Tapping of communications links (wireline, RF, network) resulting in loss of confidentiality; Traffic analysis to determine which entities are communicating with each other without being able to read the communicated information
The spacecraft shall protect communication links from loss in confidentiality.
Low-Level Requirements
Requirement
Rationale/Additional Guidance/Notes
The spacecraft shall not employ a mode of operations where cryptography on the TT&C link can be disabled (i.e., crypto-bypass mode). {SV-AC-1,SV-CF-1,SV-CF-2} {AC-3(10)}
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} {SC-7(18)}
The spacecraft shall implement cryptography for the indicated uses using the indicated protocols, algorithms, and mechanisms, in accordance with applicable federal laws, Executive Orders, directives, policies, regulations, and standards: [NSA- certified or approved cryptography for protection of classified information, FIPS-validated cryptography for the provision of hashing]. {SV-AC-1,SV-AC-2,SV-CF-1,SV-CF-2,SV-AC-3} {IA-7,SC-13}
Threat actors may seek to capture network communications throughout the ground station and radio frequency (RF) communication used for uplink and downlink communications. RF communication frequencies vary between 30MHz and 60 GHz. Threat actors may capture RF communications using specialized hardware, such as software defined radio (SDR), handheld radio, or a computer with radio demodulator turned to the communication frequency. Network communications may be captured using packet capture software while the threat actor is on the target network.
Threat actors may capture the RF communications as it pertains to the uplink to the victim spacecraft. This information can contain commanding information that the threat actor can use to perform other attacks against the victim spacecraft.
Threat actors may capture the RF communications as it pertains to the downlink of the victim spacecraft. This information can contain important telemetry such as onboard status and mission data.
Threat actors may capture signals and/or network communications as they travel on-board the vehicle (i.e., EMSEC/TEMPEST), via RF, or terrestrial networks. This information can be decoded to determine commanding and telemetry protocols, command times, and other information that could be used for future attacks.
Threat actors may interfere with the link by actively transmitting packets to activate the transmitter and induce a reply. The scan can be similar to a brute force attack, aiming to guess the used frequencies and protocols to obtain a reply.
Threat actors may gather information regarding safe-mode indicators on the victim spacecraft. Safe-mode is when all non-essential systems are shut down and only essential functions within the spacecraft are active. During this mode, several commands are available to be processed that are not normally processed. Further, many protections may be disabled at this time.
Threat actors may take advantage of the victim spacecraft being in safe mode and send malicious commands that may not otherwise be processed. Safe-mode is when all non-essential systems are shut down and only essential functions within the spacecraft are active. During this mode, several commands are available to be processed that are not normally processed. Further, many protections may be disabled at this time.
Threat actors may use a side-channel attack attempts to gather information or influence the program execution of a system by measuring or exploiting indirect effects of the spacecraft. Side-Channel attacks can be active or passive. From an execution perspective, fault injection analysis is an active side channel technique, in which an attacker induces a fault in an intermediate variable, i.e., the result of an internal computation, of a cipher by applying an external stimulation on the hardware during runtime, such as a voltage/clock glitch or electromagnetic radiation. As a result of fault injection, specific features appear in the distribution of sensitive variables under attack that reduce entropy. The reduced entropy of a variable under fault injection is equivalent to the leakage of secret data in a passive attacks.
Threat actors may exfiltrate data by replaying commands and capturing the telemetry or payload data as it is sent down. One scenario would be the threat actor replays commands to downlink payload data once the spacecraft is within certain location so the data can be intercepted on the downlink by threat actor ground terminals.
Threat actors may use a side-channel attack attempts to gather information by measuring or exploiting indirect effects of the spacecraft. Information within the spacecraft can be extracted through these side-channels in which sensor data is analyzed in non-trivial ways to recover subtle, hidden or unexpected information. A series of measurements of a side-channel constitute an identifiable signature which can then be matched against a signature database to identify target information, without having to explicitly decode the side-channel.
Threat actors may seek to capture network communications throughout the ground station and communication channel (i.e. radio frequency, optical) used for uplink and downlink communications
Threat actors may target the uplink connection from the victim ground infrastructure to the target spacecraft in order to exfiltrate commanding data. Depending on the implementation (i.e., encryption) the captured uplink data can be used to further other attacks like command link intrusion, replay, etc.
Threat actors may target the downlink connection from the victim spacecraft in order to exfiltrate telemetry or payload data. This data can include health information of the spacecraft or mission data that is being collected/analyzed on the spacecraft. Downlinked data can even include mirrored command sessions which can be used for future campaigns or to help perpetuate other techniques.
Threat actors may attempt to exfiltrate data via the out-of-band communication channels. While performing eavesdropping on the primary/second uplinks and downlinks is a method for exfiltration, some space vehicles leverage out-of-band communication links to perform actions on the space vehicle (i.e., re-keying). These out-of-band links would occur on completely different channels/frequencies and often operate on separate hardware on the space vehicle. Typically these out-of-band links have limited built-for-purpose functionality and likely do not present an initial access vector but they do provide ample exfiltration opportunity.
Threat actors may leverage the lack of emission security or tempest controls to exfiltrate information using a visiting spacecraft. This is similar to side-channel attacks but leveraging a visiting spacecraft to measure the signals for decoding purposes.
Threat actors may attempt to steal the data that is being gathered, processed, and sent from the victim spacecraft. Many spacecraft have a particular purpose associated with them and the data they gather is deemed mission critical. By attempting to steal this data, the mission, or purpose, of the spacecraft could be lost entirely.
This technique is a result of utilizing TTPs to create an impact and the applicable countermeasures are associated with the TTPs leveraged to achieve the impact
Organizations should look to identify and properly classify mission sensitive design/operations information (e.g., fault management approach) and apply access control accordingly. Any location (ground system, contractor networks, etc.) storing design information needs to ensure design info is protected from exposure, exfiltration, etc. Space system sensitive information may be classified as Controlled Unclassified Information (CUI) or Company Proprietary. Space system sensitive information can typically include a wide range of candidate material: the functional and performance specifications, any ICDs (like radio frequency, ground-to-space, etc.), command and telemetry 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, CUI, proprietary, 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. Sensitive documentation should only be accessed by personnel with defined roles and a need to know. Well established access controls (roles, encryption at rest and transit, etc.) and data loss prevention (DLP) technology are key countermeasures. The DLP should be configured for the specific data types in question.
Conduct a criticality analysis to identify mission critical functions, critical components, and data flows and reduce the vulnerability of such functions and components through secure system design. Focus supply chain protection on the most critical components/functions. Leverage other countermeasures like segmentation and least privilege to protect the critical components.
A component of cybersecurity to deny unauthorized persons information derived from telecommunications and to ensure the authenticity of such telecommunications. COMSEC includes cryptographic security, transmission security, emissions security, and physical security of COMSEC material. It is imperative to utilize secure communication protocols with strong cryptographic mechanisms to prevent unauthorized disclosure of, and detect changes to, information during transmission. Systems should also maintain the confidentiality and integrity of information during preparation for transmission and during reception. Spacecraft should not employ a mode of operations where cryptography on the TT&C link can be disabled (i.e., crypto-bypass mode). The cryptographic mechanisms should identify and reject wireless transmissions that are deliberate attempts to achieve imitative or manipulative communications deception based on signal parameters.
Leverage best practices for crypto key management as defined by organization like NIST or the National Security Agency. Leverage only approved cryptographic algorithms, cryptographic key generation algorithms or key distribution techniques, authentication techniques, or evaluation criteria. Encryption key handling should be performed outside of the onboard software and protected using cryptography. Encryption keys should be restricted so that they cannot be read via any telecommands.
Authenticate all communication sessions (crosslink and ground stations) for all commands before establishing remote connections using bidirectional authentication that is cryptographically based. Adding authentication on the spacecraft bus and communications on-board the spacecraft is also recommended.
Utilizing techniques to assure traffic flow security and confidentiality to mitigate or defeat traffic analysis attacks or reduce the value of any indicators or adversary inferences. This may be a subset of COMSEC protections, but the techniques would be applied where required to links that carry TT&C and/or data transmissions (to include on-board the spacecraft) where applicable given value and attacker capability. Techniques may include but are not limited to methods to pad or otherwise obfuscate traffic volumes/duration and/or periodicity, concealment of routing information and/or endpoints, or methods to frustrate statistical analysis.
The spacecraft should protect system components, associated data communications, and communication buses in accordance with TEMPEST controls to prevent side channel / proximity attacks. Encompass the spacecraft critical components with a casing/shielding so as to prevent access to the individual critical components.
In addition to authentication on-board the spacecraft bus, encryption is also recommended to protect the confidentiality of the data traversing the bus.
Terminate the connection associated with a communications session at the end of the session or after an acceptable amount of inactivity which is established via the concept of operations.
Provide additional protection modes for commanding the spacecraft. These can be where the spacecraft will restrict command lock based on geographic location of ground stations, special operational modes within the flight software, or even temporal controls where the spacecraft will only accept commands during certain times.
According to Securing Sensor Nodes Against Side Channel Attacks, it is practically inefficient to prevent adversaries from identifying aggregator nodes in a network (i.e., constellation) because camouflaging traffic in sensor networks is power intensive. Consequently, focus on preventing adversaries from identifying valid aggregation cycles of aggregator nodes. One solution to counter such attacks is to have each aggregator node execute dummy operations that resemble the average power consumption curve observed during the normal operation of the aggregator node. Apart from simulating the power consumption of a genuine process execution, the two necessities that the execution of the dummy process must incorporate to be successful in thwarting the accumulation phase are to use a different dummy execution process each time or have a low repetition rate. This should help prevent the attacker from finding a pattern that would differentiate the execution of a dummy process from the normal execution of an aggregator node. The second requirement relates to the timing of the execution of the dummy process. Depending on whether there is a pattern to the timing of the execution of a dummy process, a threat actor may be able to identify and disregard the dummy process. For example, if a threat actor is capable of identifying the presence or absence of a radio frequency transmission, the attacker can disregard any power consumption curve computed during the absence of transmission signal. Similarly, if the dummy process is not executed every time the aggregator node receives a transmission, the attacker will be able to identify invalid transmission. Hence, to ensure the effectiveness of this scheme, the dummy process must be executed each time the aggregator receives a transmission as well as randomly during idle periods. The advantage of incorporating dummy processes in an aggregator is to minimize the ease of identifying transmission flow in a sensor network that can be used to identify the base station of the sensor network, which could be highly confidential in critical applications.
This countermeasure is focused on the protection of terrestrial assets like ground networks and development environments/contractor networks, etc. Traditional detection technologies and capabilities would be applicable here. Utilizing resources from NIST CSF to properly secure these environments using identify, protect, detect, recover, and respond is likely warranted. Additionally, NISTIR 8401 may provide resources as well since it was developed to focus on ground-based security for space systems (https://nvlpubs.nist.gov/nistpubs/ir/2022/NIST.IR.8401.ipd.pdf). Furthermore, the MITRE ATT&CK framework provides IT focused TTPs and their mitigations https://attack.mitre.org/mitigations/enterprise/. Several recommended NIST 800-53 Rev5 controls are provided for reference when designing ground systems/networks.
Monitor defined telemetry points for malicious activities (i.e., jamming attempts, commanding attempts (e.g., command modes, counters, etc.)). This would include valid/processed commands as well as commands that were rejected. Telemetry monitoring should synchronize with ground-based Defensive Cyber Operations (i.e., SIEM/auditing) to create a full space system situation awareness from a cybersecurity perspective.
Attempt to cloak when in safe-mode and ensure that when the system enters safe-mode it does not disable critical security features. Ensure basic protections like encryption are still being used on the uplink/downlink to prevent eavesdropping.
Utilize on-board intrusion detection/prevention system that monitors the mission critical components or systems and audit/logs actions. The IDS/IPS should have the capability to respond to threats (initial access, execution, persistence, evasion, exfiltration, etc.) and it should address signature-based attacks along with dynamic never-before seen attacks using machine learning/adaptive technologies. The IDS/IPS must integrate with traditional fault management to provide a wholistic approach to faults on-board the spacecraft. Spacecraft should select and execute safe countermeasures against cyber-attacks. These countermeasures are a ready supply of options to triage against the specific types of attack and mission priorities. Minimally, the response should ensure vehicle safety and continued operations. Ideally, the goal is to trap the threat, convince the threat that it is successful, and trace and track the attacker — with or without ground support. This would support successful attribution and evolving countermeasures to mitigate the threat in the future. “Safe countermeasures” are those that are compatible with the system’s fault management system to avoid unintended effects or fratricide on the system.
Ensure fault management system cannot be used against the spacecraft. Examples include: safe mode with crypto bypass, orbit correction maneuvers, affecting integrity of telemetry to cause action from ground, or some sort of proximity operation to cause spacecraft to go into safe mode. Understanding the safing procedures and ensuring they do not put the spacecraft in a more vulnerable state is key to building a resilient spacecraft.
Provide the capability to enter the spacecraft into a configuration-controlled and integrity-protected state representing a known, operational cyber-safe state (e.g., cyber-safe mode). Spacecraft should enter a cyber-safe mode when conditions that threaten the platform are detected. 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 software functions to pre-attack 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 equipment still available after a cyber-attack. The goal is for the spacecraft to resume full mission operations. If not possible, a reduced level of mission capability should be achieved. Cyber-safe mode software/configuration should be stored onboard the spacecraft in memory with hardware-based controls and should not be modifiable.
To counter fault analysis attacks, it is recommended to use redundancy to catch injected faults. For certain critical functions that need protected against fault-based side channel attacks, it is recommended to deploy multiple implementations of the same function. Given an input, the spacecraft can process it using the various implementations and compare the outputs. A selection module could be incorporated to decide the valid output. Although sensor nodes have limited resources, critical regions usually comprise the crypto functions, which must be secured.
Using a tamper resistant body can increase the one-time cost of the sensor node but will allow the node to conserve the power usage when compared with other countermeasures.
Power randomization is a technique in which a hardware module is built into the chip that adds noise to the power consumption. This countermeasure is simple and easy to implement but is not energy efficient and could be impactful for size, weight, and power which is limited on spacecraft as it adds to the fabrication cost of the device.
Design hardware circuits or perform obfuscation in general that mask the changes in power consumption to increase the cost/difficulty of a power analysis attack. This will increase the cost of manufacturing sensor nodes.
Use of secret shares in which the original computation is divided probabilistically such that the power subset of shares is statistically independent. One of the major drawbacks of this solution is the increase in the power consumption due to the number of operations that are almost doubled.
Masking is a scheme in which the intermediate variable is not dependent on an easily accessible subset of secret key. This results in making it impossible to deduce the secret key with partial information gathered through electromagnetic leakage.
Use more clock cycles such that branching does not affect the execution time. Also, the memory access times should be standardized to be the same over all accesses. If timing is not mission critical and time is in abundance, the access times can be reduced by adding sufficient delay to normalize the access times. These countermeasures will result in increased power consumption which may not be conducive for low size, weight, and power missions.
Use a dual layered case with the inner layer a highly conducting surface and the outer layer made of a non-conducting material. When heat is generated from internal computing components, the inner, highly conducting surface will quickly dissipate the heat around. The outer layer prevents accesses to the temporary hot spots formed on the inner layer.
Establish alternate physical medium for networking based on threat model/environment. For example, fiber optic cabling is commonly perceived as a better choice in lieu of copper for mitigating network security concerns (i.e., eavesdropping / traffic flow analysis) and this is because optical connections transmit data using light, they don’t radiate signals that can be intercepted.
A protocol is a set of rules (i.e., formats and procedures) to implement and control some type of association (e.g., communication) between systems. Protocols can have vulnerabilities within their specification and may require updating or refactoring based on vulnerabilities or emerging threats (i.e., quantum computing).
Utilize TRANSEC in order to prevent interception, disruption of reception, communications deception, and/or derivation of intelligence by analysis of transmission characteristics such as signal parameters or message externals. Note: TRANSEC is that field of COMSEC which deals with the security of communication transmissions, rather than that of the information being communicated.