AC-3(2) - Access Enforcement | Dual Authorization

Enforce dual authorization for [Assignment: organization-defined privileged commands and/or other organization-defined actions].


Informational References

ISO 27001

ID: AC-3(2)
Enhancement of : AC-3

Countermeasures Covered by Control

ID Name Description D3FEND
CM0054 Two-Person Rule Utilize a two-person system to achieve a high level of security for systems with command level access to the spacecraft. Under this rule all access and actions require the presence of two authorized people at all times. D3-OAM D3-AM D3-ODM D3-OM D3-MFA
CM0055 Secure Command Mode(s) 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. D3-AH D3-ACH D3-MFA D3-OTP

Space Threats Tagged by Control

ID Description
SV-AV-4 Attacking the scheduling table to affect tasking
SV-IT-5 Onboard control procedures (i.e., ATS/RTS) that execute a scripts/sets of commands
SV-SP-9 On-orbit software updates/upgrades/patches/direct memory writes. If TT&C is compromised or MOC or even the developer's environment, the risk exists to do a variation of a supply chain attack where after it is in orbit you inject malicious code
SV-SP-11 Software defined radios - SDR is also another computer, networked to other parts of the spacecraft that could be pivoted to by an attacker and infected with malicious code. Once access to an SDR is gained, the attacker could alter what the SDR thinks is correct frequencies and settings to communicate with the ground.

Sample Requirements

Requirement Rationale/Additional Guidance/Notes
The [organization] shall ensure any update to on-board software, memory, or stored procedures has met high assurance standards before execution. {AC-3(2),CM-3,SA-8(8),SA-8(31),SA-10(2),SR-4(4)}
The [spacecraft] shall require multi-factor authorization for all updates to the task scheduling functionality within the spacecraft.{SV-AV-4}{AC-3(2)} 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).
The [spacecraft] shall require multi-factor authorization for new and updates to on-board stored command sequences.{SV-IT-5}{AC-3(2)} 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).
The [spacecraft] software subsystems shall provide non-identical methods, or functionally independent methods, for commanding a mission critical function when the software is the sole control of that function.{SV-MA-3,SV-AV-7}{AC-3(2)}
The [spacecraft] software subsystems shall provide two independent and unique command messages to deactivate a fault tolerant capability for a critical or catastrophic hazard.{SV-MA-3,SV-AV-7}{AC-3(2)}
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).
The [spacecraft] shall provide two independent and unique command messages to deactivate a fault tolerant capability for a critical or catastrophic hazard.{AC-3(2),PE-10,SA-8(15)}
The [spacecraft] shall provide non-identical methods, or functionally independent methods, for commanding a mission critical function when the software is the sole control of that function.{AC-3(2),SI-3(8),SI-13}

Related SPARTA Techniques and Sub-Techniques

ID Name Description
IA-0003 Crosslink via Compromised Neighbor Threat actors may compromise a victim spacecraft via the crosslink communications of a neighboring spacecraft that has been compromised. spacecraft in close proximity are able to send commands back and forth. Threat actors may be able to leverage this access to compromise other spacecraft once they have access to another that is nearby.
IA-0004 Secondary/Backup Communication Channel Threat actors may compromise alternative communication pathways which may not be as protected as the primary pathway. Depending on implementation the contingency communication pathways/solutions may lack the same level of security (i.e., physical security, encryption, authentication, etc.) which if forced to use could provide a threat actor an opportunity to launch attacks. Typically these would have to be coupled with other denial of service techniques on the primary pathway to force usage of secondary pathways.
IA-0004.01 Ground Station Threat actors may establish a foothold within the backup ground/mission operations center (MOC) and then perform attacks to force primary communication traffic through the backup communication channel so that other TTPs can be executed (man-in-the-middle, malicious commanding, malicious code, etc.). While an attacker would not be required to force the communications through the backup channel vice waiting until the backup is used for various reasons. Threat actors can also utilize compromised ground stations to chain command execution and payload delivery across geo-separated ground stations to extend reach and maintain access on spacecraft. The backup ground/MOC should be considered a viable attack vector and the appropriate/equivalent security controls from the primary communication channel should be on the backup ground/MOC as well.
IA-0007 Compromise Ground System Threat actors may initially compromise the ground system in order to access the target spacecraft. Once compromised, the threat actor can perform a multitude of initial access techniques, including replay, compromising FSW deployment, compromising encryption keys, and compromising authentication schemes. Threat actors may also perform further reconnaissance within the system to enumerate mission networks and gather information related to ground station logical topology, missions ran out of said ground station, birds that are in-band of targeted ground stations, and other mission system capabilities.
IA-0007.01 Compromise On-Orbit Update Threat actors may manipulate and modify on-orbit updates before they are sent to the target spacecraft. This attack can be done in a number of ways, including manipulation of source code, manipulating environment variables, on-board table/memory values, or replacing compiled versions with a malicious one.
IA-0007.02 Malicious Commanding via Valid GS Threat actors may compromise target owned ground systems components (e.g., front end processors, command and control software, etc.) that can be used for future campaigns or to perpetuate other techniques. These ground systems components have already been configured for communications to the victim spacecraft. By compromising this infrastructure, threat actors can stage, launch, and execute an operation. Threat actors may utilize these systems for various tasks, including Execution and Exfiltration.
IA-0008 Rogue External Entity Threat actors may gain access to a victim spacecraft through the use of a rogue external entity. With this technique, the threat actor does not need access to a legitimate ground station or communication site.
IA-0008.01 Rogue Ground Station Threat actors may gain access to a victim spacecraft through the use of a rogue ground system. With this technique, the threat actor does not need access to a legitimate ground station or communication site.
IA-0008.02 Rogue Spacecraft Threat actors may gain access to a target spacecraft using their own spacecraft that has the capability to maneuver within close proximity to a target spacecraft to carry out a variety of TTPs (i.e., eavesdropping, side-channel, etc.). Since many of the commercial and military assets in space are tracked, and that information is publicly available, attackers can identify the location of space assets to infer the best positioning for intersecting orbits. Proximity operations support avoidance of the larger attenuation that would otherwise affect the signal when propagating long distances, or environmental circumstances that may present interference.
IA-0009 Trusted Relationship Access through trusted third-party relationship exploits an existing connection that has been approved for interconnection. Leveraging third party / approved interconnections to pivot into the target systems is a common technique for threat actors as these interconnections typically lack stringent access control due to the trusted status.
IA-0009.02 Vendor Threat actors may target the trust between vendors and the target spacecraft. Missions often grant elevated access to vendors in order to allow them to manage internal systems as well as cloud-based environments. The vendor's access may be intended to be limited to the infrastructure being maintained but it may provide laterally movement into the target spacecraft. Attackers may leverage security weaknesses in the vendor environment to gain access to more critical mission resources or network locations. In the spacecraft context vendors may have direct commanding and updating capabilities outside of the primary communication channel.
EX-0001 Replay Replay attacks involve threat actors recording previously recorded data streams and then resending them at a later time. This attack can be used to fingerprint systems, gain elevated privileges, or even cause a denial of service.
EX-0001.01 Command Packets Threat actors may interact with the victim spacecraft by replaying captured commands to the spacecraft. While not necessarily malicious in nature, replayed commands can be used to overload the target spacecraft and cause it's onboard systems to crash, perform a DoS attack, or monitor various responses by the spacecraft. If critical commands are captured and replayed, thruster fires, then the impact could impact the spacecraft's attitude control/orbit.
DE-0004 Masquerading Threat actors may gain access to a victim spacecraft by masquerading as an authorized entity. This can be done several ways, including through the manipulation of command headers, spoofing locations, or even leveraging Insider's access (i.e., Insider Threat)
LM-0003 Constellation Hopping via Crosslink Threat actors may attempt to command another neighboring spacecraft via crosslink. spacecraft in close proximity are often able to send commands back and forth. Threat actors may be able to leverage this access to compromise another spacecraft.
EXF-0001 Replay 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.