Unauthorized Downlink Communication at Unexpected Time

Monitors downlink communications for unexpected activity, regardless of whether it originates from a transponder, SDR, or other communication component. This ensures detection of potential exfiltration attempts or unauthorized transmissions.

STIX Pattern

[network-traffic:direction = 'downlink' AND network-traffic:timestamp != 'expected_time']

SPARTA TTPs

ID Name Description
EXF-0006 Modify Communications Configuration The adversary alters radio/optical link configuration so the spacecraft emits mission data over paths the program does not monitor or control. Levers include retuning carriers, adding sidebands or subcarriers, changing modulation/coding profiles, remapping virtual channels/APIDs, editing beacon content, or redirecting routing tables in regenerative payloads. Data can be embedded steganographically (idle fields, padding, frame counters, pilot tones) or carried on a covert auxiliary downlink/crosslink pointed at attacker-owned apertures. Because these emissions conform to plausible waveforms and scheduler behavior, they appear as ordinary link activity while quietly conveying payload products, housekeeping, or file fragments to non-mission receivers.
EXF-0006.01 Software Defined Radio Programmable SDRs let an attacker introduce new waveforms or piggyback payloads into existing ones. By modifying DSP chains (filters, mixers, FEC, framing), the actor can: add a low-rate subcarrier under the main modulation, alter preamble/pilot sequences to encode bits, vary puncturing/interleaver patterns as a covert channel, or schedule brief “maintenance” bursts that actually carry exfiltrated data. Changes may be packaged as legitimate updates or configuration profiles so the SDR transmits toward attacker-visible geometry using standard equipment, while mission tooling interprets the emission as routine.
EXF-0006.02 Transponder On bent-pipe or regenerative transponders, configuration controls what is translated, amplified, and routed. An adversary can remap input–output paths, shift translation frequencies, adjust polarization or gain to favor non-mission receivers, or enable auxiliary ports so selected virtual channels or recorder playbacks are forwarded outside the planned ground segment. In regenerative systems, edited routing tables or QoS rules can mirror traffic to an attacker-controlled endpoint. The result is a sanctioned-looking carrier that quietly delivers mission data to unauthorized listeners.