Cross-VM Cache Side Channel Attacks in Cloud: A Survey

In cloud-computing, virtual machines(VMs)of different tenants might be scheduled to run on the same physical machine, namely VMs co-residency. Co-resident VMs would share the underlying computing resources of the physical machine, relying on the virtual machine monitor to allocate and schedule system resources. Cross-domain sharing of underlying computing resources, albeit improving the utilization efficiency of available resources extremely, poses a serious threat to users' privacy concerns. A malicious VM could break the isolation mechanism and extract private information from other co-resident VMs, simply by probing the responses of shared resources and establishing a special leakage model. This attack pattern described above is usually called side-channel attacks. This paper deeply studied the mechanism and implementation of cross-VM cache side-channel attacks, and summarized its research status and advances. First, the essential cause of cache-based side-channel information leakage is analyzed and summarized. Next, the origin and research progress of cross-VM cache side-channel attacks are reviewed, the differences and relations between classic cache side-channel attacks and cross-VM cache side-channel attacks are discussed, followed by presentation of the universal model of access-driven cross-VM cache side-channel attacks. Then, the related issues of VMs co-residency and the latest mainstream methods for cross-VM cache-based side-channel information probing are categorized and expounded in detail. Finally, the current problems existing in the research and the future research directions of this field are presented.