Cyber-Physical Firewall: Monitoring and Controlling the Threats Caused by Malicious Analog Signals

This work developed a new security framework named Cyber-Physical Firewall (CPFW), which provides a generic and flexible access control mechanism for regulating the malicious analog signals that target cyber-physical system (CPS) devices. This framework enables the defeat of various attacks that make use of malicious analog signals against CPS devices; e.g., stealth voice command injection attack using ultrasonic waves or adversarial examples, or attacks to crash drones in flight using malicious sound waves. Based on relevant previously reported findings, we first defined the requirements and design specifications of the CPFW framework. Then, we built a prototype CPFW framework and demonstrated its feasibility through extensive performance evaluations and case-study experiments using three real-world attacks; ultrasonic attacks (DolphinAttack), noise attacks (Audio Adversarial Examples), and resonant attacks (WALNUT).