Major flaw in AMD's 'secure' VM tech lets rogue cloud hosts steal secrets

Researchers at ETH Zurich have disclosed two serious attacks—Mior and Skyfall—that break the confidentiality guarantees of AMD's SEV-SNP technology, which is designed to keep cloud operators from reading data inside encrypted virtual machines. Both attacks require control of the server's hypervisor, and Mior additionally needs control of the BIOS and a PCIe device like a graphics card. They allow a malicious host to read and modify VM memory and even forge attestation reports that are supposed to verify a VM's integrity.

For engineers and cloud customers relying on AMD EPYC servers for confidential computing, this means that the hardware-based isolation SEV-SNP promises can be completely bypassed under certain conditions. AMD has released firmware and microcode patches dated August 12, with platform firmware updates from server makers expected in November and December. The takeaway: even hardware-enforced memory encryption isn't bulletproof if the underlying initialization process can be tampered with during boot.