Virtual Machine Isolation

The popularity and widespread adoption of cloud computing has resulted in extensified and intensive use of virtualization technology. Virtualization technology allows the sharing of the same physical resources among several users. This enables the consolidation of servers and a multitude of user machines into a very small set of physical servers, by replacing the physical machines with virtual machines, running on the same physical servers. Consequently, several users work on and store their data in the same physical platform. A software layer is used to enable the sharing of hardware between the different users. Understandably, this leads to apprehensions about the security of their data and working environment for the users, as these are situated only one software layer apart from those belonging to the other users. Centralized storage and centralized computing thus naturally raise the question of security of user’s data, and motivate studies on how data security could possibly be compromised. This article surveys the security concerns in virtualization technology. It includes a study of different attacks in the context of virtualization, and logically organizes them in different categories. Where available, the patches to the attacks are also included in the survey. A special focus of the survey is on hardware limitations to support virtualization, and the conclusion drawn is that hardware limitations of different types are the root cause of most of the security issues.