Defeating Hardware Prefetchers in Flush+Reload Side-Channel Attack

Hardware prefetching can seriously interfere with Flush+Reload cache side channel attack. This interference is not taken into consideration in previous Flush+Reload attacks. In this paper, an improved Flush+Reload is provided which minimizes the impact of hardware prefetchers. Specifically, prefetching is analyzed based on reverse engineering and the result is used to make an evaluation model to evaluate the impact of hardware prefetching on Flush+Reload attacks. Then the model is applied to fine tune the placement of probes in Flush+Reload attack to mitigate the prefetching impact. The experiments show that the approach is effective on the Core i5 processor which is equipped with highly aggressive prefetchers.