Shared Resource Leakage

Shared system resources (e.g., processor registers, main memory, secondary storage, cache) may retain residual data or security-relevant state after a process releases them for reuse. If a subsequent process can access that residual information, it may obtain data from the prior process, including sensitive information or encrypted representations of information that were not intended to cross process or partition boundaries. This countermeasure requires that shared resources be sanitized, zeroed, or otherwise cleared of prior process data before being allocated to a new process, ensuring that information transfer between processes occurs only through explicitly authorized channels. The protection must apply to encrypted representations as well as plaintext because encrypted data remains information belonging to the prior process and must not be transferred to another process solely because its contents are not immediately readable. This is particularly significant in space system environments where multiple processes of varying criticality and trust levels may share the same hardware resources.

ID: CM0040

Tier: I

Onboard SV CM

Created: 2022/10/19

Last Modified: 2026/08/06

Pre-Operations Government

Acquisition requirements should explicitly address shared-resource leakage, requiring that a process reusing a shared resource cannot access information retained from its prior use. Clearing or zeroization should be required for resources that retain directly accessible data, while other resources should use isolation, reinitialization, flushing, partitioning, or equivalent mechanisms appropriate to the resource. Protection should be enforced by trusted system resource-management mechanisms rather than relying solely on individual processes. Requirements should specify that shared-resource protections apply to both plaintext and encrypted information retained from prior use, and that the implementation be verified through testing that confirms no residual data from a prior process is accessible to a subsequent process following resource reallocation. Contract language should require that the resource management architecture be documented in the system security design, identifying each category of shared resource, the clearing mechanism applied to each, and the assurance argument for why the mechanism is sufficient. Evaluation criteria should assess offerors' proposed operating environment, their demonstrated experience with resource sanitization in safety- and security-critical embedded systems, and the adequacy of their proposed verification approach for shared resource leakage prevention. Flow-down provisions should ensure that operating system and runtime environment providers whose software manages shared resources implement clearing behaviors consistent with the program's requirements.

Pre-Operations Developer/Supplier

Shared-resource protections should be enforced by the trusted layer responsible for allocating and reassigning the resource, such as the operating system, runtime environment, hypervisor, firmware, or hardware resource controller. Application-level sanitization may supplement these controls but should not be the sole protection against leakage to another process. Memory allocation routines, register management, and storage block assignment functions should be configured or implemented to zero or overwrite the allocated region before returning it to the requesting process, ensuring that no prior content is accessible regardless of the allocation source or the trust level of the requesting process. In resource-constrained flight environments, the selected protection mechanism should balance leakage prevention with timing, performance, and resource constraints. Where clearing on every reuse is not operationally feasible, the design should use an alternative mechanism, such as dedicated allocation, partitioning, controlled reuse, or resource reinitialization, that still prevents a subsequent process from accessing information from the prior use. Residual-data clearing does not address every shared-resource side channel. Timing, contention, cache-state, queue-state, and other indirect leakage paths should be evaluated through the threat model and addressed through appropriate isolation, flushing, partitioning, or scheduling controls. Testing for shared resource leakage should include scenarios in which a process is allocated a resource immediately following a process that handled sensitive data, with verification that no residual sensitive data is accessible in the newly allocated resource.

Sustainment & Maintenance Government

Operational maintenance of shared resource leakage protection requires that software updates to operating system components, memory managers, and runtime environments be evaluated for their impact on shared-resource protection behaviors before deployment, as optimizations introduced in updated software versions may eliminate or reduce clearing operations in ways that reintroduce leakage vulnerabilities. Security regression testing for software updates that touch resource management components should include explicit shared resource leakage test cases, confirming that the update preserves the required clearing behavior across all covered resource categories. Shared-resource protection mechanisms should be validated through direct functional testing, configuration verification, and available mechanism-health indicators. Changes in processing overhead should not be relied upon as evidence that clearing or other leakage-prevention behavior is functioning correctly. Any operational anomaly that suggests a process has accessed data it should not have been able to access, including unexpected process behavior that could be explained by residual data from a prior process, should trigger an investigation that includes assessment of shared resource leakage as a possible cause.

Sustainment & Maintenance Developer/Supplier

Techniques Addressed by Countermeasure

ID		Name	Description
IA-0005		Rendezvous & Proximity Operations	Adversaries may execute a sequence of orbital maneuvers to co-orbit and approach a target closely enough for local sensing, signaling, or physical interaction. Proximity yields advantages that are difficult to achieve from Earth: high signal-to-noise for interception, narrowly targeted interference or spoofing, observation of attitude/thermal behavior, and, if interfaces exist, opportunities for mechanical mating. The approach typically unfolds through phasing, far-field rendezvous, relative navigation (e.g., vision, lidar, crosslink cues), and closed-loop final approach. At close distances, an attacker can monitor side channels, stimulate acquisition beacons, test crosslinks, or prepare for contact operations such as capture or docking. Contact itself is not the endpoint: mating and grappling expose data and power umbilicals, standardized payload ports, service and checkout connectors, and device programming interfaces that are unreachable by any other means.
	.02	Docked Vehicle / OSAM	Docking, berthing, or service capture during on-orbit servicing, assembly, and manufacturing (OSAM) creates a high-trust bridge between vehicles. Threat actors exploit this moment, either by pre-positioning code on a servicing vehicle or by manipulating ground updates to it, so that, once docked, lateral movement occurs across the mechanical/electrical interface. Interfaces may expose power and data umbilicals, standardized payload ports, or gateways into the target’s C&DH or payload networks (e.g., SpaceWire, Ethernet, 1553). Service tools that push firmware, load tables, transfer files, or share time/ephemeris become conduits for staged procedures or implants that execute under maintenance authority. Malware can be timed to activation triggers such as “link up,” “maintenance mode entered,” or specific device enumerations that only appear when docked. Because OSAM operations are scheduled and well-documented, the adversary can align preparation with published timelines, ensuring that the first point of execution coincides with the brief window when cross-vehicle trust is intentionally elevated.
	.03	Proximity Grappling	In this variant, the attacker employs a capture mechanism (robotic arm, grappling fixture, magnetic or mechanical coupler) to establish physical contact without full docking. Once grappled, covers can be manipulated, temporary umbilicals attached, or exposed test points engaged; if design provisions exist (service ports, checkout connectors, external debug pads), these become direct pathways to device programming interfaces (e.g., JTAG/SWD/UART), mass-storage access, or maintenance command sets. Grappling also enables precise attitude control relative to the target, allowing contact-based sensors to read buses inductively or capacitively, or to inject signals onto harness segments reachable from the exterior. Initial access arises when a maintenance or debug path, normally latent in flight, is electrically or logically completed by the grappled connection, allowing authentication-bypassing actions such as boot-mode strapping, image replacement, or scripted command ingress. The operation demands accurate geometry, approach constraints, and fixture knowledge, but yields a transient, high-privilege bridge tailored for short, decisive actions that leave minimal on-orbit RF signature.
IA-0006		Compromise Hosted Payload	Adversaries target hosted payloads as an alternate doorway into the host spacecraft. Hosted payloads often expose their own command sets, file services, and telemetry paths, sometimes via the host’s TT&C chain, sometimes through a parallel ground infrastructure under different operational control. Initial access arises when an attacker obtains the ability to issue payload commands, upload files, or alter memory/register state on the hosted unit. Because data and control must traverse an interface to the host bus (power, time, housekeeping, data routing, gateway processors), the payload–host boundary can also carry management functions: mode transitions, table loads, firmware updates, and cross-strapped links that appear only in maintenance or contingency modes. With knowledge of the interface specification and command dictionaries, a threat actor can activate rarely used modes, inject crafted data products, or trigger gateway behaviors that extend influence beyond the payload itself. In multi-tenant or commercial hosting arrangements, differences in keying, procedures, or scheduling between the payload operator and the bus operator provide additional opportunity for a first foothold that looks like routine payload commanding.
IA-0013		Compromise Host Spacecraft	The inverse of "IA-0006: Compromise Hosted Payload", this technique describes adversaries that are targeting a hosted payload, the host space vehicle (SV) can serve as an initial access vector to compromise the payload through vulnerabilities in the SV's onboard systems, communication interfaces, or software. If the SV's command and control systems are exploited, an attacker could gain unauthorized access to the vehicle's internal network. Once inside, the attacker may laterally move to the hosted payload, particularly if it shares data buses, processors, or communication links with the vehicle.
EX-0009		Exploit Code Flaws	The adversary executes actions on-board by abusing defects in software that runs on the vehicle, ranging from application logic in flight software to libraries, drivers, and supporting services. Outcomes range from arbitrary code execution and privilege escalation to silent logic manipulation (e.g., bypassing interlocks, suppressing alarms) that appears operationally plausible. The hallmark of this technique is that the attacker co-opts existing code paths, often rarely used ones, to run unintended behavior under nominal interfaces. These attacks may be extremely targeted and tailored to specific coding errors introduced as a result of poor coding practices or they may target known issues in the commercial software components.
	.02	Operating System	At the OS layer, the attacker targets primitives that schedule work and mediate hardware. Modern spacecraft, particularly small satellites, increasingly rely on Linux-based operating systems (e.g., Yocto-derived distributions) rather than traditional RTOSes, significantly expanding the applicable attack surface to include techniques documented in MITRE ATT&CK for Linux - <a href='https://attack.mitre.org/matrices/enterprise/linux/' class='internal-link' target='_blank'>https://attack.mitre.org/matrices/enterprise/linux/</a>. Maintenance builds may expose shells or management consoles; misconfigurations around these interfaces can provide paths to command interpreters or privileged syscalls. Linux-based flight systems inherit standard Unix/Linux vulnerabilities including kernel exploits, container escapes, privilege escalation via misconfigured sudo/capabilities, and exploitation of systemd or other init systems. Exploitation yields kernel-mode execution, arbitrary memory read/write, or control of scheduling and address spaces, letting the actor tamper with FSW processes, intercept command paths, or manipulate storage and bus drivers beneath application checks. Common Linux-specific vectors include exploiting unpatched kernel vulnerabilities, abusing misconfigurations in containerized environments, leveraging POSIX API weaknesses in flight applications, and targeting shared libraries or dynamic linkers to inject malicious code into flight processes. The technique leverages generic OS weaknesses adapted to the spacecraft's particular build, turning low-level control into mission-facing effects that appear to originate from legitimate processes. Because spacecraft Linux builds are often minimized, long-lived (limited patching), and may retain debug interfaces or permissive file permissions from ground testing, they present a unique risk profile combining embedded-system constraints with commodity OS attack techniques. Flight images frequently retain extraneous binaries and utilities (e.g., compilers, debuggers, network tools, package managers) intended for ground testing or development that are not removed before launch, providing adversaries with ready-made 'living off the land' capabilities for reconnaissance, lateral movement, and privilege escalation without needing to upload custom tooling.
LM-0001		Hosted Payload	The adversary pivots through the host–payload boundary to reach additional subsystems. Hosted payloads exchange power, time, housekeeping, and data with the bus via defined gateways (e.g., SpaceWire, 1553, Ethernet) and often support file services, table loads, and command dictionaries distinct from the host’s. A foothold on the payload can be used to inject traffic through the gateway processor, request privileged services (time/ephemeris distribution, firmware loads), or ride shared backplanes where payload traffic is bridged into C&DH networks. In some designs, payload processes execute on host compute or expose maintenance modes that temporarily widen access, creating paths from the payload into attitude, power, storage, or recorder resources. The movement is transitive: compromise a co-resident unit, then traverse the trusted interface that already exists for mission operations.
LM-0002		Exploit Lack of Bus Segregation	On flat architectures, where remote terminals, subsystems, and payloads share a common bus with minimal partitioning, any node that can transmit may influence many others. An attacker leverages this by forging message IDs or terminal addresses, replaying actuator/sensor frames, seizing or imitating bus-controller roles, or abusing gateway bridges that forward traffic between links (e.g., 1553↔SpaceWire/CAN). Because consumers often act on the latest valid-looking message, crafted traffic from one compromised device can reconfigure peers, toggle power domains, or write persistent parameters. Weak role enforcement and broadcast semantics allow privilege escalation from a peripheral to effective system-wide influence, turning the shared medium into a highway for further compromise.
LM-0004		Visiting Vehicle Interface(s)	Docking, berthing, or short-duration attach events create high-trust, high-bandwidth connections between vehicles. During these operations, automatic sequences verify latches, exchange status, synchronize time, and enable umbilicals that carry data and power; maintenance tools may also push firmware or tables across the interface. An attacker positioned on the visiting vehicle can exploit these handshakes and service channels to inject commands, transfer files, or access bus gateways on the host. Because many actions are expected “just after dock,” malicious traffic can ride the same procedures that commission the interface, allowing lateral movement from the visiting craft into the target spacecraft’s C&DH, payload, or support subsystems.
LM-0006		Launch Vehicle Interface	During integration and ascent, payloads and the launch vehicle exchange power, discrete lines, and data via umbilicals, separation avionics, and shared EGSE networks. Protections can be reduced or heterogeneous because timelines are tight and responsibilities cross organizations. An attacker positioned on either side (vehicle or payload) can use these commissioning links, health/status queries, time distribution, inhibit lines, separation commands, or telemetry gateways, to inject messages, transfer files, or alter configuration that propagates across the interface. Before fairing close and prior to separation, this brief but high-trust coupling provides a route to move from one platform to the other and to seed artifacts that persist after deployment.
	.01	Rideshare Payload	In shared launches, multiple independent payloads cohabit common infrastructure until separation. If isolation is incomplete (e.g., shared data buses, mispartitioned deployer controllers, common logging/telemetry collectors, or cross-connected laptops and recorders), a compromise in one payload’s domain can be leveraged to observe or influence another’s traffic before release. Threat actors exploit these transient but real connections to read configuration, pivot through deployer control paths, or stage data/commands that execute as neighboring payloads power and check out, enabling cross-payload access or tampering prior to independent flight.

Space Threats Addressed by Countermeasure

ID	Description
SV-CF-2	Eavesdropping (RF and proximity)
SV-MA-3	Attacks on critical software subsystems Attitude Determination and Control (AD&C) subsystem determines and controls the orientation of the satellite. Any cyberattack that could disrupt some portion of the control loop - sensor data, computation of control commands, and receipt of the commands would impact operations Telemetry, Tracking and Commanding (TT&C) subsystem provides interface between satellite and ground system. Computations occur within the RF portion of the TT&C subsystem, presenting cyberattack vector Command and Data Handling (C&DH) subsystem is the brains of the satellite. It interfaces with other subsystems, the payload, and the ground. It receives, validate, decodes, and sends commands to other subsystems, and it receives, processes, formats, and routes data for both the ground and onboard computer. C&DH has the most cyber content and is likely the biggest target for cyberattack. Electrical Power Subsystem (EPS) provides, stores, distributes, and controls power on the satellite. An attack on EPS could disrupt, damage, or destroy the satellite.
SV-AC-6	Three main parts of S/C. CPU, memory, I/O interfaces with parallel and/or serial ports. These are connected via busses (i.e., 1553) and need segregated. Supply chain attack on CPU (FPGA/ASICs), supply chain attack to get malware burned into memory through the development process, and rogue RTs on 1553 bus via hosted payloads are all threats. Security or fault management being disabled by non-mission critical or payload; fault injection or MiTM into the 1553 Bus - China has developed fault injector for 1553 - this could be a hosted payload attack if payload has access to main 1553 bus; One piece of FSW affecting another. Things are not containerized from the OS or FSW perspective;

Sample Requirements

SPARTA ID	Requirement	Rationale/Additional Guidance/Notes
SPR-3	The [spacecraft] shall enforce approved authorizations for controlling the flow of information within the platform and between interconnected systems so that information does not leave the platform boundary unless it is encrypted. Flow control shall be implemented in conjunction with protected processing domains, security‑policy filters with fully enumerated formats, and a default‑deny communications baseline.{SV-AC-6}{AC-3(3),AC-3(4),AC-4,AC-4(2),AC-4(6),AC-4(21),CA-3,CA-3(6),CA-3(7),CA-9,IA-9,SA-8(19),SC-8(1),SC-16(3)}	Spacecraft operate in constrained and deterministic environments where uncontrolled data flows can enable data exfiltration, cross-domain leakage, or lateral movement between subsystems. Enforcing approved authorizations with enumerated formats and a default-deny posture ensures only explicitly permitted communications occur. Encryption enforcement at platform boundaries prevents unauthorized disclosure of telemetry or state information.
SPR-4	The [spacecraft] security implementation shall ensure that information should not be allowed to flow between partitioned applications unless explicitly permitted by the system.{SV-AC-6,SV-MA-3,SV-SP-7}{AC-3(3),AC-3(4),AC-4,AC-4(6),AC-4(21),CA-9,IA-9,SA-8(3),SA-8(18),SA-8(19),SC-2(2),SC-7(29),SC-16,SC-32}	Strict partitioning prevents compromise of one application from cascading into mission-critical subsystems. Many spacecraft attacks exploit flat architectures where subsystems implicitly trust one another. Explicit inter-partition authorization limits lateral movement and privilege escalation. This supports containment and fault isolation under both cyber and fault conditions.
SPR-7	The [organization] shall document and design a security architecture using a defense-in-depth approach that allocates the [organization]s defined safeguards to the indicated locations and layers: [Examples include: operating system abstractions and hardware mechanisms to the separate processors in the platform, internal components, and the FSW].{SV-MA-6}{CA-9,PL-7,PL-8,PL-8(1),SA-8(3),SA-8(4),SA-8(7),SA-8(9),SA-8(11),SA-8(13),SA-8(19),SA-8(29),SA-8(30)}	Spacecraft security cannot rely on a single control; layered defenses reduce the likelihood of catastrophic compromise. Documenting safeguard allocation across hardware, OS, firmware, and FSW ensures coverage across attack surfaces. This supports resiliency against both cyber intrusion and supply chain weaknesses. Clear documentation enables verification and independent assessment.
SPR-8	The [organization] shall ensure that the allocated security safeguards operate in a coordinated and mutually reinforcing manner.{SV-MA-6}{CA-7(5),PL-7,PL-8(1),SA-8(19)}	Independent controls that operate in isolation may create security gaps or conflicting behaviors. Coordinated safeguards ensure that encryption, authentication, partitioning, and monitoring functions reinforce each other rather than undermine availability or safety. This reduces bypass risk and improves fault/cyber response integration. Cohesive operation is essential for resilient mission assurance.
SPR-9	The [organization] shall implement a security architecture and design that provides the required security functionality, allocates security controls among physical and logical components, and integrates individual security functions, mechanisms, and processes together to provide required security capabilities and a unified approach to protection.{SV-MA-6}{PL-7,SA-2,SA-8,SA-8(1),SA-8(2),SA-8(3),SA-8(4),SA-8(5),SA-8(6),SA-8(7),SA-8(9),SA-8(11),SA-8(13),SA-8(19),SA-8(29),SA-8(30),SC-32,SC-32(1)}	Security functionality must be intentionally distributed across physical and logical components rather than bolted on post-design. A unified architecture prevents inconsistent enforcement, duplicated controls, or unprotected interfaces. Integrated design reduces attack surface and improves verification of mission-critical protections.
SPR-10	The [spacecraft] shall protect authenticator content from unauthorized disclosure and modification.{SV-AC-1,SV-AC-3}{AC-17(6),CM-3(6),IA-5,IA-5(6),RA-5(4),SA-8(18),SA-8(19),SC-28(3)}	Authenticators (keys, tokens, counters, certificates) are primary targets for persistent access attacks. Disclosure or modification enables command spoofing, replay, and privilege escalation. Protecting authenticator content preserves command integrity and prevents adversaries from maintaining covert control. Integrity protections must apply both at rest and in use.
SPR-11	The [spacecraft] encryption key handling shall be handled outside of the onboard software and protected using cryptography.{SV-AC-1,SV-AC-3}{AC-17(6),CM-3(6),SA-8(19),SA-9(6),SC-8(1),SC-12,SC-28(1),SC-28(3)}	Key management separated from modifiable flight software reduces exposure to software compromise. If keys are accessible to onboard applications, malicious code could extract or misuse them. Hardware-anchored or externally managed key handling reduces persistence risk. This supports trust-chain assurance and mitigates firmware-level compromise.
SPR-12	The [spacecraft] encryption keys shall be restricted so that the onboard software is not able to access the information for key readout.{SV-AC-1,SV-AC-3}{AC-17(6),CM-3(6),SA-8(19),SA-9(6),SC-8(1),SC-12,SC-28(3)}	Even privileged software must not be able to retrieve plaintext keys. Preventing readout mitigates malware harvesting and insider misuse. Key usage should be mediated through cryptographic modules rather than direct exposure. This enforces least privilege at the cryptographic boundary.
SPR-13	The [spacecraft] encryption keys shall be restricted so that they cannot be read via any telecommands.{SV-AC-1,SV-AC-3}{AC-17(6),CM-3(6),SA-8(19),SA-9(6),SC-8(1),SC-12,SC-28(3)}	Telecommand paths are high-value targets for adversarial exploitation. Allowing keys to be retrieved via command interfaces creates a catastrophic failure mode. This constraint prevents exfiltration even under partial compromise of command processing logic. It ensures encryption protections cannot be remotely dismantled.
SPR-14	The [spacecraft] shall authenticate the ground station (and all commands) and other spacecraft before establishing remote connections using bidirectional authentication that is cryptographically based.{SV-AC-1,SV-AC-2}{AC-3,AC-17,AC-17(2),AC-17(10),AC-18(1),AC-20,IA-3(1),IA-4,IA-4(9),IA-7,IA-9,SA-8(18),SA-8(19),SA-9(2),SC-7(11),SC-16(1),SC-16(2),SC-16(3),SC-23(3),SI-3(9)}	Authorization can include embedding opcodes in command strings, using trusted authentication protocols, identifying proper link characteristics such as emitter location, expected range of receive power, expected modulation, data rates, communication protocols, beamwidth, etc.; and tracking command counter increments against expected values.
SPR-15	The [spacecraft] shall implement cryptographic mechanisms to identify and reject wireless transmissions that are deliberate attempts to achieve imitative or manipulative communications deception based on signal parameters.{SV-AV-1,SV-IT-1}{AC-3,AC-20,SA-8(19),SC-8(1),SC-23(3),SC-40(3),SI-4(13),SI-4(24),SI-4(25),SI-10(6)}	Adversaries may attempt imitative RF signals to inject commands or manipulate spacecraft behavior. Signal parameter validation (modulation, power, timing, waveform characteristics) strengthens command authentication beyond cryptographic validation alone. This helps mitigate spoofing, replay, and rogue emitter attacks. RF-layer validation complements cryptographic controls.
SPR-16	The [spacecraft] shall ensure that processes reusing a shared system resource (e.g., registers, main memory, secondary storage) do not have access to information (including encrypted representations of information) previously stored in that resource after formal release, by clearing or zeroizing the resource prior to reuse.{SV-AC-6}{AC-3,PM-32,SA-8(2),SA-8(5),SA-8(6),SA-8(19),SC-4,SI-3}	Residual data in memory or registers can create covert channels or leakage paths between partitions. Zeroization prevents recovery of sensitive data by subsequent processes. This mitigates cross-domain leakage and memory scraping attacks. Clearing encrypted remnants is equally important to prevent cryptanalytic exploitation.
SPR-17	The [spacecraft] shall protect the confidentiality and integrity of all information at rest using cryptography.{SV-CF-1,SV-CF-2,SV-AC-3}{AC-3,SA-8(19),SC-28,SC-28(1),SI-7(6)}	* The intent as written is for all transmitted traffic to be protected. This includes internal to internal communications and especially outside of the boundary.
SPR-18	The [spacecraft] shall protect the confidentiality and integrity of information during preparation for transmission, transmission, and reception, in accordance with the [organization]‑provided encryption matrix.{SV-AC-7}{AC-3,SA-8(19),SC-8,SC-8(1),SC-8(2),SC-16,SC-16(1),SC-40}	* Preparation for transmission and during reception includes the aggregation, packing, and transformation options performed prior to transmission and the undoing of those operations that occur upon receipt.
SPR-19	The [spacecraft] shall encrypt all telemetry on downlink regardless of operating mode to protect current state of spacecraft.{SV-CF-4}{AC-3(10),RA-5(4),SA-8(18),SA-8(19),SC-8,SC-8(1),SC-13}	Telemetry exposes real-time spacecraft state and configuration. Unencrypted telemetry can reveal vulnerabilities, operational status, or targeting information. Enforcing encryption across all modes prevents intelligence collection and mission state inference. This mitigates passive RF interception threats.
SPR-20	The [spacecraft] shall prevent use of a mode of operations where cryptography on the TT&C link can be disabled; encryption and authentication shall remain enabled even when automated access control mechanisms are overridden.{SV-AC-1,SV-CF-1,SV-CF-2}{AC-3(10),SA-8(18),SA-8(19),SC-16(2),SC-16(3),SC-40,SC-40(4)}	Emergency or override modes often become attack vectors if protections are weakened. Cryptography must remain enforced even during safe-mode or degraded operations. Removing encryption capability creates a single-point catastrophic exposure. Persistent protection ensures no operational shortcut undermines mission assurance.
SPR-21	The [spacecraft], when transferring information between different security domains, shall implement security‑policy filters that require fully enumerated formats that restrict data structure and content.{SV-AC-6}{AC-3(3),AC-3(4),AC-4(14),IA-9,SA-8(19),SC-16,SI-10}	Fully enumerated formats prevent injection of malformed or malicious data across security domains. This reduces parser exploitation, data smuggling, and covert channel abuse. Strict domain filtering supports deterministic and auditable inter-domain communication. Only explicitly defined data structures should be permitted.
SPR-22	The [spacecraft] shall implement boundary protections to separate bus, communications, and payload components supporting their respective functions.{SV-AC-6}{AC-3(3),AC-3(4),CA-9,SA-8(3),SA-8(14),SA-8(18),SA-8(19),SA-17(7),SC-2,SC-2(2),SC-7(13),SC-7(21),SC-7(29),SC-16(3),SC-32,SI-3,SI-4(13),SI-4(25)}	Flat architectures allow compromise of one subsystem to impact all others. Segregated boundaries reduce lateral movement and mission degradation. Isolation ensures payload compromise does not impact TT&C or bus control. This supports containment and survivability.
SPR-23	The [spacecraft] shall isolate mission critical functionality from non-mission critical functionality.{SV-AC-6}{AC-3(3),AC-3(4),CA-9,SA-8(3),SA-8(19),SA-17(7),SC-2,SC-3,SC-3(4),SC-7(13),SC-7(29),SC-32,SC-32(1),SI-3,SI-7(10),SI-7(12)}	Non-critical functions often expand attack surface. Isolation prevents less-trusted components from affecting propulsion, attitude control, or power systems. This reduces cascading failure risk under compromise. Mission-critical systems must maintain operational continuity.
SPR-24	The [spacecraft] data within partitioned applications shall not be read or modified by other applications/partitions.{SV-AC-6}{AC-3(3),AC-3(4),SA-8(19),SC-2(2),SC-4,SC-6,SC-32}	Application partitions must enforce strict read/write controls to prevent unauthorized state modification. Without this control, malicious code can alter mission parameters or falsify telemetry. Isolation protects integrity of subsystem data and prevents corruption propagation.
SPR-25	The [spacecraft] shall prevent unauthorized access to system resources by employing an efficient capability based object model that supports both confinement and revocation of these capabilities when the platform security deems it necessary.{SV-AC-6}{AC-3(8),IA-4(9),PM-32,SA-8(2),SA-8(5),SA-8(6),SA-8(18),SA-8(19),SC-2(2),SC-4,SC-16,SC-32,SI-3}	Capability models restrict access to explicit, revocable tokens of authority. This enforces least privilege and supports dynamic revocation under threat conditions. Confinement reduces damage radius of compromised processes. Revocation capability enables adaptive cyber response.
SPR-26	The [spacecraft] shall use protected processing domains to enforce the policy that information does not leave the platform boundary unless it is encrypted as a basis for flow‑control decisions and shall enumerate permitted inter‑domain flows and enforce domain‑gate checks on any domain switch. {SV-AC-6}{AC-4(2),IA-9,SA-8(19),SC-8(1),SC-16(3)}	Domain gates provide controlled transition points between security domains. Enumerated flows prevent unintentional data leakage and enforce encryption policies at boundaries. This mitigates cross-domain injection and exfiltration. Strong gate enforcement prevents privilege escalation during context switching.
SPR-27	The [spacecraft] shall define the security functions and security-relevant information for which the system must protect from unauthorized access.{SV-MA-4,SV-MA-6}{AC-6(1),SA-8(19),SC-7(13),SC-16}	Clearly identifying security-relevant functions ensures protections are applied to the correct assets. Undefined security boundaries create ambiguity and inconsistent enforcement. Explicit definition supports verification, testing, and threat modeling. This forms the basis for risk-informed control allocation.
SPR-28	The [spacecraft] shall provide the capability to enter the platform into a known good, operational cyber-safe mode from a tamper-resistant, configuration-controlled (“gold”) image that is authenticated as coming from an acceptable supplier, and has its integrity verified. The [spacecraft] shall refresh only from cryptographically authenticated [organization]-approved sources.{SV-AV-5,SV-AV-6,SV-AV-7}{CP-10(6),CP-12,CP-13,IR-4(3),SA-8(16),SA-8(19),SA-8(21),SA-8(24),SI-13,SI-17}	Cyber-safe mode is an operating mode of a spacecraft during which all nonessential systems are shut down and the spacecraft is placed in a known good state using validated software and configuration settings. Within cyber-safe mode authentication and encryption should still be enabled. The spacecraft should be capable of reconstituting firmware and SW functions to preattack levels to allow for the recovery of functional capabilities. This can be performed by self-healing, or the healing can be aided from the ground. However, the spacecraft needs to have the capability to replan, based on available equipment still available after a cyberattack. The goal is for the vehicle to resume full mission operations. If not possible, a reduced level of mission capability should be achieved.
SPR-29	The [spacecraft] shall enter cyber-safe mode software/configuration should be stored onboard the spacecraft in memory with hardware-based controls and should not be modifiable.{CP-10(6),CP-13,SA-8(16),SA-8(19),SA-8(21),SA-8(24),SI-17}
SPR-30	The [spacecraft] shall fail to a known secure state for failures during initialization, and aborts preserving information necessary to return to operations in failure.{SV-AV-5,SV-AV-6,SV-AV-7}{CP-10(6),CP-13,SA-8(16),SA-8(19),SA-8(24),SC-24,SI-13,SI-17}
SPR-31	The [spacecraft] shall fail securely to a secondary device in the event of an operational failure of a primary boundary protection device (i.e., crypto solution).{SV-AC-1,SV-AC-2,SV-CF-1,SV-CF-2}{CP-13,SA-8(19),SA-8(24),SC-7(18),SI-13,SI-13(4)}	If a primary boundary protection device fails, the spacecraft must not revert to insecure operation. Secure failover ensures continuity of confidentiality and integrity protections. This prevents adversaries from inducing failure states to bypass encryption. Redundancy strengthens mission resilience.
SPR-32	The [spacecraft] shall provide or support the capability for recovery and reconstitution to a known state after a disruption, compromise, or failure.{SV-AV-5,SV-AV-6,SV-AV-7}{CP-4(4),CP-10,CP-10(4),CP-10(6),CP-13,IR-4,IR-4(1),SA-8(16),SA-8(19),SA-8(24)}
SPR-33	The [spacecraft] shall utilize TRANSEC. TRANSEC shall be implemented and verified as a distinct layer in coordination with Traffic Flow Security and RF anti‑fingerprinting.{SV-AV-1}{CP-8,RA-5(4),SA-8(18),SA-8(19),SC-8(1),SC-8(4),SC-16,SC-16(1),SC-16(2),SC-16(3),SC-40,SC-40(4)}	Transmission Security (TRANSEC) is used to ensure the availability of transmissions and limit intelligence collection from the transmissions. TRANSEC is secured through burst encoding, frequency hopping, or spread spectrum methods where the required pseudorandom sequence generation is controlled by a cryptographic algorithm and key. Such keys are known as transmission security keys (TSK). The objectives of transmission security are low probability of interception (LPI), low probability of detection (LPD), and antijam which means resistance to jamming (EPM or ECCM).
SPR-34	The [spacecraft] shall recover to a known cyber-safe state when an anomaly is detected.{IR-4,IR-4(1),SA-8(16),SA-8(19),SA-8(21),SA-8(24),SI-3,SI-4(7),SI-10(6),SI-13,SI-17}
SPR-35	The [spacecraft] shall perform an orderly, controlled system shut-down to a known cyber-safe state upon receipt of a termination command or condition.{PE-11,PE-11(1),SA-8(16),SA-8(19),SA-8(24),SI-17}
SPR-36	The [spacecraft] shall operate securely in off-nominal power conditions, including loss of power and spurious power transients.{SV-AV-6,SV-MA-2}{PE-11,PE-11(1),SA-8(16),SA-8(19),SI-13,SI-17}	Power anomalies may induce undefined states exploitable by attackers. Cryptographic and security mechanisms must not degrade into insecure configurations during brownout or transient conditions. This mitigates fault-induced bypass attacks. Resilient operation preserves trust chain continuity.
SPR-37	The [spacecraft] shall protect system components, associated data communications, and communication buses in accordance with: (i) national emissions and TEMPEST policies and procedures, and (ii) the security category or sensitivity of the transmitted information, and shall demonstrate compliance via pre‑launch TEMPEST‑like evaluation for co‑located payload configurations.{SV-CF-2,SV-MA-2}{PE-14,PE-19,PE-19(1),RA-5(4),SA-8(18),SA-8(19),SC-8(1)}	The measures taken to protect against compromising emanations must be in accordance with DODD S-5200.19, or superseding requirements. The concerns addressed by this control during operation are emanations leakage between multiple payloads within a single space platform, and between payloads and the bus.
SPR-38	The [spacecraft] shall be designed so that it protects itself from information leakage due to electromagnetic signals emanations.{SV-CF-2,SV-MA-2}{PE-19,PE-19(1),RA-5(4),SA-8(19)}	This requirement applies if system components are being designed to address EMSEC and the measures taken to protect against compromising emanations must be in accordance with DODD S-5200.19, or superseding requirements.
SPR-39	The [spacecraft] shall prevent unauthorized and unintended information transfer via shared system resources.{SV-AC-6}{PM-32,SA-8(2),SA-8(5),SA-8(6),SA-8(19),SC-2(2),SC-4}	Shared buses, memory, or peripherals can become covert channels. Controls must prevent unintended information propagation across shared infrastructure. This mitigates cross-partition leakage and data exfiltration. Shared resources must not undermine domain isolation.
SPR-40	The [spacecraft] shall only use communication protocols that support encryption within the mission.{SV-AC-7,SV-CF-1,SV-CF-2}{SA-4(9),SA-8(18),SA-8(19),SC-40(4)}	Protocols lacking encryption create unavoidable exposure. Selecting encryption-capable protocols ensures confidentiality and integrity can be enforced mission-wide. This reduces risk from protocol downgrade attacks.
SPR-41	The [spacecraft] shall maintain a separate execution domain for each executing process.{SV-AC-6}{SA-8(14),SA-8(19),SC-2(2),SC-7(21),SC-39,SI-3}	Process isolation prevents one compromised task from impacting others. Separate execution domains mitigate memory corruption and privilege escalation. This strengthens containment of malicious code. Deterministic isolation enhances both safety and cybersecurity.
SPR-42	The [spacecraft] flight software shall not be able to tamper with the security policy or its enforcement mechanisms.{SV-AC-6}{SA-8(16),SA-8(19),SC-3,SC-7(13)}	Security enforcement must be independent of mission application logic. If FSW can alter policy, adversaries can disable protections post-compromise. This control preserves integrity of access controls and monitoring functions. Separation of enforcement from application reduces systemic risk.
SPR-43	The [spacecraft] shall initialize the platform to a known safe state.{SA-8(19),SA-8(23),SA-8(24),SI-17}
SPR-44	The [spacecraft] shall maintain the confidentiality and integrity of information during preparation for transmission and during reception in accordance with [organization] provided encryption matrix.{SV-CF-1,SV-CF-2,SV-IT-2}{SA-8(19),SC-8,SC-8(1),SC-8(2),SC-8(3)}	* Preparation for transmission and during reception includes the aggregation, packing, and transformation options performed prior to transmission and the undoing of those operations that occur upon receipt.
SPR-45	The [spacecraft] shall implement cryptographic mechanisms that achieve protection against the effects of intentional electromagnetic interference; verification evidence for EMI/EPM shall be distinct from EMSEC/TEMPEST, anti‑jam/anti‑spoof protections, and EMP/HANE hardness.{SV-AV-1,SV-IT-1}{SA-8(19),SC-8(1),SC-40,SC-40(1)}	Intentional electromagnetic interference may attempt to induce predictable faults or bypass protections. Cryptographic resilience ensures corrupted transmissions are rejected. Verification must distinguish EMI/EPM resilience from TEMPEST and anti-jam protections. This ensures integrity under hostile RF environments.
SPR-60	The [spacecraft] shall integrate cyber related detection and responses with existing fault management capabilities to ensure tight integration between traditional fault management and cyber intrusion detection and prevention.{SV-DCO-1}{AU-6(4),IR-4,IR-4(1),RA-10,SA-8(21),SA-8(26),SC-3(4),SI-3,SI-3(10),SI-4(7),SI-4(13),SI-4(16),SI-4(24),SI-4(25),SI-7(7),SI-13}	The onboard IPS system should be integrated into the existing onboard spacecraft fault management system (FMS) because the FMS has its own fault detection and response system built in. SV corrective behavior is usually limited to automated fault responses and ground commanded recovery actions. Intrusion prevention and response methods will inform resilient cybersecurity design. These methods enable detected threat activity to trigger defensive responses and resilient SV recovery.
SPR-77	The [spacecraft] shall employ the principle of least privilege, allowing only authorized accesses processes which are necessary to accomplish assigned tasks in accordance with system functions.{SV-AC-6}{AC-3,AC-6,AC-6(9),CA-9,CM-5,CM-5(5),CM-5(6),SA-8(2),SA-8(5),SA-8(6),SA-8(14),SA-8(23),SA-17(7),SC-2,SC-7(29),SC-32,SC-32(1),SI-3}	Least privilege limits damage from compromised processes or insider misuse. Processes receive only the minimum access necessary for assigned functions. This reduces lateral movement and privilege escalation pathways. In deterministic spacecraft systems, privilege boundaries must be tightly defined and enforced.
SPR-78	The [spacecraft] shall provide independent mission/cyber critical threads such that any one credible event will not corrupt another mission/cyber critical thread.{SV-AC-6,SV-MA-3,SV-SP-7}{SC-3,SC-32,SC-32(1),SI-3,SI-13}	Segregating mission-critical and cyber-critical execution paths prevents a single failure or compromise from corrupting other critical functions. Thread independence supports fault containment and resilience under attack. This ensures availability of essential functions even during partial compromise. Isolation strengthens both safety and cybersecurity.
SPR-87	The [spacecraft] shall be configured to provide only essential capabilities.{SV-SP-7,SV-SP-1}{CM-6,CM-7,SA-8(2),SA-8(7),SA-8(13),SA-8(23),SA-8(26),SA-15(5)}	Minimizing enabled functionality reduces attack surface and complexity. Unused services create unnecessary exposure. Essential-only configuration aligns with least functionality principles. This simplifies validation and reduces exploit vectors.
SPR-230	The [organization] shall identify and properly classify mission sensitive design/operations information and access control shall be applied in accordance with classification guides and applicable federal laws, Executive Orders, directives, policies, regulations, and standards.{SV-CF-3,SV-AV-5}{AC-3,CM-12,CP-2,PM-17,RA-5(4),SA-3,SA-3(1),SA-5,SA-8(19),SC-8(1),SC-28(3),SI-12}	* Mission sensitive information should be classified as Controlled Unclassified Information (CUI) or formally known as Sensitive but Unclassified. Ideally these artifacts would be rated SECRET or higher and stored on classified networks. Mission sensitive information can typically include a wide range of candidate material: the functional and performance specifications, the RF ICDs, databases, scripts, simulation and rehearsal results/reports, descriptions of uplink protection including any disabling/bypass features, failure/anomaly resolution, and any other sensitive information related to architecture, software, and flight/ground /mission operations. This could all need protection at the appropriate level (e.g., unclassified, SBU, classified, etc.) to mitigate levels of cyber intrusions that may be conducted against the project’s networks. Stand-alone systems and/or separate database encryption may be needed with controlled access and on-going Configuration Management to ensure changes in command procedures and critical database areas are tracked, controlled, and fully tested to avoid loss of science or the entire mission.
SPR-232	The [organization] shall conduct a criticality analysis to identify mission critical functions and critical components and reduce the vulnerability of such functions and components through secure system design.{SV-SP-3,SV-SP-4,SV-AV-7,SV-MA-4}{CP-2,CP-2(8),PL-7,PM-11,PM-30(1),RA-3(1),RA-9,SA-8(9),SA-8(11),SA-8(25),SA-12,SA-14,SA-15(3),SC-7(29),SR-1}	During SCRM, criticality analysis will aid in determining supply chain risk. For mission critical functions/components, extra scrutiny must be applied to ensure supply chain is secured.
SPR-244	The [organization] shall define the secure communication protocols to be used within the mission in accordance with applicable federal laws, Executive Orders, directives, policies, regulations, and standards.{SV-AC-7,SV-CF-1}{PL-7,RA-5(4),SA-4(9),SA-8(18),SA-8(19),SC-8(1),SC-16(3),SC-40(4),SI-12}	Standardized secure protocols reduce interoperability risk. Alignment with federal standards ensures validated cryptography. Defined protocols prevent ad hoc insecure implementations. Governance strengthens communication assurance.
SPR-309	The [organization] shall identify the key system components or capabilities that require isolation through physical or logical means.{SV-AC-6}{AC-3,SC-3,SC-7(13),SC-28(3),SC-32,SC-32(1)}	Fault management and security management capabilities would be classified as mission critical and likely need separated. Additionally, capabilities like TT&C, C&DH, GNC might need separated as well.
SPR-486	The [spacecraft] shall structure security-relevant software and firmware into cohesive modules that expose only [organization]-approved interfaces and prevent unintended cross-module data or control flow. {SV-AC-6}{SC-3,SC-3(4)}	Cohesive modules reduce unintended coupling. Limited interfaces prevent cross-module exploitation. Clear boundaries strengthen isolation. Structured architecture supports resilience.
SPR-487	The [spacecraft] shall verify during integration that modules providing security functions are isolated from non-security modules and that dependencies are limited to documented interfaces.{SV-AC-6}{SC-3,SC-3(4)}	Integration validation ensures isolation is effective. Limiting dependencies reduces lateral risk. Structured interface enforcement strengthens policy assurance. Verification prevents silent drift.
SPR-489	The [spacecraft] shall host privileged functions, including flight control and cryptographic key management, in physically separate processing domains that have no direct data bus connectivity to non privileged domains. {SV-AC-6,SV-AC-3}{SC-3,SC-32(1),SC-39}	Hardware-level separation prevents software bypass. Isolation protects flight control and key management. Physical boundaries strengthen trust. Segmentation enforces zero-trust architecture.
SPR-490	The [spacecraft] shall ensure cross domain exchanges occur only through [organization] defined, verified guards that enforce format, rate, and content checks.{SV-AC-6,SV-IT-2}{AC-4,SC-7,SC-32(1)}	Verified guards ensure controlled data exchange. Format and rate checks prevent covert channel exploitation. Enforced mediation supports mandatory control. Guarded exchange strengthens isolation.

Shared Resource Leakage

Pre-Operations Government

Pre-Operations Developer/Supplier

Sustainment & Maintenance Government

Sustainment & Maintenance Developer/Supplier

NIST Rev5 Controls

D3FEND Techniques

D3FEND Artifacts

ISO 27001

NASA Best Practice Guide

ESA Space Shield Mitigation

Related MITRE EMB3D Mitigations

Related CSF 2.0

Related BSI Security Measures

Techniques Addressed by Countermeasure

Space Threats Addressed by Countermeasure

Sample Requirements