The Cloud Shared Responsibility Model is a framework that explains how security and operational responsibilities are divided between a cloud service provider and the organisation using its services. It establishes which aspects of cloud infrastructure the provider manages and which security controls remain the customer’s responsibility. The exact division depends on the cloud service model, the technologies involved and the provider’s contractual arrangements.
Cloud providers such as Microsoft Azure, Amazon Web Services (AWS) and Google Cloud manage substantial parts of the underlying infrastructure supporting their services. However, using cloud technology does not transfer every security obligation to the provider. Organisations generally remain responsible for managing their information, user identities, access permissions and relevant service configurations. Depending on the service model, they may also need to maintain operating systems, applications, network controls and backup arrangements.
For UK businesses, particularly financial services firms, legal practices and organisations processing sensitive information, understanding shared responsibility is essential for cybersecurity, IT governance and compliance readiness. Cloud services can reduce the burden of maintaining physical infrastructure, but security gaps may develop when businesses incorrectly assume that the provider manages controls that remain under customer responsibility.
Why the Cloud Shared Responsibility Model Is Important for Businesses
Cloud computing allows organisations to access sophisticated technology without maintaining all the physical infrastructure required to support it. Businesses can use hosted applications, deploy virtual servers and store information in cloud environments managed by specialist providers.
However, cloud adoption also changes how security responsibilities are allocated.
An organisation may assume that because its information is hosted by a major cloud provider, every aspect of that information is automatically protected. In practice, the provider may secure the underlying infrastructure while the customer remains responsible for controlling who can access the information and how it is shared.
The Cloud Shared Responsibility Model helps organisations understand these distinctions.
Key Benefits of Understanding Shared Responsibility Include:
- Clearer Security Accountability: Identifies which protective measures belong to the cloud provider and which remain with the customer.
- Reduced Configuration Risks: Helps organisations recognise security settings they must manage themselves.
- Stronger Data Protection: Clarifies responsibilities for information classification, access permissions and data handling.
- Improved Identity Security: Reinforces customer obligations concerning authentication and account management.
- Better Supplier Governance: Supports evaluation of cloud provider security commitments and service arrangements.
- More Effective Risk Management: Helps identify weaknesses caused by unclear or incorrectly allocated responsibilities.
- Improved Compliance Readiness: Provides a basis for documenting cloud security controls and accountability.
- Stronger Operational Resilience: Encourages businesses to understand backup, availability and recovery responsibilities.
For example, a legal practice may use Microsoft 365 to store client documents and manage professional correspondence.
Microsoft manages the underlying cloud service infrastructure, but the organisation must still establish appropriate user permissions, authentication controls and information sharing arrangements.
If a confidential document becomes accessible to an unauthorised user because of incorrect sharing permissions, the issue may arise from a customer-managed configuration rather than a failure of the cloud infrastructure.
Understanding this division helps businesses maintain appropriate oversight of services that are essential to their operations.
How the Cloud Shared Responsibility Model Works
The Cloud Shared Responsibility Model works by dividing security activities according to the type of cloud service being used.
The three principal service models are Infrastructure as a Service (IaaS), Platform as a Service (PaaS) and Software as a Service (SaaS).
Each model transfers different levels of infrastructure management responsibility to the cloud provider.
The more infrastructure and application management a provider handles, the fewer underlying technical components the customer usually needs to maintain directly. However, customer responsibilities for information governance and appropriate access controls remain important.
A Typical Shared Responsibility Assessment Includes:
- Identify Cloud Services: Document the cloud platforms, applications and infrastructure used by the organisation.
- Determine the Service Model: Establish whether each service is delivered through IaaS, PaaS, SaaS or a combination of models.
- Review Provider Responsibilities: Understand which infrastructure, platform and security activities the provider manages.
- Identify Customer Obligations: Determine which configurations, permissions, applications and information require customer oversight.
- Assess Existing Controls: Evaluate whether customer-managed responsibilities are being fulfilled effectively.
- Clarify Supplier Agreements: Review contractual arrangements, available security features and service commitments.
- Assign Internal Ownership: Establish responsibility for access management, monitoring, data protection and recovery activities.
- Monitor and Review: Reassess responsibilities as cloud services, configurations and business requirements change.
For example, a company running a virtual server through an IaaS service may be responsible for configuring and updating the guest operating system, maintaining deployed applications and controlling network access.
If the company instead uses a managed PaaS application hosting service, the provider usually assumes responsibility for more of the underlying platform, including the operating system and runtime environment.
With SaaS, the provider manages the application service and underlying infrastructure, while the customer remains responsible for activities such as user management, data governance and relevant security configurations.
These are general principles. Exact obligations should always be confirmed against the documentation and agreements for the specific service.
Key Components of the Cloud Shared Responsibility Model
The Cloud Shared Responsibility Model covers several security and operational areas. Understanding how these responsibilities change between service models is essential for establishing effective governance.
Infrastructure Security
Cloud providers are generally responsible for protecting the physical infrastructure used to deliver their services.
This includes data centres, physical servers, networking equipment and associated facilities.
Customers do not normally manage these underlying physical components when using public cloud services.
Identity and Access Management
Customers generally remain responsible for managing who can access their cloud accounts, applications and information.
Important controls include Multi-Factor Authentication, role-based permissions, privileged access management and employee account lifecycle procedures.
Cloud providers supply identity management capabilities, but organisations must configure and use them appropriately.
Application Security
Application security responsibilities depend on the service model.
With IaaS, customers typically manage the applications they deploy, including relevant security updates and configurations.
With PaaS, the provider manages more of the platform, but customers remain responsible for the applications and code they introduce.
With SaaS, the provider generally maintains the application service, while customers manage supported configurations, user access and appropriate information handling.
Data Protection and Governance
Organisations remain accountable for deciding what business information is stored in cloud services and how that information should be protected.
Relevant responsibilities include data classification, access control, retention policies, appropriate encryption decisions and compliance with applicable data protection requirements.
Cloud providers may supply technical protection capabilities, but customers must determine how to configure and use them.
Network and Configuration Security
Cloud network responsibilities vary according to the service model.
IaaS customers generally configure relevant virtual networks, firewalls and network security controls.
With managed platform services, some underlying network responsibilities transfer to the provider, while customers may still need to manage application-level access and exposure.
Backup and Recovery
Cloud providers manage the availability and resilience of their underlying services according to their contractual commitments.
However, customers must determine whether available backup, retention and restoration capabilities meet their business requirements.
Additional measures may be required to protect against accidental deletion, malicious changes or data loss scenarios not covered by standard service functionality.
Shared Responsibility Across Cloud Service Models
| Responsibility Area | IaaS | PaaS | SaaS |
| Physical Data Centre | Cloud provider | Cloud provider | Cloud provider |
| Physical Servers and Infrastructure | Cloud provider | Cloud provider | Cloud provider |
| Operating System Management | Customer | Cloud provider | Cloud provider |
| Application Management | Customer | Shared, depending on the service | Primarily cloud provider |
| Network Security Configuration | Primarily customer | Shared | Primarily cloud provider |
| User Accounts and Access Permissions | Customer | Customer | Customer |
| Data Governance and Protection Decisions | Customer | Customer | Customer |
| Business-Specific Backup and Recovery Requirements | Customer must assess and implement | Customer must assess and implement | Customer must assess and implement |
The table summarises typical arrangements rather than establishing universal contractual obligations.
The precise division of responsibility varies between providers, products and service features.
For example, a managed cloud service may offer built-in backup capabilities, but the organisation must still evaluate whether those capabilities satisfy its recovery objectives.
The model is therefore most useful when applied to specific services rather than treated as a general assumption about all cloud environments.
Common Cloud Shared Responsibility Risks and Challenges
Cloud security incidents frequently involve weaknesses in customer-managed configurations, identities or permissions.
One common problem is assuming that cloud providers automatically manage every aspect of cybersecurity because their infrastructure is professionally operated.
This misunderstanding can leave important controls without clearly assigned responsibility.
Common Shared Responsibility Challenges Include:
- Unclear Security Ownership: Organisations do not know which cloud controls they must configure or maintain.
- Weak Identity Protection: Accounts lack appropriate authentication requirements or access restrictions.
- Excessive Permissions: Employees, applications or external users receive more access than necessary.
- Insecure Cloud Configurations: Storage, services or administrative interfaces are exposed unintentionally.
- Unmanaged Applications: Business-critical software is deployed without appropriate security review.
- Incomplete Backup Arrangements: Organisations assume cloud hosting automatically provides all necessary recovery capabilities.
- Insufficient Monitoring: Relevant security events and unusual account activity are not reviewed.
- Poor Supplier Documentation: Important contractual and operational responsibilities remain unclear.
- Limited Visibility Across Multiple Clouds: Different providers and services introduce inconsistent control arrangements.
- Compliance Assumptions: Organisations incorrectly believe the provider’s certifications automatically establish customer compliance.
For example, a company may store confidential records in cloud storage and assume the provider is fully responsible for preventing unauthorised access.
However, if the business configures the storage resource with inappropriate public access permissions, sensitive information may become exposed despite the underlying infrastructure functioning securely.
Another common example involves ransomware and data recovery.
A SaaS provider may maintain resilient infrastructure and service-level backups, but those arrangements may not provide the same restoration options as a dedicated customer-controlled backup solution.
Businesses should verify which recovery scenarios are supported and whether additional protection is necessary.
For regulated organisations, cloud outsourcing also requires appropriate governance.
Using a well-established provider does not automatically transfer an organisation’s regulatory responsibilities. Businesses must continue to manage the risks associated with outsourced services and maintain suitable oversight.
The Cloud Shared Responsibility Model helps clarify operational security duties, but legal and contractual responsibilities must be assessed separately.
Best Practices for Managing Cloud Shared Responsibility
Effective cloud security begins with a clear understanding of which controls remain under the organisation’s management.
Businesses should establish a documented approach to cloud governance that considers service models, data sensitivity, operational requirements and relevant contractual obligations.
Best Practices for Cloud Shared Responsibility Include:
- Maintain a Cloud Service Inventory: Document cloud applications, infrastructure, providers and relevant business owners.
- Identify Responsibilities for Each Service: Review provider documentation and determine which controls remain customer-managed.
- Assign Clear Control Ownership: Establish who is responsible for security configurations, access management and monitoring.
- Strengthen Identity Security: Implement appropriate MFA, privileged access restrictions and regular permission reviews.
- Review Cloud Configurations: Evaluate storage access, external sharing, application permissions and other relevant security settings.
- Protect Sensitive Information: Apply appropriate data classification, retention and access controls.
- Assess Backup Requirements: Confirm whether existing cloud recovery capabilities satisfy business RTOs and RPOs.
- Monitor Security Activity: Review relevant logs, security alerts and changes to important configurations.
- Evaluate Cloud Suppliers: Understand contractual commitments, security certifications and relevant service limitations.
- Maintain Compliance Evidence: Record important configurations, assessments, security reviews and corrective actions.
- Review Responsibilities After Changes: Reassess control ownership when cloud services, suppliers or application architectures change.
- Integrate Cloud Risk With IT Governance: Include important cloud security concerns in wider risk management and operational resilience processes.
For example, a business using Microsoft 365 can maintain a cloud responsibility register covering user account administration, Multi-Factor Authentication, external document sharing, information retention and data recovery requirements.
Each control can be associated with a responsible owner, relevant configuration, review frequency and supporting evidence.
This makes it easier to identify gaps between what the provider delivers and what the organisation is expected to manage.
For London SMEs and regulated firms, a documented responsibility model can also improve communication between internal management, cloud providers, Managed Service Providers and compliance professionals.
An external IT provider may assist with customer-managed cloud controls, but the exact duties should be defined through appropriate service agreements.
Businesses should avoid assuming that purchasing managed IT services automatically transfers every cloud security responsibility to the provider.
The objective is to maintain clear accountability and ensure that important controls are implemented, monitored and reviewed consistently.
Conclusion: Why the Cloud Shared Responsibility Model Matters
The Cloud Shared Responsibility Model explains how security and operational responsibilities are divided between cloud providers and their customers. While cloud services can reduce the burden of maintaining physical infrastructure and platform components, organisations continue to hold important responsibilities for their information, identities, access controls and relevant configurations.
For London SMEs and regulated firms, understanding these responsibilities is essential for effective cybersecurity, data protection, supplier oversight and operational resilience. Security weaknesses often emerge when businesses assume that providers manage controls which remain within the customer’s scope. Clear documentation and regular reviews can help prevent these gaps.
A well-managed approach to shared responsibility allows organisations to take advantage of cloud technology while maintaining appropriate oversight of business risks. By identifying control ownership, evaluating provider commitments and verifying customer-managed safeguards, businesses can build more secure, accountable and resilient cloud environments.