Infrastructure as a Service (IaaS) is an innovative and one of the significantly achieved developments in the cloud computing environment. Providing security to the cloud virtual machines and users’ data, are the greatest challenge of information system. So understanding the risks of the security and privacy in the cloud and developing efficient and effective solutions for it is really a difficult task. This model outlines the dynamics of both populations i.e. Exposed Virtual machine (EVM) and Infectious Virtual machine (IVM) in the cloud based upon the Predator-Prey Model. The proposed work would minimize the threats to the virtual machines in the cloud environment irrespective of the user's applications and security policy. It will basically ensure the degree of the security of virtual machines in a cloud environment which helps the cloud service providers to take the quick decisions and about the up gradation of the counter attack measurements.