A company subscribes to a SaaS human resources application hosted by an external provider. The provider is responsible for maintaining the physical data centers, network infrastructure, and the underlying application software. The company is responsible for managing user accounts, configuring user permissions, and classifying the data they upload. Which security model does this arrangement primarily describe?
The shared responsibility model correctly defines the split of security tasks between the cloud provider and the customer based on the service model (IaaS, PaaS, SaaS). In this SaaS example, the provider handles infrastructure, and the customer handles data and access.
Why this answer
The scenario explicitly describes a division of security responsibilities between the SaaS provider and the customer. The provider handles physical security, network infrastructure, and application software (security *of* the cloud), while the company manages user accounts, permissions, and data classification (security *in* the cloud). This is the core definition of the shared responsibility model, which is foundational to cloud computing and directly tested in SC-900.
Exam trap
The trap here is that candidates confuse the shared responsibility model with defense in depth or Zero Trust, because all three involve 'security layers' or 'trust boundaries,' but only the shared responsibility model specifically defines the split of security obligations between a cloud provider and a customer.
Why the other options are wrong
The question describes a division of security responsibilities between the provider and the company, which is the essence of the shared responsibility model, not defense in depth. Defense in depth refers to multiple layers of security controls, not the allocation of responsibilities.
The question describes a clear division of security responsibilities between the provider and the company, which is the essence of the shared responsibility model. Zero Trust is a security framework that assumes no implicit trust and requires continuous verification, but it does not specifically address the division of responsibilities for different components of a cloud service.
The CIA triad (Confidentiality, Integrity, Availability) is a security model for guiding information security policies, but it does not describe the division of responsibilities between a cloud provider and customer. The question specifically asks about the arrangement of responsibilities, which is the shared responsibility model.