Using Power-Anomalies to Counter Evasive Micro-Architectural Attacks in Embedded Systems

Abstract

High-assurance embedded systems are deployed for decades and expensive to re-certify – hence, each new attack is an unpatchable problem that can only be detected by monitoring out-of-band channels such as the system’s power trace or electromagnetic emissions. Micro-Architectural attacks, for example, have recently come to prominence since they break all existing software-isolation based security – for example, by hammering memory rows to gain root privileges or by abusing speculative execution and shared hardware to leak secret data. This work is the first to use anomalies in an embedded system’s power trace to detect evasive micro-architectural attacks. To this end, we introduce power-mimicking micro-architectural attacks – including DRAM-rowhammer attacks, side/covert-channel and speculation-driven attacks – to study their evasiveness. We then quantify the operating range of the power-anomalies detector using the Odroid XU3 board – showing that rowhammer attacks cannot evade detection while covert channel and speculation-driven attacks can evade detection but are forced to operate at a 36× and 7× lower bandwidth. Our power-anomaly detector is efficient and can be embedded-of-band into (e.g.,) programmable batteries. While rowhammer, side-channel, and speculation-driven attack defenses require invasive code- and hardware-changes in general-purpose systems, we show that power-anomalies are a simple and effective defense for embedded systems. Power-anomalies can help future-proof embedded systems against vulnerabilities that are likely to emerge as new hardware like phase-change memories and accelerators become mainstream.