This work examines the use of model checking techniques to verify system-level security properties of a collection of interacting virtual machines. Specifically, we examine how local access control policies implemented in individual virtual machines and a hypervisor can be shown to satisfy global access control constraints. The SAL model checker is used to model and verify a collection of stateful domains with protected resources and local MAC policies attempting to access needed resources from other domains. The model is described along with verification conditions. The need to control state-space explosion is motivated and techniques for writing theorems and limiting domains explored. Finally, analysis results are examined along with analysis complexity.

Cloud computing uses virtualization to lease small slices of large-scale datacenter facilities to individual paying customers. These multi-tenant environments, on which numerous large and popular web-based applications run today, are founded on the belief that the virtualization platform is sufficiently secure to prevent breaches of isolation between different users who are co-located on the same host. Hypervisors are believed to be trustworthy in this role because of their small size and narrow interfaces.