Backdoor Commands

Techniques Addressed by Countermeasure

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ID		Name	Description
EX-0006		Disable/Bypass Encryption	Threat actors may perform specific techniques in order to bypass or disable the encryption mechanism onboard the victim SV. By bypassing or disabling this particular mechanism, further tactics can be performed, such as Exfiltration, that may have not been possible with the internal encryption process in place.
PER-0002		Backdoor	Threat actors may find and target various backdoors, or inject their own, within the victim SV in the hopes of maintaining their attack.
	.01	Hardware	Threat actors may find and target various hardware backdoors within the victim SV in the hopes of maintaining their attack. Once in orbit, mitigating the risk of various hardware backdoors becomes increasingly difficult for ground controllers. By targeting these specific vulnerabilities, threat actors are more likely to remain persistent on the victim SV and perpetuate further attacks.
	.02	Software	Threat actors may inject code to create their own backdoor to establish persistent access to the SV. This may be done through modification of code throughout the software supply chain or through modification of the software-defined radio configuration (if applicable).

Space Threats Addressed by Countermeasure

ID	Description

Low-Level Requirements

Requirement	Rationale/Additional Guidance/Notes
The [organization] shall perform analysis of critical backdoor commands that could adversely affect mission success if used maliciously.{SI-10,SI-10(3)}
The [spacecraft] shall monitor security relevant telemetry points for malicious commanding attempts.{AC-17,AC-17(1),AC-17(10),AU-3(1),RA-10,SC-7,SC-16,SC-16(2),SC-16(3),SI-3(8),SI-4,SI-4(1),SI-4(13),SI-4(24),SI-4(25),SI-10(6)}
The [spacecraft] shall accept hazardous commands only when prerequisite checks are satisfied.{AC-17(4),SI-10,SI-10(6)}
The [spacecraft] shall restrict the use of information inputs to spacecraft and designated ground stations as defined in the applicable ICDs.{SV-AC-1,SV-AC-2}{AC-20,SC-23,SI-10,SI-10(5),SI-10(6)}
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)}
The [spacecraft] shall require multi-factor authorization for all spacecraft [applications or operating systems] updates within the spacecraft.{SV-SP-9,SV-SP-11}{AC-3(2),CM-3(8),CM-5,PM-12,SA-8(8),SA-8(31),SA-10(2),SI-3(8),SI-7(12),SI-10(6)}	The intent is for multiple checks to be performed prior to executing these SV SW updates. One action is mere act of uploading the SW to the spacecraft. Another action could be check of digital signature (ideal but not explicitly required) or hash or CRC or a checksum. Crypto boxes provide another level of authentication for all commands, including SW updates but ideally there is another factor outside of crypto to protect against FSW updates. Multi-factor authorization could be the "two-man rule" where procedures are in place to prevent a successful attack by a single actor (note: development activities that are subsequently subject to review or verification activities may already require collaborating attackers such that a "two-man rule" is not appropriate).
All [spacecraft] commands which have unrecoverable consequence must have dual authentication prior to command execution.{AU-9(5),IA-3,IA-4,IA-10,PE-3,PM-12,SA-8(15),SA-8(21),SC-16(2),SC-16(3),SI-3(8),SI-3(9),SI-4(13),SI-4(25),SI-7(12),SI-10(6),SI-13}
The [spacecraft] shall have a method to ensure the integrity of these commands and validate their authenticity before execution.{AU-9(5),IA-3,IA-4,IA-10,PE-3,PM-12,SA-8(15),SA-8(21),SC-16(2),SC-16(3),SI-3(8),SI-3(9),SI-4(13),SI-4(25),SI-7(12),SI-10(6),SI-13}
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}
The [spacecraft] shall detect and recover from detected memory errors or transitions to a known cyber-safe state.{IR-4,IR-4(1),SA-8(16),SA-8(24),SI-3,SI-4(7),SI-10(6),SI-13,SI-17}
The [spacecraft] shall have on-board intrusion detection/prevention system that monitors the mission critical components or systems.{SV-AC-1,SV-AC-2,SV-MA-4}{RA-10,SC-7,SI-3,SI-3(8),SI-4,SI-4(1),SI-4(7),SI-4(13),SI-4(24),SI-4(25),SI-10(6)}	The mission critical components or systems could be GNC/Attitude Control, C&DH, TT&C, Fault Management.
The [spacecraft] shall discriminate between valid and invalid input into the software and rejects invalid input.{SC-16(2),SI-3(8),SI-10,SI-10(3),SI-10(6)}
The [spacecraft] shall identify and reject commands received out-of-sequence when the out-of-sequence commands can cause a hazard/failure or degrade the control of a hazard or mission.{SC-16(2),SI-4(13),SI-4(25),SI-10,SI-10(6),SI-13}
The [spacecraft] software subsystems shall accept [Program defined hazardous] commands only when prerequisite checks are satisfied.{SV-MA-3,SV-AV-7}{SI-10}
The [spacecraft] software subsystems shall identify and reject commands received out-of-sequence when the out-of-sequence commands can cause a hazard/failure or degrade the control of a hazard or mission.{SV-MA-3,SV-AV-7}{SI-10}
The [spacecraft] software subsystems shall perform prerequisite checks for the execution of hazardous commands.{SV-MA-3,SV-AV-7}{SI-10}
The [organization] shall ensure that all viable commands are known to the mission and SV "owner.{SV-AC-8}{SI-10,SI-10(3)}	This is a concern for bus re-use. It is possible that the manufacturer left previously coded commands in their syntax rather than starting from a clean slate. This leaves potential backdoors and other functionality the mission does not know about.
The [organization] shall perform analysis of critical (backdoor) commands that could adversely affect mission success if used maliciously.{SV-AC-8}{SI-10,SI-10(3)}	Heritage and commercial products often have many residual operational (e.g., hardware commands) and test capabilities that are unidentified or unknown to the end user, perhaps because they were not expressly stated mission requirements. These would never be tested and their effects unknown, and hence, could be used maliciously. Test commands not needed for flight should be deleted from the flight database.
The [spacecraft] shall only use or include [organization]-defined critical commands for the purpose of providing emergency access where commanding authority is appropriately restricted.{SV-AC-8}{SI-10,SI-10(3)}	The intent is protect against misuse of critical commands. On potential scenario is where you could use accounts with different privileges, could require an additional passphrase or require entry into a different state or append an additional footer to a critical command. There is room for design flexibility here that can still satisfy this requirement.
The [spacecraft] software subsystems shall discriminate between valid and invalid input into the software and rejects invalid input.{SV-MA-3,SV-AV-7}{SI-10,SI-10(3)}
The [spacecraft] software subsystems shall properly handle spurious input and missing data.{SV-MA-3,SV-AV-7}{SI-10,SI-10(3)}
The [spacecraft] shall properly handle spurious input and missing data.{SI-10,SI-10(3),SI-10(6)}
The [spacecraft] shall perform prerequisite checks for the execution of hazardous commands.{SI-10,SI-10(6),SI-13}
The [spacecraft] software subsystems shall validate a functionally independent parameter prior to the issuance of any sequence that could remove an inhibit or perform a hazardous action.{SV-MA-3,SV-AV-7}{SI-10(3)}
The [spacecraft] shall validate a functionally independent parameter prior to the issuance of any sequence that could remove an inhibit, or perform a hazardous action.{SI-10(3),SI-10(6),SI-13}
The [spacecraft] shall only use or include critical commands for the purpose of providing emergency access where commanding authority is appropriately restricted.{SI-3(8),SI-10,SI-10(3)}