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MI-AUTH-01 - Boundary Protection Function

Principle

The mission should establish a mediated access mechanism that prevents unauthorized access to critical subsystems in the space segment.

Rationale

Cyber actors can exploit the ground system and use the ground segment to maliciously interact with the space vehicle. The boundary protection may be logical or physical. Functionality provides the following benefits:

  • Blocks unintended (incoming/outgoing) traffic
  • Enables generation and maintenance of Security Logs
  • Prevents devices from polling other network devices
  • Prevents devices from polling the network for other devices
  • Prevents bridging of networks
Effective boundary protection should/would include confidentiality protection using encryption (as defined by NASA STD 1006) in addition to some form of authentication (e.g., Galois/Counter Mode GCM). This boundary protection also needs to include protection on the space vehicle side where it protects itself from the ground being used as an attack vector. The inherent trust between the ground and space vehicle needs addressed where the space vehicle can protect itself from the ground in the event the ground has been compromised. Each mission should identify/define their most critical subsystems. Critical subsystems or control interfaces should have mediated access between mission critical control interfaces, that could create mission ending failure/consequence through either physical or software means.

Related Countermeasures

ID Name Description NIST Rev 5
CM0052 Insider Threat Protection Insider threats represent a distinct and particularly difficult risk category for space mission security, as individuals with authorized access to mission systems, facilities, and commanding infrastructure can cause significant damage without needing to overcome the external access controls that defend against outside adversaries. An insider threat program establishes the organizational, procedural, and technical controls necessary to deter, detect, and respond to malicious or negligent actions by personnel with legitimate access, including attempts by insiders to masquerade as other authorized individuals to access commanding functions or sensitive mission infrastructure under a false identity. The program must address both the technical controls that limit what any individual can do with their authorized access and the procedural and behavioral controls that create accountability, reduce opportunity, and enable early detection of concerning patterns. Effective insider threat protection requires integration across personnel security, access management, monitoring, and incident response functions, treating the insider threat as an ongoing operational risk to be managed continuously rather than a problem solved by initial personnel vetting alone. AC-14 AC-3(11) AC-3(13) AC-3(15) AC-6 AT-2 AT-2(2) AT-2(4) AT-2(5) AT-2(6) AU-10 AU-12 AU-13 AU-6 AU-7 CA-7 CP-2 IA-12 IA-12(1) IA-12(2) IA-12(3) IA-12(4) IA-12(5) IA-12(6) IA-4 IR-2(3) IR-4 IR-4(6) IR-4(7) MA-7 MP-7 PE-2 PL-8 PL-8(1) PM-12 PM-14 PS-3 PS-4 PS-5 PS-8 RA-10 SA-3 SA-8 SC-38 SC-7 SI-4 SR-11(2)
CM0054 Two-Person Rule The two-person rule (TPR) requires that all access to and actions within systems possessing command-level authority over the spacecraft be conducted in the continuous presence of two separately authorized individuals, neither of whom alone can complete the access or action. This control reduces the opportunity for unauthorized, coerced, erroneous, or malicious commanding by requiring two independently authorized individuals to participate in the protected access or action. Its effectiveness depends on individual attribution, independent review, resistance to credential sharing or account misuse, and protection against collusion or bypass of the enforcement mechanism. The TPR requires two distinct, appropriately authorized individuals to participate in the same protected access or action. Participation may be physically co-located, remotely performed through authenticated technical controls, or implemented through a combination of physical and logical mechanisms, as defined by mission policy. The second individual must independently review and approve the specific access or action before it is completed. Under CM0054, the two-person rule applies to access and actions involving systems with command-level access to the spacecraft to include reprograming the flight computer/flight software. If the mission tailors the rule to selected commanding functions, the retained scope, excluded access and actions, compensating controls, and associated risk acceptance must be explicitly documented and approved. AC-14 AC-3(13) AC-3(15) AC-3(2) AU-9(5) CP-2 IA-12 IA-12(1) IA-12(2) IA-12(3) IA-12(4) IA-12(5) IA-12(6) PE-3 SA-8(15)
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)
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)
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)
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)
CM0003 TEMPEST / EMSEC TEMPEST controls (i.e., emissions security (EMSEC)) protect spacecraft system components, internal data communications, and communication buses against side-channel and proximity-based attacks that exploit unintended electromagnetic, electrical, or acoustic emanations. Critical components must be enclosed within appropriate casings or shielding structures that attenuate unintended emissions to levels that deny adversaries the ability to reconstruct processed data or infer system state from externally observable signals. Shielding must extend to internal buses and data pathways, not only to individual processing elements, as inter-component communications represent a significant and often overlooked emanations surface. The physical enclosure strategy must be integrated with the broader system architecture so that shielding effectiveness is not degraded by penetrations, connectors, or cable routing that create unintended emissions paths. During sustainment & maintenance, Spacecraft TEMPEST and EMSEC protections are primarily established during design, fabrication, and integration, but sustainment remains applicable through configuration control, review of deployment-state or hardware changes, preservation of qualification evidence, assessment of relevant anomalies, and evaluation of refurbishment, replacement, or follow-on production changes. The guidance below addresses these spacecraft considerations as well as applicable ground-segment maintenance activities. PE-19 PE-19(1) PE-21 SC-8(3)
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)
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)
CM0005 Ground-based Countermeasures Ground-based countermeasures protect the terrestrial capabilities that develop, launch, command, monitor, operate, secure, and sustain space missions. These capabilities may be distributed across mission-owned systems, contractor environments, external partners, and commercial service providers. Because ground segment architectures and responsibilities vary, cybersecurity protections should be selected through threat-informed analysis of the mission functions being performed rather than through indiscriminate application of a single control set. The SPARTA Ground Segment Cyber Defenses guidance provides an interactive functional decomposition that maps ground segment function groups to applicable Defense-in-Depth sub-layers and countermeasure targets. The supporting report, VTR-2026-00702 Rev A, Ground Segment Cyber Defenses and Risk-Based Tiering, provides the methodology, definitions, and risk-tier rationale. The accompanying Ground Segment Cyber Defenses Excel Workbook consolidates the function mappings and Baseline and Enhanced countermeasure guidance into a resource that can be tailored to a specific mission architecture. SPARTA Ground Segment Cyber Defenses guidance
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)
CM0035 Protect Authenticators Authenticators and associated authenticator material, including passwords, secret and private keys, tokens, biometric templates, shared secrets, certificates, and trust-store entries, must be protected against unauthorized modification and, where the material is confidential, unauthorized disclosure throughout their lifecycle. Disclosure of secret authenticator material may enable adversaries to impersonate legitimate users or systems. Unauthorized modification of authenticators, certificates, or trust information can deny access to legitimate entities, substitute adversary-controlled credentials, or corrupt the trust basis of mission authentication mechanisms. Protection must apply to authenticators at rest, in transit, and in use, and must extend to all forms and storage locations, including credential databases, configuration files, embedded device credentials, hardware security tokens, and cryptographic key stores. Authenticator protection is a prerequisite for the effectiveness of any authentication-based access control; an authentication system whose authenticators are unprotected provides no meaningful security regardless of the strength of the underlying authentication protocol. AC-17(6) AC-3(11) CM-3(6) IA-4(9) IA-5 IA-5(6) PL-8 PL-8(1) SA-3 SA-4(5) SA-8 SA-8(13) SA-8(19) SC-16 SC-16(1) SC-8(1)
CM0053 Physical Security Controls Physical security controls form the outermost defensive layer protecting systems that can command the spacecraft, limiting access to commanding infrastructure to personnel who are both identity-verified and specifically authorized to be in those environments. Unauthorized physical access may enable theft, tampering, connection to exposed interfaces, use of unattended sessions, or attempts to extract or alter protected information. Physical security must therefore complement authentication, encryption, session management, tamper protection, and other technical controls rather than assume those controls will remain sufficient without protection of the underlying equipment. Physical security measures for commanding facilities and infrastructure must use layered controls selected according to the facility threat environment, system criticality, site characteristics, and consequence of unauthorized access. Controls may include perimeter barriers, controlled entry points, interior protected areas, identity and authorization verification, locks, intrusion detection, surveillance, and security personnel. Access to the facility must not, by itself, authorize physical access to commanding systems. Physical security controls must be commensurate with the sensitivity and criticality of the commanding functions they protect, with the most sensitive commanding capabilities requiring the most stringent physical access restrictions. AC-14 CA-3(6) CA-8 CA-8(1) CA-8(3) PE-2 PE-2(1) PE-2(3) PE-3 PE-3(1) PE-3(2) PE-3(3) PE-3(5) PE-3(7) SA-3 SA-8 SC-12(6) SC-51 SC-8(5) SR-11(2)
CM0070 Alternate Communications Paths Establishing alternate communications paths for spacecraft and ground system operations reduces the likelihood that a single adversarial event, physical disruption, or technical failure will deny all mission communications. Reliance on a single communications pathway creates a single point of failure that adversaries can exploit through jamming, denial of service against ground infrastructure, physical disruption of a ground station, or compromise of network connectivity, any of which could result in complete loss of commanding and telemetry capability. Alternate paths must be assessed end to end for shared failure modes and operational dependencies. Differences in frequency, ground station, relay service, or network provider provide meaningful resilience only when the paths do not remain dependent on the same critical spacecraft, ground, management, or service infrastructure. The selection and configuration of alternate paths must be governed by the mission's concept of operations (CONOPS), which defines the conditions under which each path is used, the priority and switchover procedures between paths, and the minimum communications capability that must be maintained to satisfy mission safety and operational continuity requirements. AC-17 CP-2 CP-4(2) CP-8(3) PL-8 PL-8(1) SC-47
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)
CM0067 Smart Contracts Smart contracts provide an automated, consensus-based enforcement mechanism for security protocols governing data exchange across a spacecraft bus, particularly in hosted payload architectures where multiple independently operated payloads or subsystems share common infrastructure. By encoding security rules as deterministic contract logic, participating validator nodes can evaluate authenticated observations of bus activity and reach consensus on whether a defined violation occurred. A trusted bus controller, gateway, or access-control mechanism must then enforce any approved restriction because the smart contract itself cannot directly observe or block physical bus traffic. This approach is directly applicable to scenarios where a hosted payload is compromised or behaves maliciously, as the smart contract framework can detect the violation, achieve consensus among the remaining bus participants, and enforce exclusion of the offending payload before the attack propagates to other bus components or the host spacecraft. The consensus mechanism should prevent a single participating node from causing payload exclusion when the approved quorum and membership rules require agreement from multiple independent validators. Its effectiveness depends on the validator architecture, quorum threshold, communication assumptions, and number of compromised or unavailable validators. Smart contract-based enforcement is particularly valuable in multi-tenant spacecraft architectures where payload operators are organizationally distinct from the spacecraft bus operator and cannot be governed through a single chain of administrative control. IA-9 SI-4 SI-4(2)
CM0065 OSAM Dual Authorization Before a cooperative OSAM engagement enters a protected proximity, capture, docking, mating, or servicing phase, the servicing spacecraft must be authenticated and the specific engagement authorized by both the serviced asset’s mission control authority and, where technically capable, the serviced asset itself. Authentication establishes the identity of the servicer, while dual authorization requires two independent approval decisions for the proposed activity. The approvals may be sequential rather than simultaneous but must both remain valid and be bound to the same servicer, client, service scope, mission phase, interfaces, operational constraints, and validity period. Failure to obtain or maintain authorization must cause the serviced asset to withhold cooperation and interface enablement and must invoke the approved hold, retreat, or abort response. These controls reduce the risk of unauthorized servicing but cannot physically prevent a hostile or non-cooperative spacecraft from approaching the asset. CA-3(6) IA-2(1) IA-2(2) IA-2(6)
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)