Audio Hotspot Attack: An Attack on Voice Assistance Systems Using Directional Sound Beams

We propose a novel attack named "Audio Hotspot Attack'', which performs an inaudible malicious voice command attack, targeting voice assistance systems, e.g., smart speakers or in-car navigation systems. This attack leverages directional sound beams generated from parametric loudspeakers, which emit AM-modulated ultrasounds that will be self-demodulated in the air. It can succeed in the attack on a long distance (2--4 meters in a small room and 10+ meter in a long hallway). To evaluate the feasibility of the attack, we performed extensive in-lab experiments and a user study involving 20 participants. The results demonstrate that the attack is feasible in a real-world setting.