Supporting Rowhammer research to protect the DRAM ecosystem

Publisher excerpt From Google Online Security Blog

Posted by Daniel Moghimi Rowhammer is a complex class of vulnerabilities across the industry. It is a hardware vulnerability in DRAM where repeatedly accessing a row of memory can cause bit flips in adjacent rows, leading to data corruption. This can be exploited by attackers to gain unauthorized access to data, escalate privileges, or cause denial of service. Hardware vendors have deployed various mitigations, such as ECC and Target Row Refresh (TRR) for DDR5 memory, to mitigate Rowhammer and enhance DRAM reliability. However, the resilience of those mitigations against sophisticated attackers remains an open question. To address this gap and help the ecosystem with deploying robust defenses, Google has supported academic research and developed test platforms to analyze DDR5 memory. Our effort has led to the discovery of new attacks and a deeper understanding of Rowhammer on the current DRAM modules, helping to forge the way for further, stronger mitigations. What is Rowhammer? Rowhammer exploits a vulnerability in DRAM. DRAM cells store data as electrical charges, but these electric charges leak over time, causing data corruption. To prevent data loss, the memory controller periodically refreshes the cells. However, if a cell discharges before the refresh cycle, its stored bit may corrupt. Initially considered a reliability issue, it has been leveraged by security researchers to demonstrate privilege escalation attacks. By repeatedly accessing a memory row, an attacke…

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