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> Something like speculative side channel attacks would still speculate on the unencrypted memory right? This wouldn't prevent a Spectre attack or similar cach
by theevilsharpie 6y ago
> Something like speculative side channel attacks would still speculate on the unencrypted memory right?
This wouldn't prevent a Spectre attack or similar cache-based attack, as the memory would be decrypted at that point. However, it would mitigate attacks like Meltdown or Rowhammer.
- eloff 6y agoI don't see how it protects against meltdown, wouldn't the memory still get decrypted by the escalated access? Edit: If each VM has it's own key, then they couldn't read each other's memory with meltdown. I think that must be the angle.
- theevilsharpie 6y ago> I don't see how it protects against meltdown, wouldn't the memory still get decrypted by the escalated access? No. A particular VM's memory is decrypted by that VM's key. Assuming that AMD's CPUs were vulnerable to a hypothetical attack similar to Meltdown, either a VM or a guest would be able to dump the machine's memory, but the memory contents belonging to other VMs would be encrypted and unintelligible.
- eloff 6y agoI think my edit and your comment passed each other on the wire. That makes sense, it gives hardware protection from privilege escalation between VMs on the same host. Be it through a hardware exploit or hypervisor vulnerability.