CA-9: Internal System Connections
Control Family:
CSF v1.1 References:
CSF v2.0 References:
Threats Addressed:
Baselines:
- Low
- CA-9
- Moderate
- CA-9
- High
- CA-9
- Privacy
N/A
- OT Low (SP 800-82r3)
- CA-9
- OT Moderate (SP 800-82r3)
- CA-9
- OT High (SP 800-82r3)
- CA-9
Previous Version:
- NIST Special Publication 800-53 Revision 4:
- CA-9: Internal System Connections
Control Statement
- Authorize internal connections of [Assignment: organization-defined system components] to the system;
- Document, for each internal connection, the interface characteristics, security and privacy requirements, and the nature of the information communicated;
- Terminate internal system connections after [Assignment: organization-defined conditions] ; and
- Review [Assignment: organization-defined frequency] the continued need for each internal connection.
Supplemental Guidance
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 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. Instead of authorizing each internal system connection individually, 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.
OT Discussion
Organizations perform risk-benefit analysis to determine whether OT equipment should be connected to other internal system components and then document those connections. The AO fully understands the potential risks associated with approving individual connections or approving a class of components to be connected. For example, the AO may broadly approve the connection of any sensors limited to 4 to 20 milliamp (mA) communication, while other connection types (e.g., serial or Ethernet) require individual approval. Decisions to accept risk are documented.
Control Enhancements
CA-9(1): Compliance Checks
Baseline(s):
Perform security and privacy compliance checks on constituent system components prior to the establishment of the internal connection.