Time to Think the Security of WiFi-Based Behavior Recognition Systems

Behavior recognition plays an essential role in numerous behavior-driven applications (e.g., virtual reality and smart home) and even in the security-critical applications (e.g., security surveillance and elder healthcare). Recently, WiFi-based behavior recognition (WBR) technique stands out among many behavior recognition techniques due to its advantages of being non-intrusive, device-free, and ubiquitous. However, existing WBR research mainly focuses on improving the recognition precision, while rarely studying the security aspects. In this article, we reveal that WBR systems are vulnerable to manipulating physical signals. For instance, our observation shows that WiFi signals can be changed by jamming signals. By exploiting the vulnerability, we propose two approaches to generate physically online adversarial samples to perform untargeted attack and targeted attack, respectively. The effectiveness of these attacks are extensively evaluated over four real-world WBR systems. The experiment results show that our attack approaches can achieve 80% and 60% success rates for untargeted attack and targeted attack in physical world, respectively. We also show that our attack approaches can be generalized to other WiFi-based sensing applications, such as user authentication.