Subcomponent Timing-Based Detection of Malware in Embedded Systems

Network-connected embedded systems require multiple lines of defense against malware. In addition to preventing malware by designing secure interfaces and software, anomaly-based detection is needed to detect malware that successfully infiltrates these defenses. Timing based anomaly detection strengthens embedded system security by detecting anomalies in the execution time of critical software tasks. However, existing timing based anomaly detection methods use a lumped timing model that aggregates the timing of the software, processor architecture, operating system scheduling, etc., and thereby incurs significant variability. We present a non-intrusive hardware detector supporting two novel timing models, including a lumped timing multi-range model that clusters timing into multiple range bounds, and a subcomponent timing model that defines bounds for timing subcomponents of events. Timing subcomponents include intrinsic software execution, instruction cache misses, data cache misses, and interrupts. The experimental results demonstrate that the detection based on subcomponent timing model achieves greater malware detection accuracy compared to the lumped timing model without increasing false positives.