Out-of-Band Communications Link

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.

ID: EXF-0004
Related Aerospace Threat IDs:  SV-AC-1 | SV-CF-1
Related MITRE ATT&CK TTPs:  T1644
Created: 2022/10/19
Last Modified: 2022/12/08


ID Name Description NIST Rev5
CM0002 COMSEC 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. AC-17(1) AC-17(10) AC-17(10) AC-17(2) AC-18(1) AC-2(11) AC-3(10) IA-4(9) IA-5 IA-5(7) IA-7 SA-8(18) SA-9(6) SC-10 SC-12 SC-12(1) SC-12(2) SC-12(3) SC-12(6) SC-13 SC-13(1) SC-13(2) SC-16(3) SC-28(1) SC-28(3) SC-7 SC-7(10) SC-7(11) SC-7(18) SC-7(5) SI-10 SI-10(3) SI-10(5) SI-10(6) SI-19(4) SI-3(8)
CM0030 Crypto Key Management 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. SA-9(6) SC-12 SC-12(1) SC-12(2) SC-12(3) SC-12(6) SC-28(3)
CM0031 Authentication 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. AC-17(10) AC-17(10) AC-17(2) AC-18(1) IA-3(1) IA-4 IA-4(9) IA-7 SA-8(15) SA-8(9) SC-16(2) SC-32(1) SC-7(11) SI-14(3)
CM0073 Traffic Flow Analysis Defense 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. SC-8 SI-4(15)
CM0036 Session Termination 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. AC-12 SC-10 SI-14(3)
CM0071 Communication Physical Medium 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. PE-4 SC-8 SC-8(5)
CM0029 TRANSEC 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. AC-18(5) CP-8 SC-40 SC-40(1) SC-40(3) SC-40(4) SC-5 SC-8(4)