Abstract—Direct Memory Access (DMA) attacks have been known for many years: DMA-enabled I/O peripherals have complete access to the state of a computer and can fully compromise it including reading and writing all of system memory. With the popularity of Thunderbolt 3 over USB Type-C and smart internal devices, opportunities for these attacks to be performed casually with only seconds of physical access to a computer have greatly broadened. In response, commodity hardware and operatingsystem (OS) vendors have incorporated support for Input-Ouptut Memory Management Units (IOMMUs), which impose memory protection on DMA, and are widely believed to protect against DMA attacks.

http://thunderclap.io/thunderclap-paper-ndss2019.pdf