Comment by bgbntty2
1 month ago
Remote audio surveillance probably be accomplished on wired headphones with TEMPEST [0]/Van Eck phreaking [1]. Not sure about which has a better range and which would be stealthier - TEMPEST or the Bluetooth attack. The Bluetooth attack just requires a laptop. Not sure if the TEMPEST attack would require a big antenna.
Even if the TEMPEST were easier, it's significantly less powerful, as it's not going to get you the ability to write malicious firmware to the audio device nor a persistent connection to the host device when the audio device isn't connected.
I doubt that audio-spectrum RF/magnetic frequencies emanate strongly from wired headphones. They are simply not a long enough antenna at 200-3,000 Hz. Also, the loop area is quite low. The ground wire runs parallel to the L/R wires, so the only loop to receive is the magnetic coils in the headphones, which are small. Only near field would work, IMO.
Thanks!