Virtualization is rapidly becoming a standard technology for businesses. The technology lets a single PC or server simultaneously run multiple operating systems or multiple sessions of a single OS. The approach is thus becoming a common way for users to optimize their hardware utilization by maximizing the number and kinds of jobs a single CPU can handle. Organizations now face the challenge of securing virtualized systems, which are vulnerable to the same threats as physical systems, including intrusions and malware. Virtualized systems cannot always be secured the same way as physical systems. Many virtualized systems can run on the same machine, but each one might need a different security level. Thus, security cannot simply be applied across the entire machine, as is the case with typical physical systems.