Control statement
Restrict or prohibit field maintenance on [Organization-defined: systems or system components] to [Organization-defined: trusted maintenance facilities].
Discussion
Field maintenance is the type of maintenance conducted on a system or system component after the system or component has been deployed to a specific site (i.e., operational environment). In certain instances, field maintenance (i.e., local maintenance at the site) may not be executed with the same degree of rigor or with the same quality control checks as depot maintenance. For critical systems designated as such by the organization, it may be necessary to restrict or prohibit field maintenance at the local site and require that such maintenance be conducted in trusted facilities with additional controls.
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 Field Maintenance 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 controlled maintenance, trusted tools, authorized personnel, and monitored support access.
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
- maintenance schedules and tickets
- tool approval records
- remote maintenance session logs
- maintenance personnel authorization
Common failure patterns
- vendor access left enabled permanently
- unapproved diagnostic tools introduced
- maintenance bypasses normal change control
- remote sessions not monitored or terminated
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
field maintenance on [Organization-defined: systems or system components] are restricted or prohibited to [Organization-defined: trusted maintenance facilities].
Examine
- Maintenance policy
- procedures addressing field maintenance
- system design documentation
- system configuration settings and associated documentation
- maintenance records
- diagnostic records
- system security plan
- other relevant documents or records.
Interview
- Organizational personnel with system maintenance responsibilities
- organizational personnel with information security responsibilities
- system/network administrators
Test
- Organizational processes for managing field maintenance
- mechanisms implementing, supporting, and/or managing field maintenance
- mechanisms for strong authentication of field maintenance diagnostic sessions
- mechanisms for terminating field maintenance sessions and network connections
Related controls
These relationships come from the official OSCAL catalog. They indicate useful dependencies or context, not automatic inheritance or equivalence.
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.