Outlier: Enabling Effective Measurement of Hypervisor Code Integrity With Group Detection

Virtualization brings the benefits of utilization and scalability to the multi-tenant cloud platforms. However, the hypervisor, as one of the foundations in virtualization, is challenging to survive under various malicious attacks due to its large attack surface. This article presents a novel group detection framework for the hypervisor code integrity, called Outlier. In an Outlier group, each host contains two parts. One is a distributed detection protocol, called Co-protocol, and the other is a detection interface, called Checker. The Co-protocol constructs trust for the integrity detection within an Outlier group. With the Co-protocol, each Checker conducts reliable integrity detection on the hypervisor code, and then the potential 'outlier' host is perceived. We implement our Outlier prototype on the Xen hypervisor and evaluate its overhead. Experiments show that the introduction of the Outlier has few impacts on the performance of the virtualized systems.