EMFuzz: Use Electromagnetic Fuzzing for Automated Attack Surface Assessment of Actuators

Actuators are essential components in cyber-physical systems, enabling system modules to perform diverse and complex tasks. Unfortunately, the pursuit of higher functional complexity often correlates with a broader attack surface in actuators. Thus, an efficient automated attack surface assessment is crucial to avoid cyber incidents in critical infrastructures. Limited by enormous parameter spaces, current methods rely on heuristic tests to evaluate interference potential but cannot thoroughly investigate the full spectrum of potential hidden interference. The observation that similar interference trigger configurations lead to the same impact has motivated us to use machine learning algorithms for understanding different impact samples around decision boundaries. By leveraging generalized knowledge of responses against specific attack scenarios, we aim to improve the efficiency of automated attack surface assessment of electromagnetic interference on new targets. To this end, we introduce EMFuzz, an automated mechanism to fuzz hardware to quantify varying adverse effects. We evaluate EMFuzz on 16 new servos within real-world scenarios, where it achieves an 86% accuracy in classifying different attack vectors. With the same test time, EMFuzz uncovers over twice the effective attack configurations of the baseline, greatly improving assessment efficiency. To further validate its efficacy, we apply EMFuzz to assess the attack surface of a new actuator from a robot transfer unit, and it can successfully reveal three distinct adverse effects.