Direct answer first: In public cloud deployments, responsibility for the security of the hardware and underlying infrastructure sits with the cloud service provider (CSP). The customer shares responsibility for security of anything they deploy on top of that infrastructure, such as data, applications, configurations, and access controls. Context and nuances
- Shared responsibility model: The CSP secures the physical hardware, data centers, networking, virtualization, and the foundational cloud services themselves. Customers are responsible for securing their own data and workloads that run on the cloud, including operating systems (if any), application security, encryption, identity and access management, and configuring security controls for their environment. This division can vary by service model (IaaS vs PaaS vs SaaS) but hardware/physical infrastructure security remains CSP's at the foundational level.
- Common boundaries:
- Infrastructure and hardware security: CSP is responsible for securing the physical facilities, hardware, and the infrastructure stack that underpins the cloud services.
* Virtualization and platform services: CSP handles the virtualization layer and core platform services; customers manage what runs on top of them.
* Data and workloads: Customers own the security of their data, access controls, configuration, and application-level protections.
- Practical implications:
- Misconfigurations or weak access controls on the customer side are often the source of security incidents, even though the underlying hardware is CSP-managed. Proper configuration, patching, encryption, and key management are typically customer responsibilities depending on the service model.
* Vendors emphasize that understanding and adhering to the shared responsibility model is critical to achieving a secure cloud posture.
If you’d like, I can tailor this to a specific public cloud provider (AWS, Azure, Google Cloud) and service model (IaaS, PaaS, SaaS), with concrete examples of who is responsible for which components in each case.
