New Spectre-based CPU vulnerability allows guests to steal sensitive data from the cloud

Meltdown and Spectre.

• ETH Zurich researchers found a new Spectre-BTI attack called VMSCAPE that lets a VM steal host data
• It affects cloud setups using KVM/QEMU on AMD and Intel CPUs, bypassing existing defenses
• They propose flushing the branch predictor on VMEXIT as a low-cost fix

If Ghostbusters taught us anything, it’s that spectres are notoriously difficult to get rid of.