CA-3(7) - Information Exchange | Transitive Information Exchanges

(a) Identify transitive (downstream) information exchanges with other systems through the systems identified in CA-3a; and (b) Take measures to ensure that transitive (downstream) information exchanges cease when the controls on identified transitive (downstream) systems cannot be verified or validated.


ID: CA-3(7)
Enhancement of : CA-3

Space Segment Guidance

Transitive information exchanges on spacecraft are common when data flows through multiple relay points or hosted payloads before reaching its final destination. Such exchanges can introduce significant risk if an upstream node is compromised, allowing malicious code or corrupted data to pass “transitively” into critical systems. A robust defense-in-depth strategy is advisable: incorporate cryptographic integrity checks at each hop to detect unauthorized modifications and implement strict domain-based routing or forwarding policies that constrain which subsystems can relay data to one another. Additionally, advanced platforms can embed data labeling or tagging mechanisms so that each payload or bus subsystem verifies label integrity before accepting or forwarding content. This layered approach ensures that downstream components can still enforce local checks even if one exchange point is compromised. By rigorously identifying trust boundaries and verifying each stage of data flow, spacecraft operators significantly reduce the risk of chain-reaction compromises across multiple subsystems.