedures for access control for transmission mediums
- system design documentation
- facility communications and wiring diagrams
- list of physical security safeguards applied to system distribution and transmission lines
- procedures for access control for display medium
- facility layout of system components
- list of output devices and associated outputs that require physical access controls
- actual displays from system components
- physical access control logs or records for areas containing output devices and related outputs
- system security plan
- other relevant documents or records
Interview
- personnel with physical access control responsibilities
- personnel with information security responsibilities
Test
- processes for access control for distribution and transmission lines
- mechanisms for supporting or implementing access control for distribution and transmission lines
- processes for access control to output devices
- mechanisms for supporting or implementing access control for output devices
Source NIST SP 800-53 controls
These controls are referenced by the official SP 800-171 Rev. 3 OSCAL record. Open the corresponding control pages for complete control text, enhancements, D3FEND mappings, and related learning.
Authoritative sources
- NIST SP 800-171 Revision 3 official publication ↗
- NIST SP 800-171A Revision 3 official publication ↗
- NIST OSCAL Content release used for this import ↗
Bare Metal Cyber is an independent educational publisher and is not affiliated with or endorsed by NIST. The official publications, the responsible federal agency, and the governing contract or agreement determine applicability, tailoring, assessment depth, and required implementation.