Aerial Acquisition of TEMPEST Signals from Electromagnetic Emissions

Recent research has established that video display cables can be manipulated to emit standardscompliant LoRa packets, creating a structured and decodable covert channel known as TEMPEST-LoRa. While prior research demonstrated drone-based reception of optical covert channels from air-gapped networks, the aerial reception of electromagnetic emanations has remained largely underexplored. This paper demonstrates the feasibility of intercepting electromagnetic TEMPEST signals using a commercial-off-the-shelf DJI drone equipped with a custom relay. Experimental flights confirm that structured emanations from an HDMI cable can be successfully acquired in transit. During a flight of approximately two minutes, the relay captured and retransmitted 91 frames with a mean Received Signal Strength Indicator (RSSI) of −103.0 dBm and a Signal-to-Noise Ratio (SNR) of −6.6 dB. These results indicate that UAV motor noise and vibration do not preclude the reception of narrowband TEMPEST signals. The implications of this finding for airgapped threat modeling are analyzed alongside a discussion of potential countermeasures and technical enhancements such as Doppler compensation and emitter localization.