Many payloads maintain communications separate from the primary TT&C, direct downlinks to user terminals, customer networks, or experimenter VPNs. An adversary who implants code in the payload (or controls its gateway) can route host-bus data into these channels, embed content within payload products (e.g., steganographic fields in imagery/telemetry), or schedule covert file transfers alongside legitimate deliveries. Because these paths are expected to carry high-rate mission data and may bypass TT&C monitoring, they provide a discreet conduit to exfiltrate payload or broader spacecraft information without altering the primary command link’s profile.
| 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 | ||||
| CM0030 | Crypto Key Management | Effective cryptographic key management is a foundational requirement for all mission encryption and authentication functions; the security of cryptographic implementations is only as strong as the protection afforded to the keys those implementations rely upon. Key management must conform to recognized cryptographic guidance and address the full lifecycle applicable to each key type, including generation or establishment, distribution, storage, activation, use, replacement, deactivation or revocation, recovery where authorized, compromise response, and destruction. Only approved cryptographic algorithms, key generation methods, key distribution techniques, and authentication mechanisms may be used; the use of unapproved, deprecated, or custom cryptographic primitives is prohibited regardless of perceived functional adequacy. Encryption key handling must be performed outside of onboard software and protected through dedicated cryptographic mechanisms, preventing keys from being exposed through software vulnerabilities, memory inspection, or software-level debugging interfaces. Secret and private key material must not be retrievable in plaintext through telecommands, telemetry, diagnostic outputs, debugging interfaces, or other externally accessible mechanisms, regardless of the privilege level of the requesting entity. | CM-3(6) PL-8 PL-8(1) SA-3 SA-4(5) SA-8 SA-9(6) SC-12 SC-12(1) SC-12(2) SC-12(3) SC-12(6) SC-28(3) SC-8(1) | A.5.8 A.5.2 A.5.8 A.8.25 A.8.31 A.8.27 A.8.28 A.5.33 A.8.24 | ||||
| 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 | ||||
| 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 | ||||
| CM0039 | Least Privilege | The principle of least privilege requires that every process, user account, service, and system component be granted only the permissions and access rights necessary to perform its defined function, with no additional privileges retained beyond what the assigned task requires. Applied to spacecraft and ground systems, this means that processes executing on flight computers, operating system services, ground system applications, and inter-system communication handlers are each confined to the minimum privilege level needed for their specific function, preventing a compromised or malfunctioning component from leveraging excess permissions to affect other system resources or functions. Separate execution domains should be used where supported to reinforce least privilege and contain process failures or compromise. Process isolation does not replace explicit access controls, because authorized communication and shared resources may still cross execution-domain boundaries. Least privilege is a foundational design principle that reduces the consequence of any individual component compromise by limiting what an adversary can accomplish within that component's execution context. | AC-2 AC-3(13) AC-3(15) AC-4(2) AC-6 CA-3(6) CM-7 CM-7(5) CM-7(8) PL-8 PL-8(1) SA-17(7) SA-3 SA-4(9) SA-8 SA-8(13) SA-8(14) SA-8(15) SA-8(19) SA-8(3) SA-8(4) SA-8(9) SC-2(2) SC-32(1) SC-49 SC-50 SC-7(29) | A.5.16 A.5.18 A.8.2 A.5.15 A.8.2 A.8.18 A.8.19 A.8.19 A.5.8 A.5.2 A.5.8 A.8.25 A.8.31 A.8.27 A.8.28 | ||||
| CM0038 | Segmentation | Segmentation establishes physical or logical isolation boundaries between spacecraft system components and functional domains to limit the propagation of compromise, contain the consequences of a security failure, and enforce controlled information flow across the mission architecture. Mission-critical functions must be isolated from non-mission-critical functions through enforced partition boundaries that control access to and protect the integrity of the hardware, software, and firmware implementing those functions. Information flow between partitioned components or applications must be explicitly authorized by security policy; any flow not affirmatively permitted is denied by default. Boundary protections must be implemented to separate spacecraft bus, communications, and payload components, preventing a compromise in one domain from directly affecting the others. Information crossing the spacecraft boundary shall receive confidentiality protection where required by its classification, sensitivity, or mission risk. Command-bearing and other security-critical exchanges shall receive the mission-required authentication, integrity, authorization, and anti-replay protections regardless of whether confidentiality is required. These controls collectively implement a defense-in-depth architecture in which an adversary who gains a foothold in one partition faces enforced barriers before reaching mission-critical assets. | AC-4 AC-4(14) AC-4(2) AC-4(24) AC-4(26) AC-4(31) AC-4(32) AC-4(6) AC-6 CA-3 CA-3(7) PL-8 PL-8(1) SA-3 SA-8 SA-8(13) SA-8(15) SA-8(18) SA-8(3) SA-8(4) SA-8(9) SC-16(3) SC-2(2) SC-3 SC-3(4) SC-32 SC-32(1) SC-39 SC-4 SC-49 SC-50 SC-6 SC-7(20) SC-7(21) SC-7(29) SC-7(5) SI-17 SI-4(7) | A.5.14 A.8.22 A.8.23 A.5.15 A.8.2 A.8.18 A.5.14 A.8.21 A.5.8 A.5.2 A.5.8 A.8.25 A.8.31 A.8.27 A.8.28 | ||||
| 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 | ||||