Late Breaking Results: Thermally Assisted RowPress-RowHammer Synergy for Cross-Row Bit Flips

In this work, we shed light on a previously uncharacterized thermal-assisted disturbance vulnerability in modern DDR4 DRAM by exploiting the temperature sensitivity and dense cell layout of scaled memory devices, a phenomenon we call HeatHammer. HeatHammer operates by first RowPressing the near aggressor, keeping it activated long enough to raise its local temperature, delay refresh operations, and erode its electrical isolation, and then RowHammering the far aggressor to induce bit flips in the victim row. This thermally weakened state significantly amplifies disturbance propagation, closely resembling the Half-Double effect [1]. Elevated temperatures accelerate charge leakage, shrink retention time, and reduce sense margins, thereby enabling disturbance effects to traverse through the compromised near aggressor via capacitive coupling and charge sharing. We evaluate this vulnerability on DRAM chips from two leading DRAM manufacturers and demonstrate that HeatHammer can substantially degrade the effectiveness of existing mitigation mechanisms such as Target Row Refresh (TRR).