EqualVisor: Providing Memory Protection in an Untrusted Commodity Hypervisor

In cloud computing, hypervisor is the all-powerful software running in the highest privilege layer, thus attackers who compromise a hypervisor may jeopardize the whole cloud, especially cause memory corruption of any sensitive workloads within the cloud. In this paper, we propose a novel architecture and approach to provide memory protection from an untrusted hypervisor on current x86 platforms. Unlike previous approaches such as nested virtualization, we do not place another higher privilege TCB below the hypervisor. Instead, our approach introduces a properly isolated tiny TCB running in the same privilege level and the same address space with the hypervisor, and uses this TCB to intercept and validate hypervisor´s privilege actions for memory protection. In this way, we can enforce further memory security policies only relying on the TCB even if the hypervisor is fully compromised.