Hacking Voice Assistants with Ultrasonic Waves

I previously wrote about hacking voice assistants with lasers. Turns you can do much the same thing with ultrasonic waves:

> Voice assistants – the demo targeted Siri, Google Assistant, and Bixby – are designed to respond when they detect the owner’s voice after noticing a trigger phrase such as ‘Ok, Google’.
>
> Ultimately, commands are just sound waves, which other researchers have already shown can be emulated using ultrasonic waves which humans can’t hear, providing an attacker has a line of sight on the device and the distance is short.
>
> What SurfingAttack adds to this is the ability to send the ultrasonic commands through a solid glass or wood table on which the smartphone was sitting using a circular piezoelectric disc connected to its underside.
>
> Although the distance was only 43cm (17 inches), hiding the disc under a surface represents a more plausible, easier-to-conceal attack method than previous techniques.

Research paper. Demonstration video.