The cloud computing model should drive and potentially apply for the design and development of the next generation of adaptive security systems. This essay shows some conceptual ideas and directions based on systems engineering methods and architecting principles. The new cloud-based system security model should be directed to the definition of a cloud infrastructure, and related security services can be available as “services in the cloud” through a provider in a pervasive environment. Rittinghouse and Ransome (2010) have defined the concept of Security-as-a-Service, which can be achieved by collecting service security requirements mainly through an Enterprise Architecture approach and specifying the set of services that are needed for an organization viewed as an enterprise. By applying cloud concepts, these services can be dynamically adapted to the organization’s security requirements and practices.