Randomized row-swap: mitigating Row Hammer by breaking spatial correlation between aggressor and victim rows

Abstract

Row Hammer is a fault-injection attack in which rapid activations to a single DRAM row causes bit-flips in nearby rows. Several recent defenses propose tracking aggressor-rows and applying mitigating action on neighboring victim rows by refreshing them. However, all such proposals using victim-focused mitigation preserve the spatial connection between victim and aggressor rows. Therefore, these proposals are susceptible to access patterns causing bit-flips in rows beyond the immediate neighbor. For example, the Half-Double attack causes bit-flips in the presence of victim-focused mitigation.