The adversary re-sends previously valid commands or procedures to cause the spacecraft to transmit data again, then captures the resulting downlink. Typical targets are recorder playbacks, payload product dumps, housekeeping snapshots, or file directory listings. By aligning replays with geometry (e.g., when the satellite is in view of actor-controlled apertures) and with acceptance conditions (counters, timetags, mode), the attacker induces legitimate transmissions that appear routine to operators. Variants include selectively replaying index ranges to fetch only high-value intervals, reissuing subscription/telemetry-rate changes to increase data volume, or queueing playbacks that fire during later passes when interception is feasible.
| ID | Name | Tiering | Description | NIST Rev5 | ISO 27001 | Onboard SV | Ground | |
| CM0002 | COMSEC | Communications security (COMSEC) denies unauthorized parties access to information derived from telecommunications while ensuring the authenticity of those communications. COMSEC is commonly defined as a broad discipline that may encompass cryptographic security, transmission security, emissions security, cryptographic key management, traffic-flow security, and physical security of COMSEC material. Within SPARTA, these areas are further broken down through separate countermeasures, including CM0029 | TRANSEC, CM0030 | Crypto Key Management, CM0003 | TEMPEST/EMSEC, and CM0073 | Traffic Flow Analysis Defense. CM0002 provides the overarching communications-security context and supports the coordinated application of these specialized countermeasures. All mission links, particularly telemetry, tracking, and commanding (TT&C) links, should employ communications-security protections appropriate to the sensitivity, criticality, operational environment, and threat exposure of the information being exchanged. These protections may include cryptographic protection, transmission security, emissions security, traffic-flow protection, secure key management, and physical protection of COMSEC material, as addressed by the applicable specialized countermeasures. Spacecraft should not provide an operational mode that permits required cryptographic protection or command authentication on TT&C links to be bypassed or disabled. Operational, maintenance, test, recovery, and contingency modes should be considered when evaluating whether communications-security protections can be unintentionally or improperly circumvented. Communication receivers and associated signal-processing or TRANSEC mechanisms should detect and, when mission-defined criteria are met, reject or otherwise safely handle transmissions exhibiting anomalous signal characteristics consistent with communications deception. Cryptographic mechanisms should authenticate and integrity-check received content but should not be treated as RF-deception detectors. | AC-17 AC-17(1) AC-17(10) AC-17(2) AC-18 AC-18(1) AC-2(11) AC-3(10) CA-3 IA-4(9) IA-5 IA-5(7) IA-7 PL-8 PL-8(1) SA-8(18) SA-8(19) SA-9(6) SC-10 SC-12 SC-12(1) SC-12(2) SC-12(3) SC-12(6) SC-13 SC-16(3) SC-28(1) SC-28(3) SC-7 SC-7(10) SC-7(11) SC-7(18) SC-7(5) SC-8(1) SC-8(3) SI-10 SI-10(3) SI-10(5) SI-10(6) SI-19(4) SI-3(8) | A.5.14 A.6.7 A.8.1 A.8.16 A.5.14 A.8.1 A.8.20 A.5.14 A.8.21 A.5.16 A.5.17 A.5.8 A.5.14 A.8.16 A.8.20 A.8.22 A.8.23 A.8.26 A.8.12 A.5.33 A.8.20 A.8.24 A.8.24 A.8.26 A.5.31 A.5.33 A.8.11 | ||||
| CM0031 | Authentication | All command-bearing sessions, frames, or messages involving spacecraft command links, crosslinks, or relay services shall provide cryptographic authentication of the command origin and integrity verification before commands are accepted. Mutual or bidirectional authentication shall be required where both endpoints must authenticate one another and the link and protocol architecture support that exchange. Acquisition requirements should mandate cryptographically based, bidirectional authentication for all command sessions across external links, including ground-to-spacecraft uplinks, spacecraft-to-spacecraft crosslinks, and any relay or intermediary ground station connections, with authentication required aBidirectional authentication enables both communicating entities to verify each other’s identity and helps prevent impersonation. Authentication establishes identity but does not by itself authorize a command, protect mission-data confidentiality, or prevent session hijacking. Command acceptance must also enforce authorization, and authenticated sessions or security associations must maintain integrity and replay resistance so that subsequent traffic remains bound to the authenticated entities. Beyond external links, authentication is strongly recommended for spacecraft internal bus communications and onboard inter-component connections, as an adversary with access to internal interfaces, whether through a compromised component or a physical access event, should face the same authentication barrier as an external adversary attempting to inject commands from outside the spacecraft. | AC-14 AC-17 AC-17(10) AC-17(2) AC-18 AC-18(1) IA-2 IA-3(1) IA-4 IA-4(9) IA-7 IA-9 PL-8 PL-8(1) SA-3 SA-4(5) SA-8 SA-8(15) SA-8(9) SC-16 SC-16(1) SC-16(2) SC-32(1) SC-7(11) SC-8(1) SI-14(3) SI-7(6) | A.5.14 A.6.7 A.8.1 A.5.14 A.8.1 A.8.20 A.5.16 A.5.16 A.5.8 A.5.2 A.5.8 A.8.25 A.8.31 A.8.27 A.8.28 A.5.33 | ||||
| CM0033 | Relay Protection | Replay attacks capture and later retransmit previously valid authentication messages, frames, credentials, or tokens. Relay attacks forward an authentication exchange in real time between legitimate endpoints, causing an endpoint to authenticate a connection or action that the adversary is relaying without requiring compromise of the underlying cryptographic keys. Relay- and replay-resistant authentication mechanisms must be implemented when establishing remote connections or security associations with the spacecraft and for authenticated communications on spacecraft internal buses. The protections must prevent previously accepted authentication material or authenticated traffic from being reused outside its authorized context. Replay resistance should use freshness and anti-reuse mechanisms such as nonces, sequence numbers, timestamps where operationally suitable, and managed anti-replay windows. Relay resistance additionally requires authentication to be cryptographically bound to the intended endpoints, security association, session or channel context, and authenticated action. Challenge-response authentication provides replay resistance when fresh challenges are used but does not, by itself, prevent an adversary from relaying the challenge and response between legitimate endpoints. These protections must be applied at both external interface boundaries, including ground-to-spacecraft command links and crosslinks, and internal spacecraft bus connections where component-to-component authentication is implemented. | AC-17(10) IA-2(8) IA-3 IA-3(1) IA-4 IA-7 SC-13 SC-16(1) SC-23 SC-23(1) SC-23(3) SC-7 SC-7(11) SC-7(18) SI-10 SI-10(5) SI-10(6) SI-3(8) | A.5.16 A.5.14 A.8.16 A.8.20 A.8.22 A.8.23 A.8.26 A.8.24 A.8.26 A.5.31 | ||||
| CM0036 | 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. | AC-12 AC-12(2) SC-10 SI-14(3) SI-4(7) | A.8.20 | ||||
| CM0055 | Secure Command Mode(s) | Secure command modes provide additional layers of restriction on spacecraft command acceptance beyond standard authentication and encryption, constraining when, where, and under what operational conditions the spacecraft will process commands. These supplemental controls reduce the window of opportunity for unauthorized commanding by limiting command receptivity to defined parameters that an adversary would need to satisfy simultaneously with authentication requirements, substantially increasing the difficulty of a successful command injection attack. Specific implementations include geographic restriction, in which the spacecraft accepts commands only when in contact with designated ground station locations; operational mode restrictions, in which special flight software (FSW) modes must be active before certain command categories are accepted; and temporal controls, in which the spacecraft enforces time-bounded windows during which commands are valid. These mechanisms complement command authentication, integrity protection, anti-replay controls, and authorization and do not replace them. Encryption should also be applied where command confidentiality is required. Secure command modes may combine geographic, temporal, operational-state, source, or other mission-defined conditions according to the active command policy. Secure command modes helps create a multi-dimensional command acceptance policy that an adversary must defeat in its entirety to achieve unauthorized command execution. | AC-17(1) AC-17(10) AC-2(11) AC-2(12) AC-3 AC-3(2) AC-3(3) AC-3(4) AC-3(8) CA-3(7) IA-10 PL-8 PL-8(1) SA-3 SA-8 SC-7 SI-3(8) | A.8.16 A.5.15 A.5.33 A.8.3 A.8.4 A.8.18 A.8.20 A.8.2 A.8.16 A.5.8 A.5.2 A.5.8 A.8.25 A.8.31 A.8.27 A.8.28 A.5.14 A.8.16 A.8.20 A.8.22 A.8.23 A.8.26 | ||||
| CM0034 | Monitor Critical Telemetry Points | Monitoring defined spacecraft telemetry points provides a key source of evidence for detecting adversary activity against on-orbit systems, where observability is largely limited to the events and conditions the spacecraft can sense, record, and report. Monitored telemetry must include both accepted and rejected commands, command mode transitions, command counters, and other indicators of commanding activity, enabling detection of unauthorized command attempts that fail authentication as well as anomalous patterns in legitimate command traffic. Monitoring scope should include RF and link-quality indicators that support detection and triage of interference or suspected jamming. These indicators should be correlated with expected link conditions and other available evidence before hostile activity is concluded. Security-relevant telemetry should be integrated and time-correlated with ground-based defensive cyber operations infrastructure, including security information and event management (SIEM) and audit platforms, to provide unified space-system cybersecurity situational awareness. The resulting view should correlate spacecraft observations with relevant ground-system security events while accounting for telemetry latency, contact availability, and other observability limitations. | AC-17(1) AU-3(1) CA-7(6) IR-4(14) PL-8 PL-8(1) SA-8(13) SC-16 SC-16(1) SC-7 SI-3(8) SI-4(7) | A.8.16 A.5.8 A.5.14 A.8.16 A.8.20 A.8.22 A.8.23 A.8.26 | ||||
| CM0032 | On-board Intrusion Detection & Prevention | An on-board intrusion detection and prevention system (IDS/IPS) monitors mission-critical spacecraft components and systems, generates and stores audit records, and supports mission-approved responses to detected threats. Depending on the mission architecture, threat, and availability of ground support, responses may be autonomous, ground-directed, or a combination of both. The system should address both known attack patterns and previously unseen anomalous behavior through complementary signature-based and behavior- or anomaly-based detection methods. Machine learning or adaptive technologies may be used when their performance, resource consumption, and failure behavior have been validated for the mission environment. Detection and response coverage should address applicable adversary activities across the attack lifecycle, including initial access, execution, persistence, defense evasion, and exfiltration. The on-board IDS/IPS must be integrated with the spacecraft's traditional fault management system to provide a unified approach to anomaly response, ensuring that cyber-triggered responses are compatible with fault management logic and do not produce unintended effects or fratricide against the spacecraft's own systems; countermeasures that are incompatible with fault management are considered unsafe and must not be executed autonomously. The response hierarchy must prioritize vehicle safety and continued mission operations. Advanced containment or deception responses may be considered when they can be executed without unacceptable mission risk. The system should preserve evidence that supports post-event analysis, threat characterization, and potential attribution by authorized ground support. | AU-14 AU-2 AU-3 AU-3(1) AU-4 AU-4(1) AU-5 AU-5(2) AU-5(5) AU-6(1) AU-6(4) AU-8 AU-9 AU-9(2) AU-9(3) CA-7(6) CM-11(3) CP-10 CP-10(4) IR-4 IR-4(11) IR-4(12) IR-4(14) IR-4(5) IR-5 IR-5(1) PL-8 PL-8(1) RA-10 RA-3(4) SA-8(21) SA-8(22) SA-8(23) SC-16(2) SC-32(1) SC-5 SC-5(3) SC-7(10) SC-7(9) SI-10(6) SI-16 SI-17 SI-3 SI-3(10) SI-3(8) SI-4 SI-4(1) SI-4(10) SI-4(11) SI-4(13) SI-4(16) SI-4(17) SI-4(2) SI-4(23) SI-4(24) SI-4(25) SI-4(4) SI-4(5) SI-4(7) SI-6 SI-7(17) SI-7(8) | A.8.15 A.8.15 A.8.6 A.8.17 A.5.33 A.8.15 A.8.15 A.5.29 A.5.25 A.5.26 A.5.27 A.5.8 A.5.7 A.8.12 A.8.7 A.8.16 A.8.16 A.8.16 A.8.16 | ||||
| CM0029 | TRANSEC | Transmission security (TRANSEC) is the component of communications security (COMSEC) concerned with protecting the characteristics of the transmission itself, as distinct from protecting the content of the information being communicated. TRANSEC controls reduce the likelihood, effectiveness, or operational impact of transmission interception, signal disruption, communications deception, and exploitation of transmission characteristics within the defined threat model. Applicable TRANSEC techniques include jam-resistant waveforms that increase resistance to jamming and communications deception, spread spectrum and frequency hopping techniques that reduce signal predictability and improve resistance to interception and disruption, low probability of intercept and low probability of detection (LPI/LPD) signal designs that reduce transmission observability, and transmission scheduling or pattern discipline that limits the intelligence value of traffic analysis. TRANSEC requirements should be applied to mission communication links according to link criticality (e.g., TT&C, crosslinks), threat exposure, and operational consequence. TRANSEC must be treated as a distinct layer of protection complementary to, but not a substitute for, cryptographic protection of information content. | AC-17 AC-18 AC-18(5) CA-3 CP-8 PL-8 PL-8(1) SA-8(19) SC-16 SC-16(1) SC-40 SC-40(1) SC-40(3) SC-40(4) SC-5 SC-8(1) SC-8(3) SC-8(4) | A.5.14 A.6.7 A.8.1 A.5.14 A.8.1 A.8.20 A.5.14 A.8.21 A.5.29 A.7.11 A.5.8 A.5.33 | ||||