One of the most dangerous assumptions in cloud computing is believing that once your workloads move to the cloud, security becomes entirely the cloud provider’s problem. In reality, every major cloud platform operates under a Shared Responsibility Model.
This framework clearly divides security duties between the Cloud Service Provider (CSP) and the Customer. Understanding where the provider’s responsibility ends and yours begins is essential to avoiding security breaches, compliance failures, and data exposure.
The Core Rule of Thumb
AWS popularized a simple mental model that applies across all cloud vendors:
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Security OF the Cloud: The provider is responsible for protecting the infrastructure that runs all the services offered in the cloud (hardware, physical data centers, networking, and core virtualization layers).
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Security IN the Cloud: The customer is responsible for everything they build, configure, or put into the cloud (data classification, identity management, OS patching, firewall configurations, and code).
How Responsibility Shifts by Service Model
The division of responsibility is dynamic—it shifts based on whether you deploy IaaS, PaaS, or SaaS solutions.
+--------------------------------------------------------------------------+
| SHARED RESPONSIBILITY SPECTRUM |
+--------------------------------------------------------------------------+
| On-Premises: CUSTOMER manages 100% of the stack |
| IaaS: PROVIDER manages Hardware/Virtualization; CUSTOMER manages OS+ |
| PaaS: PROVIDER manages OS & Runtime; CUSTOMER manages Code & Data |
| SaaS: PROVIDER manages Application; CUSTOMER manages Data & Access |
+--------------------------------------------------------------------------+
1. Infrastructure as a Service (IaaS)
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Examples: AWS EC2, Azure VMs, Google Compute Engine
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Customer Responsibility (High): You manage operating system patches, middleware, network configurations (security groups/firewalls), application software, and access permissions.
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Provider Responsibility: Physical data center security, server hardware, power/cooling, and host hypervisors.
2. Platform as a Service (PaaS)
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Examples: AWS Elastic Beanstalk, Azure App Service, Google App Engine
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Customer Responsibility (Medium): You manage application code, API integrations, data classification, and Identity and Access Management (IAM) configurations.
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Provider Responsibility: Operating system updates, runtime environments, database engine maintenance, and network infrastructure.
3. Software as a Service (SaaS)
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Examples: Microsoft 365, Google Workspace, Salesforce
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Customer Responsibility (Low): You manage user identity access, multi-factor authentication (MFA), device security, and data governance.
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Provider Responsibility: Application feature development, database management, underlying infrastructure, physical security, and system availability.
Shared Responsibility Across the Big Three: AWS, Azure, and GCP
While all three hyperscalers follow the same fundamental division, each uses distinct terminology to define the framework.
| Provider | Core Security Framework | Provider’s Focus | Customer’s Focus |
| AWS | AWS Shared Responsibility Model | Hardware, software, networking, facilities running AWS Cloud services. | Guest OS, network config, firewall, IAM, customer data. |
| Microsoft Azure | Shared Responsibility in the Cloud | Physical hosts, physical network, physical data center operations. | Information & data, devices, accounts & identities. |
| Google Cloud (GCP) | Shared Responsibility & Shared Fate | Infrastructure security, platform security, physical facilities. | Content, access policies, deployment configurations. |
GCP’s “Shared Fate” Model
Google Cloud takes the concept a step further with Shared Fate. Beyond simply drawing a line of responsibility, Google provides customers with pre-configured secure blueprints, automated risk management tools, and insurance protection partnerships to help customers satisfy their end of the security bargain.
Key Takeaways for Enterprise IT Teams
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Data and Identity Are ALWAYS Your Responsibility: Regardless of whether you use IaaS, PaaS, or SaaS, you retain 100% ownership and accountability for your data and user access credentials.
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Misconfigurations Are Customer Vulnerabilities: If an S3 bucket or Blob storage container is left publicly accessible, the provider did not fail—the customer failed to execute their half of the model.
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Automate Auditing: Use Cloud Security Posture Management (CSPM) tools to continuously monitor your configurations against recommended cloud benchmarks.