DEACT: Hardware Solution to Rowhammer Attacks

Abstract

Dynamic Random Access Memory (DRAM) is a crucial component in modern computing devices. Improvements in process technology have significantly increased the speed and storage capacity of memory devices. However, as memory cells become smaller and closer to one another, annoying circuit disturbance errors such as the Row-hammer problem have become significant. Studies show that attackers can systematically exploit such errors to induce bit flips and take control of local/remote systems. Even though several hardware and software-based mitigation techniques have been proposed, it is still continuing to be a big threat to system security. In this research, we propose DEACT, a counter-based hardware mitigation to the Rowhammer attack. Contrary to existing countermeasures that refresh victim rows or throttle memory access upon excessive row activation, DEACT uses additional row buffers to keep hot rows and prevent further activation. The size of our counter uses 1.67 times less space than the optimal of existing implementations. DEACT not only eliminates the Rowhammer problem, but it also improves the performance of DRAM. We tested DEACT on the TPC and CPU-2006 benchmarks; the average hit rate has increased by 41% when compared to standard DRAM.