YOLO: frequently resetting cyber-physical systems for security

A Cyber-Physical System (CPS) is defined by its unique interactions between digital (cyber) computation and physical motion. Their hybrid nature introduces new attack vectors, but also provides an opportunity to design new security defenses. In this paper, we present a new domain-specific security mechanism, YOLO, that leverages physical properties such as inertia to improve security. YOLO is simple to describe. It goes through two operations: Reset and Diversify, as frequently as possible – typically in the order of a few seconds. Resets mitigate attacks that aim to achieve persistence and enhance the power of diversification techniques. Due to inertia, CPSs can remain safe even under frequent resets. We introduce an analytical approach to evaluate the feasibility of a YOLO-ized system. Using this analytical model we define the constraints on reset periods in order to maintain the CPS's stability. We evaluate our approach in simulation and on two real systems: an engine control unit (ECU) of a car and a flight controller (FC) of a quadcopter. From our experiments, we determine that resets can be triggered frequently, as fast as every 125ms for the ECU and every second for the FC, without violating safety.