AMD SEV-SNP attacks let hosts alter memory and fake attestation
ETH Zurich researchers demonstrated two attacks, Mior and Skyfall, against AMD SEV-SNP virtual machines; both can expose guest data, while Mior can also alter memory and forge signed attestation reports.
In Mior, the chip’s Platform Security Processor (PSP) diverts writes to its Reverse Map Table (RMP)—the map of memory-page ownership—to a controlled graphics card while getting plausible readbacks. The real map stays incomplete, so a hypervisor with BIOS control can change protections and use PSP debug commands to read or alter guest memory. Mior can also copy a harmless VM’s measurement into a malicious one, making its signed report misstate the software running.
AMD lists separate firmware and microcode fixes. For organizations using SEV-SNP attestation to approve workloads, a report depends on host firmware as well as the guest image; a later fix cannot make reports produced while the host was compromised trustworthy.