Cloud Computing: How the Shared Responsibility Model Varies in IaaS, PaaS, and SaaS

The shared responsibility model in cloud computing outlines the division of security and compliance responsibilities between a cloud service provider (CSP) and the customer. While the CSP manages certain aspects of the infrastructure and services, customers are responsible for managing others, depending on the chosen service model: Infrastructure as a Service (IaaS), Platform as a Service (PaaS), or Software as a Service (SaaS). Here's how these responsibilities differ across the models:

1. Infrastructure as a Service (IaaS):

• Provider's Responsibility:

  • Physical infrastructure (data centers, servers, networking, storage).

  • Virtualization layer (ensuring hypervisors and host OS are secure).

• Customer's Responsibility:

  • Operating systems, middleware, runtime environments.

  • Data, applications, user access management.

  • Configuring security measures like firewalls and network settings.

Example: Services like Amazon EC2 or Microsoft Azure Virtual Machines.

2. Platform as a Service (PaaS):

• Provider's Responsibility:

  • Everything included in IaaS, plus operating systems, middleware, and runtime environments.

  • Built-in tools and frameworks for application development.

• Customer's Responsibility:

  • Application code and configurations.

  • Securing and managing their data.

  • User identity and access management.

Example: Services like Google App Engine or Azure App Services.

3. Software as a Service (SaaS):

• Provider's Responsibility:

  • Entire stack, including infrastructure, platforms, applications, and runtime.

  • Managing application security, updates, and maintenance.

• Customer's Responsibility:

  • Managing data usage within the application.

  • Configuring user permissions and access settings.

Example: Services like Microsoft 365 or Salesforce.

Key Takeaway:

As you move from IaaS to PaaS to SaaS, the CSP takes on increasing responsibilities. While IaaS offers flexibility with more customer control, SaaS provides convenience with minimal customer responsibility. The model chosen depends on the balance between control, flexibility, and operational overhead that best suits your needs.