SegmentPerturb: Effective Black-Box Hidden Voice Attack on Commercial ASR Systems via Selective Deletion

Voice control systems continue becoming more pervasive as they are deployed in mobile phones, smart home devices, automobiles, etc. Commonly, voice control systems have high privileges on the device, such as making a call or placing an order. However, they are vulnerable to voice attacks, which may lead to serious consequences. In this paper, we propose SegmentPerturb which crafts hidden voice commands via inquiring the target models. The general idea of SegmentPerturb is that we separate the original command audio into multiple equal-length segments and apply maximum perturbation on each segment by probing the target speech recognition system. We show that our method is as efficient, and in some aspects outperforms other methods from previous works. We choose four popular speech recognition APIs and one mainstream smart home device to conduct the experiments. Results suggest that this algorithm can generate voice commands which can be recognized by the machine but are hard to understand by a human.