Security requirement
- a.Authorize internal connections of [Organization-defined: system components or classes of components] to the system.
- b.Document, for each internal connection, the interface characteristics, security requirements, and the nature of the information communicated.
- c.Terminate internal system connections after [Organization-defined: conditions].
- d.Review [Organization-defined: frequency] the continued need for each internal connection.
Discussion
Internal system connections are connections between organizational systems and separate constituent system components (i.e., connections between components that are part of the same system), including components that are used for system development. Intra-system connections include connections with mobile devices, notebook and desktop computers, tablets, printers, copiers, facsimile machines, scanners, sensors, and servers. Organizations can authorize internal connections for a class of system components with common characteristics and/or configurations, including printers, scanners, and copiers with a specified processing, transmission, and storage capability or smart phones and tablets with a specific baseline configuration. The continued need for an internal system connection is reviewed from the perspective of whether it provides support for organizational missions or business functions. This requirement is sourced to a control tailored out of the SP 800-53B .13 moderate baseline in SP 800-171.
Tailoring decisions required
Resolve these values through the governing organization’s approved tailoring and risk-management process before declaring the requirement implemented.
Protection strategies supported
These classifications are carried from the official SP 800-172 OSCAL record and help explain the enhanced requirement’s defensive purpose.
Implementation perspective
Treat Internal System Connections as an enhanced CUI protection outcome for elevated threat conditions that must be reflected in the system boundary, documented implementation, operational behavior, and assessment evidence. Pay particular attention to assessment planning, evidence quality, remediation, continuous monitoring, and system security plan accuracy.
- Confirm the federal agency selected this enhanced requirement for the critical program or high-value asset and identify the CUI system components, services, users, and external connections in scope.
- 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 critical-program or high-value-asset CUI, data flows, users, and services are protected by this enhanced 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
- assessment plans and reports
- plans of action and milestones
- system security plans
- continuous monitoring results
Common failure patterns
- requirement status based only on owner assertion
- findings closed without evidence
- scope missing inherited services
- monitoring data disconnected from risk decisions
Assessment objectives and methods
Assessment objectives (6)
- a.
internal connections of [Organization-defined: system components or classes of components] to the system are authorized.
- b.
for each internal connection, the interface characteristics are documented.
- b.
for each internal connection, the security requirements are documented.
- b.
for each internal connection, the nature of the information communicated is documented.
- c.
internal system connections are terminated after [Organization-defined: conditions].
- d.
the continued need for each internal connection is reviewed [Organization-defined: frequency].
Examine
- Assessment and monitoring policy
- access control policy
- procedures addressing system connections
- system and communications protection policy
- system design documentation
- system audit records
- list of components or classes of components authorized as internal system connections
- system security plan
- system configuration settings and associated documentation
- assessment report
- other relevant documents or records
Interview
- Personnel with responsibilities for developing, implementing, or authorizing internal system connections
- personnel with information security and responsibilities
Test
- Mechanisms supporting internal system connections
Source NIST SP 800-53 controls
These controls are referenced by the official SP 800-172 Rev. 3 OSCAL record. Open the corresponding control pages for complete control text, enhancements, D3FEND mappings, and related learning.
Authoritative sources
- NIST SP 800-172 Revision 3 official publication ↗
- NIST SP 800-172A 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.