The use of server virtualization has been growing steadily, but many enterprises still are reluctant to migrate critical workloads to such infrastructures. One key inhibitor is the complexity of correctly configuring virtualized infrastructures, and in particular, of isolating workloads or subscribers across all potentially shared physical and virtual resources. Imagine analyzing systems with half a dozen virtualization platforms, thousands of virtual machines and hundreds of thousands of inter-resource connections by hand: large topologies demand tool support. We study the automated information flow analysis of heterogeneous virtualized infrastructures. We propose an analysis system that performs a static information flow analysis based on graph traversal. The system discovers the actual configurations of diverse virtualization environments and unifies them in a graph representation. It computes the transitive closure of information flow and isolation rules over the graph and di...