Inaudible Voice Commands

TL;DR

This paper introduces a novel attack method using inaudible ultrasounds to covertly control voice assistants by exploiting microphone non-linearity, demonstrated on Android and Amazon Echo devices with high success rates.

Contribution

The paper presents a new inaudible ultrasound attack technique targeting microphones, overcoming previous audible command detection limitations.

Findings

Successful attack on Android phones and Amazon Echo devices.

Effective at a range of 2-3 meters.

High success rates in real-world experiments.

Abstract

Voice assistants like Siri enable us to control IoT devices conveniently with voice commands, however, they also provide new attack opportunities for adversaries. Previous papers attack voice assistants with obfuscated voice commands by leveraging the gap between speech recognition system and human voice perception. The limitation is that these obfuscated commands are audible and thus conspicuous to device owners. In this paper, we propose a novel mechanism to directly attack the microphone used for sensing voice data with inaudible voice commands. We show that the adversary can exploit the microphone's non-linearity and play well-designed inaudible ultrasounds to cause the microphone to record normal voice commands, and thus control the victim device inconspicuously. We demonstrate via end-to-end real-world experiments that our inaudible voice commands can attack an Android phone and an Amazon Echo device with high success rates at a range of 2-3 meters.