InjectEave differs from conventional electromagnetic eavesdropping because it does not simply listen for signals a device naturally emits. Instead, the attacker transmits a carefully selected radio-frequency signal toward the target. Nonlinear electronic components inside the device, including amplifiers, analog-to-digital converters, power converters, and switching transistors, can unintentionally mix internal analog signals with that injected carrier. The resulting radio emissions can then contain information about the original signal.
The RF equivalent of the old attack of shining a laser on a window, detecting the reflected signal, and extracting from that signal any vibrations on the window caused by sound in the room (and from that reconstructing the original audio signal)? Laser microphone
… with the advantage that the attack in the OP could work even if the target room has no windows.
A landline-phone experiment went a step further. The researchers demonstrated a closed-loop scenario in which electromagnetic techniques could be used both to recover a conversation and to inject manipulated audio back into the phone’s voice interface, combining eavesdropping with signal manipulation.
