An anonymous reader writes from a report via BleepingComputer: The security protocol that governs how virtual machines share data on a host system powered by AMD Zen processors has been found to be insecure, at least in theory, according to two German researchers. The technology, called Secure Encrypted Virtualization (SEV), is designed to encrypt parts of the memory shared by different virtual machines on cloud servers. AMD, who plans to ship SEV with its upcoming line of Zen processors, has published the technical documentation for the SEV technology this past April. The German researchers have analyzed the design of SEV, using this public documentation, and said they managed to identify three attack channels, which work, at least in theory. [In a technical paper released over the past weekend, the researchers described their attacks:] “We show how a malicious hypervisor can force the guest to perform arbitrary read and write operations on protected memory. We describe how to completely disable any SEV memory protection configured by the tenant. We implement a replay attack that uses captured login data to gain access to the target system by solely exploiting resource management features of a hypervisor.” AMD is scheduled to ship SEV with the Zen processor line in the first quarter of 2017. Read more of this story at Slashdot.