Cloud service models

The cloud has three common service models, all of which approach security differently. These were discussed briefly in Chapter 9, Incident Response on Multiple Platforms, but as a refresher, these models consist of:

• Software as a Service (SaaS): The vendor provides all resources on the cloud including the apps used by the client. Furthermore, the vendor controls the security aspects of the apps.
• Platform as a Service (PaaS): The vendor provides a complete runtime environment, which can be composed of storage, servers, and network bandwidth, that can be used to deploy anything from simple, cloud-based apps to sophisticated, cloud-enabled enterprise applications. The vendor manages everything, but you need to manage the applications and services that you develop. PaaS allows you to avoid buying and managing software licenses, underlying application infrastructure and middleware, container orchestrators, development tools, and other resources.
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