In today's data centers, IT often virtualizes new applications and workloads by default. Virtualization is the norm; deploying a physical server is the exception. The technology is mature and enterprise adoption is high, yet information security does not have a significant focus on virtual security. Given the converged nature of virtual environments, security incidents can result in significant damage; therefore, it is critical that security professionals redouble their efforts and make securing their virtual infrastructure a priority. This guide describes the security challenges within virtualized environments and shows how to apply the concepts of Forrester's Zero Trust Model of information security to secure the virtual environment effectively.