Wattshield: A Power Side-Channel Framework for Detecting Malicious Firmware in Fused Filament Fabrication

With the growing popularity of Additive Manufacturing (AM) and its use in security-sensitive applications, these devices have become lucrative targets for adversaries. Given the globalized nature of the supply chain, a robust security solution to detect malicious firmware and ensure a secure printing process and environment is necessary. While researchers have explored solutions for detecting attacks at the designing and slicing stages of the printing process, the firmware aspect remains underexplored. Moreover, the nature of attacks also allows adversaries to sabotage the printer hardware, which is not detectable by current in-situ monitoring solutions. This paper proposes WattShield, a security framework capable of detecting sabotage attacks on the print object and printing environment. WattShield utilizes the power side channel to capture thermal and kinetic process variables and detect malicious manipulations. It is designed to be minimally intrusive and adaptable to monitor different print geometries without requiring per-object training and profiling. To evaluate the WattShield framework, we employed nine firmware attacks across multiple categories, including intellectual property theft, compromising the print object, and targeting the print environment. Our results demonstrate that WattShield can successfully detect all implemented attacks, raising alerts and generating logs in each instance.