Near-Ultrasound Inaudible Trojan (Nuit): Exploiting Your Speaker to Attack Your Microphone


Qi Xia and Qian Chen, University of Texas at San Antonio; Shouhuai Xu, University of Colorado Colorado Springs


Voice Control Systems (VCSs) offer a convenient interface for issuing voice commands to smart devices. However, VCS security has yet to be adequately understood and addressed as evidenced by the presence of two classes of attacks: (i) inaudible attacks, which can be waged when the attacker and the victim are in proximity to each other; and (ii) audible attacks, which can be waged remotely by embedding attack signals into audios. In this paper, we introduce a new class of attacks, dubbed near-ultrasound inaudible trojan (Nuit). Nuit attacks achieve the best of the two classes of attacks mentioned above: they are inaudible and can be waged remotely. Moreover, Nuit attacks can achieve end-to-end unnoticeability, which is important but has not been paid due attention in the literature. Another feature of Nuit attacks is that they exploit victim speakers to attack victim microphones and their associated VCSs, meaning the attacker does not need to use any special speaker. We demonstrate the feasibility of Nuit attacks and propose an effective defense against them.

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@inproceedings {287266,
author = {Qi Xia and Qian Chen and Shouhuai Xu},
title = {{Near-Ultrasound} Inaudible Trojan (Nuit): Exploiting Your Speaker to Attack Your Microphone},
booktitle = {32nd USENIX Security Symposium (USENIX Security 23)},
year = {2023},
isbn = {978-1-939133-37-3},
address = {Anaheim, CA},
pages = {4589--4606},
url = {},
publisher = {USENIX Association},
month = aug

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