Collaborative Research: CSR: Small: Caphammer: A New Security Exploit in Energy Harvesting Systems and its Countermeasures

An energy harvesting system (EHS) has emerged as an alternative to battery-operated Internet of Things (IoT) devices. Instead of using a battery, EHS self-powers its device by collecting ambient energy from external sources such as radio frequency, WiFi, etc. However, since such ambient energy sources are unreliable, their resulting power is inherently unstable and often goes out. To address the problem, EHS leverages a capacitor as an energy buffer and computes when the capacitor secures a sufficient amount of energy, i.e., capacitors are at the heart of any EHS devices. Unfortunately, capacitors can be unreliable in the presence of frequent power failure across which they continuously charge and discharge, losing their original capacitance over time. More importantly, attackers can exploit the capacitor reliability issue to cause incorrect outputs or degrade the quality of service in targeted EHS devices. To this end, this research project focuses on investigating attack surfaces and designing cost-effective countermeasures. The project outcome will lay the foundation for batteryless Internet of Things services by maintaining their quality of service and security. The project also aims to integrate research findings into undergraduate teaching and promote equitable outcomes for women in computer science through K-12 outreach program. This project involves three major research thrusts. First, it introduces a new security attack called capacitor hammering attack (simply Caphammer), which aims to remotely degrade capacitors in the victim EHS devices. By manipulating power failure frequency, this attack can result in data corruption and denial of service (DoS). Second, the project designs a novel energy storage architecture that can effectively prevent the Caphammer attack and restore the original capacitance. This design leverages the unique characteristics of capacitors and EHS to achieve resilience against Caphammer attacks. Third, the project develops a lightweight countermeasure based on intelligent compiler/runtime co-design to prevent data corruption and mitigate the risks of DoS problems by constructing self-recoverable programs. Consequently, these research goals collectively aim to enhance the security and reliability of EHS devices, safeguarding them against other potential attacks that can be launched through Caphammer. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.