Describe the shared responsibility model


In organizations running only on-premises hardware and software, the organization is 100 percent responsible for implementing security and compliance. With cloud-based services, that responsibility is shared between the customer and the cloud provider.

The shared responsibility model identifies which security tasks are handled by the cloud provider, and which security tasks are handled by you, the customer. The responsibilities vary depending on where the workload is hosted:

  • Software as a Service (SaaS)
  • Platform as a Service (PaaS)
  • Infrastructure as a Service (IaaS)
  • On-premises datacenter

The shared responsibility model makes responsibilities clear. When organizations move to the cloud, some responsibilities transfer to the cloud provider and some to the customer organization.

The following diagram illustrates the areas of responsibility between the customer and the cloud provider, according to where data is held.

The Shared responsibility model responsibilities by type.

  • On-premises datacenters. In an on-premises datacenter, you have responsibility for everything from physical security to encrypting sensitive data.

  • Infrastructure as a Service (IaaS). Of all cloud services, IaaS requires the most management by the cloud customer. With IaaS, you're using the cloud provider’s computing infrastructure. The cloud customer isn't responsible for the physical components, such as computers, the network, or the physical security of the datacenter. However, the cloud customer still has responsibility for software components running on that computing infrastructure such as operating systems, network controls, applications, and protecting data.

  • Platform as a Service (PaaS). PaaS provides an environment for building, testing, and deploying software applications. The goal of PaaS is to help you create an application quickly without managing the underlying infrastructure. With PaaS, the cloud provider manages the hardware and operating systems, and the customer is responsible for applications and data.

  • Software as a Service (SaaS). SaaS is hosted and managed by the cloud provider, for the customer. It's usually licensed through a monthly or annual subscription. Microsoft 365, Skype, and Dynamics CRM Online are all examples of SaaS software. SaaS requires the least amount of management by the cloud customer. The cloud provider is responsible for managing everything except data, devices, accounts, and identities.

For all cloud deployment types you, the cloud customer, own your data and identities. You're responsible for protecting the security of your data and identities, and on-premises resources including mobile devices, PCs, printers, and more.

In summary, responsibilities always retained by the customer organization include:

  • Information and data
  • Devices (mobile and PCs)
  • Accounts and identities

The benefit of the shared responsibility model is that organizations are clear about their responsibilities, and those of the cloud provider.