Epyc Fail? Researchers Say They Can Defeat AMD’s Virtual Machine Encryption

German researchers reckon they have devised a method to thwart the security mechanisms AMD's Epyc server chips use to automatically encrypt virtual machines in memory.

So much so, they said they can exfiltrate plaintext data from an encrypted guest via a hijacked hypervisor and simple HTTP requests to a web server running in a second guest on the same machine.

AMD's data-center processors, as well as its Ryzen Pro line, support what's called Secure Encrypted Virtualization. This decrypts and encrypts virtual machines on the fly while stored in RAM so that the host operating system, hypervisor, and any malware on the host computer, cannot snoop on protected VMs. Each virtual machine is assigned an address space ID which is linked to a cryptographic key to cipher and decipher data as it moves between memory and the CPU cores. The key never leaves the system-on-chip, and each VM gets its own key.