If you are a hacker who removed microphones from your computer but is worrying about this exploit, fortunately, a simple mitigation is possible - just put an audio amplifier or unity-gain buffer between the speaker and the audio output port, so the audio signal cannot travel back to the audio chip. Any "Hi-Fi" headphone amplifier can be used, but a $0.5 opamp is enough - a daughterboard can be tiny enough to fit inside a laptop.
If you are a hacker who removed microphones from your computer but is worrying about this exploit, fortunately, a simple mitigation is possible - just put an audio amplifier or unity-gain buffer between the speaker and the audio output port, so the audio signal cannot travel back to the audio chip. Any "Hi-Fi" headphone amplifier can be used, but a $0.5 opamp is enough - a daughterboard can be tiny enough to fit inside a laptop.