📖 What is Shared Responsibility Model?
Shared Responsibility Model is a cloud security framework that delineates which security tasks are handled by the cloud service provider (CSP) and which are the responsibility of the customer. The division of duties varies depending on the service model (IaaS, PaaS, or SaaS).
"Always identify the "line of demarcation." In IaaS, the customer manages the OS; in SaaS, the provider manages almost the entire stack."
📚 Certification: CompTIA Advanced Security Practitioner+ (CAS-004)
🔑 What are the Key Concepts of Shared Responsibility Model?
- ▸ In IaaS, the customer maintains control over the OS, middleware, and applications, while the provider secures the physical hardware, virtualization layer, and networking.
- ▸ PaaS shifts the OS and runtime management to the provider, leaving the customer responsible for securing the deployed applications and the data they process.
- ▸ SaaS minimizes customer responsibility to data management and identity access, as the provider manages the entire software stack from the hardware up to the app.
- ▸ The 'line of demarcation' is the critical boundary defining where the CSP's security obligations end and the customer's operational security responsibilities begin.
- ▸ Regardless of the service model, the customer always retains responsibility for identity and access management (IAM) and the classification and protection of their data.
🎯 How does Shared Responsibility Model appear on the CAS-004 Exam?
You may be asked to determine who is responsible for patching a virtual machine's operating system in an IaaS environment versus a PaaS environment to test your knowledge of demarcation.
A scenario might describe a data leak caused by an open cloud storage bucket; you must identify that the customer is responsible for the configuration and access policies, not the provider.
Expect questions where you must identify the correct evidence, such as a SOC 2 report, to prove the CSP's compliance with physical security controls during a high-level regulatory audit.
❓ Frequently Asked Questions
Does the Shared Responsibility Model eliminate the need for the customer to perform their own security audits?
No. While the CSP provides reports for the infrastructure, the customer must still audit their own configurations, IAM policies, and application-level security to ensure the entire environment remains compliant.
Who is responsible for network security in a cloud environment?
It is shared. The CSP secures the physical network and virtualization layer, but the customer is responsible for configuring virtual firewalls, security groups, and network access control lists.