Rowhammer allows an attacker to induce bit flips in a row by rapidly accessing neighboring rows. Rowhammer is not just a reliability concern but a severe security threat as it can be used to escalate privilege or break confidentiality. The problem of Rowhammer continues to become worse for two reasons: (1) The threshold of activations needed to induce Rowhammer reduces with each generation, coming down by 30x in the last 7 years (2) Attackers continue to come up with complex patterns that can break all hardware-based defenses, including the ones commercially employed in current chips.

Currently, there is no guaranteed solution for Rowhammer. Hardware-based mitigation of Rowhammer typically consists of two parts: a tracker to identify aggressor rows and a mitigating action. At low thresholds tracking incurs significant SRAM overheads (several megabytes). Furthermore, the common mitigating action of refreshing neighboring victim rows is susceptible to the Half-Double attack from Google. In this talk, I will discuss our recent solutions that enable low-cost tracking of aggressor rows even at ultra-low thresholds (ISCA’22), a new mitigating action of performing dynamic row migration that is resilient to complex attacks patterns (ASPLOS’22 and MICRO’22), and a Rowhammer-aware ECC design that provides in-built memory integrity-protection while incurring virtually zero performance and storage overheads (HPCA’22).