Session Termination

Where session-oriented communications are used between ground systems and spacecraft, between ground system components, or across internal spacecraft interfaces, the associated connection or session must be terminated upon completion or after a period of inactivity exceeding a threshold defined in the mission’s concept of operations (CONOPS). Failure to terminate idle or completed sessions leaves authenticated connections open and exploitable, providing adversaries with an opportunity to inject commands or data into an existing authenticated session without needing to complete the authentication process independently. Inactivity timeout thresholds must be established through the CONOPS process rather than set arbitrarily, balancing the security benefit of rapid session termination against the operational consequences of terminating a session that an operator or automated process may legitimately require across a contact gap or processing delay. Session termination must invalidate the associated session identifiers, authorization state, and cryptographic session state so that the terminated session cannot be reused. Where secure session resumption is operationally required, it must use a mission-approved, cryptographically protected mechanism with defined validity limits and must not permit reuse of expired, revoked, or invalidated session state.

Sources

  • CCSDS 714.0-B-2 — Space Communications Protocol Specification (SCPS)—Transport Protocol
ID: CM0036
Tier: I
Onboard SV CM 
Created: 2022/10/19
Last Modified: 2026/08/06

Pre-Operations Government

Acquisition requirements should mandate automatic termination for applicable session-oriented communications after mission-defined conditions or periods of inactivity. Termination requirements should address ground-to-spacecraft command sessions, inter-ground-system connections, and administrative or diagnostic sessions based on their operational purpose and security risk. Requirements should specify that inactivity timeout values be defined in the mission CONOPS and documented as configuration parameters subject to government review and approval, rather than left to contractor or operator discretion. Contract language should require that termination invalidate the affected session and prevent its identifiers, tokens, or cryptographic state from being reused. Re-establishment must require a new authenticated session or an approved cryptographically protected resumption process that validates the continuing authority of both endpoints. Verification should confirm that automatic termination occurs under the specified conditions, that invalidated session identifiers and cryptographic state cannot be reused, and that any approved session-resumption mechanism enforces its authentication, authorization, and validity requirements. Evaluation criteria should assess offerors' session management designs for completeness of state teardown and their proposed approach to coordinating CONOPS-defined timeout values across all session types.

Pre-Operations Developer/Supplier

Session management must be implemented as an explicit system function with defined termination behavior for every session type used across the mission architecture, including operator console sessions, automated ground system inter-process sessions, telemetry and commanding sessions, and any maintenance or diagnostic connections. Inactivity timeout values should be defined according to session type, operational purpose, exposure, and mission consequence. Planned contact gaps or intermittent connectivity should be addressed through the applicable security-association or session-management policy rather than treated as ordinary inactivity. Session termination must invalidate session identifiers, authorization tokens, and session cryptographic secrets and must securely clear sensitive state that is no longer required. Anti-replay counters, audit records, and other security state should be retained or advanced as required to prevent previously accepted traffic from becoming valid after termination or restart. The session termination implementation must be tested for normal completion, timeout-driven termination, abnormal connection loss, and attempted reuse of terminated session state. Testing should verify that sensitive session state is invalidated or cleared as required and that retained security state does not permit unauthorized session restoration or replay. CONOPS-derived timeout values should be implemented as configuration parameters rather than hardcoded constants, enabling adjustment through the configuration management process as operational experience refines the appropriate thresholds without requiring software changes.