You Can't Always Check What You Wanted: : Selective Checking and Trusted Execution to Prevent False Actuations in Real-Time Internet-of-Things

Modern Internet-of-Things devices are vulnerable to attacks targeting outgoing actuation commands that modify their physical behaviors. We present a 'selective checking' mechanism that uses game-theoretic modeling to identify the suitable subset of commands to be checked in order to deter an adversary. This mechanism is coupled with a 'delay-aware' trusted execution environment to ensure that only verified actuation commands are ever sent to the physical system, thus maintaining the safety and integrity of the system. Our proposed selective checking and trusted execution (SCATE) framework is implemented on an off-the-shelf ARM platform running embedded Linux and tested on four realistic IoT-specific cyber-physical systems (a ground rover, a flight controller, a robotic arm and an automated syringe pump).