Control statement
Control physical access to [Organization-defined: system distribution and transmission lines] within organizational facilities using [Organization-defined: security controls].
Discussion
Security controls applied to system distribution and transmission lines prevent accidental damage, disruption, and physical tampering. Such controls may also be necessary to prevent eavesdropping or modification of unencrypted transmissions. Security controls used to control physical access to system distribution and transmission lines include disconnected or locked spare jacks, locked wiring closets, protection of cabling by conduit or cable trays, and wiretapping sensors.
Organization-defined parameters
These values must be resolved through the organization’s tailoring and governance process. Bracketed parameter references in the control text identify where a decision is required.
From control text to operational evidence
Use Access Control for Transmission as a testable risk decision. Translate the official statement into accountable people, repeatable processes, configured technology, and evidence that demonstrates the outcome over time. In this family, pay particular attention to physical access, facility protection, environmental safeguards, and visitor accountability.
Implementation workflow
- Define the control boundary, responsible owner, inherited portions, and systems or processes in scope.
- Resolve each organization-defined parameter before declaring the control implemented.
- Document how the implementation satisfies every clause of the official control statement.
- Collect evidence as a normal byproduct of operation rather than only before an assessment.
- Review exceptions, changes, and monitoring results on a risk-based cadence.
Evidence examples
- badge and visitor logs
- physical access reviews
- facility diagrams and sensor records
- environmental and power test results
Common failure patterns
- logical security assumptions invalidated by physical access
- tailgating and visitor exceptions normalized
- critical infrastructure not included in access reviews
- environmental alarms not integrated into response
Questions practitioners should ask
- What risk decision is this control intended to support in this system?
- Which parts are implemented locally, inherited, shared, or not applicable—and what evidence supports that decision?
- Do the documented narrative, deployed configuration, operating process, and collected evidence agree?
- What event or threshold requires the implementation to be reviewed or changed?
Assessment objectives and methods
Show the assessment objective
physical access to [Organization-defined: system distribution and transmission lines] within organizational facilities is controlled using [Organization-defined: security controls].
Examine
- Physical and environmental protection policy
- procedures addressing 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
- system security plan
- other relevant documents or records
Interview
- Organizational personnel with physical access control responsibilities
- organizational personnel with information security responsibilities
Test
- Organizational processes for access control to distribution and transmission lines
- mechanisms/security safeguards supporting and/or implementing access control to distribution and transmission lines
Related controls
These relationships come from the official OSCAL catalog. They indicate useful dependencies or context, not automatic inheritance or equivalence.
Related NIST SP 800-171 requirements
These Rev. 3 requirements cite this base control or one of its enhancements as a source. The relationship does not by itself determine contractual applicability or complete implementation.
Authoritative sources
Bare Metal Cyber is an independent educational publisher and is not affiliated with or endorsed by NIST. Official control requirements and interpretations remain with NIST and the responsible authorizing organization.