Researchers at ETH Zurich have developed ZenHammer, a variant of the Rowhammer DRAM attack tailored for recent AMD Zen CPUs, challenging the belief that these processors are less susceptible to such exploits. By reverse-engineering complex DRAM addressing functions and optimizing memory access patterns, the researchers successfully induced bit flips in DDR4 and DDR5 memory chips on AMD Zen 2, Zen 3, and Zen 4 platforms.
Despite previous assumptions about DDR5’s resilience to Rowhammer attacks due to improved mitigations and higher refresh rates, ZenHammer proved effective, albeit less so compared to DDR4. Successful attacks were demonstrated on AMD Zen 2 and Zen 3 systems, with root privileges obtained in as little as 93 seconds, highlighting the severity of the threat.
In response to ZenHammer, AMD has issued a security bulletin offering mitigation advice and reassurance of thorough assessment and updates. However, users are advised to apply software patches, consider hardware with enhanced Rowhammer protections, and acknowledge the complexity of executing such attacks, requiring deep understanding of software and hardware components.
