SSRM Cloud Security Shared Responsibility Matrix: Mapping Obligations in Cloud Environments

Who Owns What in the Cloud: The SSRM Shared Responsibility Matrix

The SSRM cloud security shared responsibility matrix maps the division of security obligations between providers and customers across infrastructure layers. In cloud models, providers typically secure the physical data centers, network, and platform, while customers own application data, access controls, and configuration. Misunderstanding this split causes gaps that lead to breaches and compliance failures. This matrix clarifies where each party's duties lie so security teams can focus on what they actually control. Readers should treat it as a checklist to benchmark their environment and align documentation with real-world obligations.

How the SSRM Matrix Structures Cloud Security Duties

The SSRM framework divides responsibility into clear tiers based on service models. In IaaS, customers manage operating systems and applications, while providers cover hardware and physical site security. In PaaS, customers own data and access policies, while the platform layer is provider-controlled. In SaaS, the provider handles most technical controls, but customers remain responsible for user provisioning and data classification. The matrix becomes a living document that tracks these boundaries and helps auditors verify where controls are applied correctly.

What Providers Typically Secure

• Physical data centers and facility security
• Network infrastructure and perimeter controls
• Hypervisor and managed platform components
• Hardware encryption and device disposal
• Core compliance certifications and audits

What Customers Typically Secure

• Identity and access management configurations
• Data classification and retention policies
• Application-level controls and code security
• Endpoint protections for managed devices
• Logging and monitoring in customer namespaces

Why the SSRM Matrix Matters for Risk Management

Without clarity, teams assume someone else handles critical controls. The SSRM cloud security shared responsibility matrix removes ambiguity by naming the owner of each domain. It helps security leaders map controls to services, prioritize remediation, and prove due diligence during audits. It also supports incident response by clarifying whether an issue falls under the provider or customer domain, reducing finger-pointing and delays.

Identifying Gaps with the Matrix

Teams compare their environment against the matrix to find missing controls. A common gap is unencrypted data at rest in a customer-managed database while the provider offers native encryption but leaves it disabled. Another is overly broad access because no one enforced least privilege in the application layer. By using the SSRM framework, organizations document where these risks sit and assign accountability to close them systematically.

Aligning the Matrix with Compliance Requirements

Many frameworks reference shared responsibility explicitly, including ISO 27017 and ISO 27018. The SSRM cloud security shared responsibility matrix allows internal teams to map their controls to these standards and provide evidence that responsibilities are understood. Internal audit and GRC teams use it to show that both sides of the provider-customer relationship have defined security requirements, especially for regulated industries handling sensitive data in the cloud.

Demonstrating Ownership with the Matrix

Instead of relying on vague agreements, the matrix requires security teams to list control owners, service types, and enforcement methods. For example, customers may document that they use IAM policies to restrict access, while the provider offers network segmentation and physical controls. The SSRM matrix turns these statements into auditable artifacts that map to real controls and track implementation across cloud services.

Steps to Build and Maintain the SSRM Matrix

Security teams should start by documenting every cloud service and its model type. Then they list controls and assign each to either the provider or customer, based on standard definitions. They update it when services change, when new features launch, or when audit feedback identifies a missing responsibility. The matrix grows as the environment matures and becomes a reference for onboarding, training, and compliance programs.

Keeping the Matrix Current

Providers update their service offerings, which shifts the boundary of responsibility. A new managed database service may move encryption from customer to provider control. Conversely, a SaaS addition may increase customer duties around user access governance. Security teams must refresh the SSRM framework after each major change and validate it with internal and external auditors to ensure alignment.

Conclusion

The SSRM cloud security shared responsibility matrix gives organizations a structured way to understand and document where security responsibilities lie. It reduces ambiguity, improves compliance, and clarifies who owns each domain from infrastructure to application. By using it consistently, teams prevent gaps, support audits, and keep cloud environments secure over time.