SUAD: Solid-Channel Ultrasound Injection Attack and Defense to Voice Assistants

Fuente: arXiv
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Main Authors: Liu, Chao, Zhu, Zhezheng, Chen, Hao, Guo, Kaiwen, Wang, Penghao, Li, Xiang-Yang
Format: Preprint
Published: 2025
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author Liu, Chao
Zhu, Zhezheng
Chen, Hao
Guo, Kaiwen
Wang, Penghao
Li, Xiang-Yang
author_facet Liu, Chao
Zhu, Zhezheng
Chen, Hao
Guo, Kaiwen
Wang, Penghao
Li, Xiang-Yang
contents As a versatile AI application, voice assistants (VAs) have become increasingly popular, but are vulnerable to security threats. Attackers have proposed various inaudible attacks, but are limited by cost, distance, or LoS. Therefore, we propose \name~Attack, a long-range, cross-barrier, and interference-free inaudible voice attack via solid channels. We begin by thoroughly analyzing the dispersion effect in solid channels, revealing its unique impact on signal propagation. To avoid distortions in voice commands, we design a modular command generation model that parameterizes attack distance, victim audio, and medium dispersion features to adapt to variations in the solid-channel state. Additionally, we propose SUAD Defense, a universal defense that uses ultrasonic perturbation signals to block inaudible voice attacks (IVAs) without impacting normal speech. Since the attack can occur at arbitrary frequencies and times, we propose a training method that randomizes both time and frequency to generate perturbation signals that break ultrasonic commands. Notably, the perturbation signal is modulated to an inaudible frequency without affecting the functionality of voice commands for VAs. Experiments on six smartphones have shown that SUAD Attack achieves activation success rates above 89.8% and SUAD Defense blocks IVAs with success rates exceeding 98%.
format Preprint
id arxiv_https___arxiv_org_abs_2508_02116
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle SUAD: Solid-Channel Ultrasound Injection Attack and Defense to Voice Assistants
Liu, Chao
Zhu, Zhezheng
Chen, Hao
Guo, Kaiwen
Wang, Penghao
Li, Xiang-Yang
Cryptography and Security
As a versatile AI application, voice assistants (VAs) have become increasingly popular, but are vulnerable to security threats. Attackers have proposed various inaudible attacks, but are limited by cost, distance, or LoS. Therefore, we propose \name~Attack, a long-range, cross-barrier, and interference-free inaudible voice attack via solid channels. We begin by thoroughly analyzing the dispersion effect in solid channels, revealing its unique impact on signal propagation. To avoid distortions in voice commands, we design a modular command generation model that parameterizes attack distance, victim audio, and medium dispersion features to adapt to variations in the solid-channel state. Additionally, we propose SUAD Defense, a universal defense that uses ultrasonic perturbation signals to block inaudible voice attacks (IVAs) without impacting normal speech. Since the attack can occur at arbitrary frequencies and times, we propose a training method that randomizes both time and frequency to generate perturbation signals that break ultrasonic commands. Notably, the perturbation signal is modulated to an inaudible frequency without affecting the functionality of voice commands for VAs. Experiments on six smartphones have shown that SUAD Attack achieves activation success rates above 89.8% and SUAD Defense blocks IVAs with success rates exceeding 98%.
title SUAD: Solid-Channel Ultrasound Injection Attack and Defense to Voice Assistants
topic Cryptography and Security
url https://arxiv.org/abs/2508.02116