The little seal bug: Optical sound recovery from lightweight reflective objects

Ben Nassi, Raz Swissa, Jacob Shams, Boris Zadov, Yuval Elovici

2023 IEEE Security and Privacy Workshops (SPW), 298-310, 2023

In recent years, various studies have demonstrated methods to recover sound/speech with an optical sensor. Fortunately, each of these methods possess drawbacks limiting their utility (e.g., limited to recovering sounds at high volumes, utilize a sensor indicating their use, rely on objects not commonly found in offices, require preliminary data collection, etc.). One unaddressed method of recovering speech optically is via observing lightweight reflective objects (e.g., iced coffee can, smartphone stand, desk ornament) with a photodiode, an optical sensor used to convert photons to electricity. In this paper, we present the ‘little seal bug’ attack, an optical side-channel attack which exploits fluctuations in air pressure on the surface of a shiny object occurring in response to sound, to recover speech optically and passively using a photodiode. These air pressure fluctuations cause the shiny object to vibrate and reflect light …