What is a Shared Responsibility Model?
The shared responsibility model is a fundamental concept in cloud computing that outlines the division of security responsibilities between the cloud provider and the customer. It acknowledges that security in the cloud is not solely the provider's concern, nor is it entirely the customer's burden. Instead, it's a collaborative effort where each party is responsible for specific aspects of security. Understanding this model is crucial for organisations migrating to or operating in the cloud, as it dictates who is accountable for protecting different layers of the cloud environment.
The model varies depending on the cloud service model being used (IaaS, PaaS, or SaaS), with the customer typically assuming more responsibility in IaaS and less in SaaS. The core principle remains consistent: the cloud provider secures the underlying infrastructure of the cloud, while the customer secures what they put in the cloud. This includes data, applications, operating systems, and access controls, depending on the service model.
Cloud Provider Responsibilities
Cloud providers are responsible for the security of the cloud itself. This encompasses the physical infrastructure, hardware, software, networking, and facilities that support the cloud services. Key areas of responsibility for the provider include:
Physical Security: Protecting data centres from physical threats, including unauthorised access, natural disasters, and power outages.
Infrastructure Security: Securing the hardware, software, and networking components that make up the cloud infrastructure. This includes patching vulnerabilities, implementing firewalls, and preventing denial-of-service attacks.
Virtualisation Security: Ensuring the security of the virtualisation layer, which isolates virtual machines and containers from each other.
Network Security: Protecting the network infrastructure from unauthorised access and malicious activity.
Compliance and Certifications: Maintaining compliance with relevant industry regulations and security standards, such as ISO 27001, SOC 2, and PCI DSS.
Essentially, the cloud provider is responsible for the security underneath the services they offer. They provide a secure foundation upon which customers can build and deploy their applications and store their data. However, this doesn't absolve the customer of their security responsibilities.
Customer Responsibilities
The customer is responsible for the security in the cloud. This means securing the data, applications, operating systems, and identities that they deploy and manage within the cloud environment. The specific responsibilities vary depending on the cloud service model, but generally include:
Data Security: Protecting data at rest and in transit, including encryption, access control, and data loss prevention.
Application Security: Securing applications from vulnerabilities, including code reviews, penetration testing, and web application firewalls.
Identity and Access Management (IAM): Controlling access to cloud resources and data through strong authentication, authorisation, and privilege management.
Operating System Security: Patching and hardening operating systems to prevent vulnerabilities and malware infections (primarily in IaaS).
Network Configuration: Configuring network security groups and firewalls to control network traffic and prevent unauthorised access (primarily in IaaS).
Compliance: Ensuring that their use of cloud services complies with relevant industry regulations and internal policies. Understanding our services can help you determine the best approach to compliance.
It's crucial for customers to understand their responsibilities and implement appropriate security controls to protect their assets in the cloud. Failure to do so can lead to data breaches, security incidents, and compliance violations. Learn more about Cyberinsights and how we can assist you with your cloud security needs.
Different Cloud Service Models (IaaS, PaaS, SaaS)
The shared responsibility model differs significantly depending on the cloud service model used:
Infrastructure as a Service (IaaS): In IaaS, the customer has the most responsibility. The provider manages the underlying infrastructure (servers, storage, networking), while the customer is responsible for the operating system, middleware, runtime, data, and applications. This model offers the most flexibility but also requires the most security expertise.
Provider: Physical infrastructure, virtualisation, networking.
Customer: Operating system, middleware, runtime, data, applications, IAM, network configuration.
Platform as a Service (PaaS): In PaaS, the provider manages the infrastructure, operating system, and middleware. The customer is responsible for the runtime, data, and applications. This model offers a balance between flexibility and ease of management.
Provider: Physical infrastructure, virtualisation, networking, operating system, middleware.
Customer: Runtime, data, applications, IAM.
Software as a Service (SaaS): In SaaS, the provider manages everything, including the infrastructure, operating system, middleware, runtime, data, and applications. The customer is primarily responsible for data security and user access. This model offers the least amount of control but also requires the least amount of security expertise. Many frequently asked questions relate to the division of responsibilities in SaaS models.
Provider: Physical infrastructure, virtualisation, networking, operating system, middleware, runtime, data, applications.
Customer: Data, IAM.
Here's a table summarising the responsibilities:
| Responsibility | IaaS | PaaS | SaaS |
| ----------------------- | --------- | --------- | --------- |
| Physical Infrastructure | Provider | Provider | Provider |
| Virtualisation | Provider | Provider | Provider |
| Networking | Provider | Provider | Provider |
| Operating System | Customer | Provider | Provider |
| Middleware | Customer | Provider | Provider |
| Runtime | Customer | Customer | Provider |
| Data | Customer | Customer | Customer |
| Applications | Customer | Customer | Provider |
| IAM | Customer | Customer | Customer |
Securing Your Data in the Cloud
Regardless of the cloud service model, securing your data in the cloud is paramount. Here are some best practices:
Encryption: Encrypt data at rest and in transit to protect it from unauthorised access. Use strong encryption algorithms and manage encryption keys securely.
Access Control: Implement strong access control policies to restrict access to data based on the principle of least privilege. Use multi-factor authentication (MFA) to enhance security.
Data Loss Prevention (DLP): Implement DLP tools to prevent sensitive data from leaving the cloud environment. Monitor data usage and detect potential data breaches.
Regular Backups: Back up data regularly to protect against data loss due to accidental deletion, hardware failure, or ransomware attacks. Store backups in a secure location.
Vulnerability Management: Regularly scan for vulnerabilities in applications and infrastructure and patch them promptly. Use automated vulnerability scanning tools to streamline the process.
Security Information and Event Management (SIEM): Implement a SIEM system to collect and analyse security logs from various sources. Use SIEM to detect and respond to security incidents in real-time.
Examples of Shared Responsibility in Action
Here are some concrete examples of how the shared responsibility model works in practice:
Example 1: Data Breach in IaaS: A company using IaaS experiences a data breach due to a misconfigured firewall. The cloud provider is responsible for the security of the underlying network infrastructure, but the customer is responsible for configuring the firewall correctly. In this case, the customer would be held responsible for the data breach.
Example 2: DDoS Attack in PaaS: A website hosted on PaaS is targeted by a distributed denial-of-service (DDoS) attack. The cloud provider is responsible for protecting the underlying infrastructure from DDoS attacks, including implementing mitigation measures. In this case, the cloud provider would be responsible for mitigating the attack.
- Example 3: Account Takeover in SaaS: A user's account in a SaaS application is compromised due to a weak password. The cloud provider is responsible for providing secure authentication mechanisms, but the customer is responsible for choosing a strong password and protecting their credentials. In this case, the customer would be held responsible for the account takeover.
Understanding the shared responsibility model is crucial for effectively managing cloud security. By clearly defining the roles and responsibilities of both the cloud provider and the customer, organisations can ensure that all aspects of their cloud environment are adequately protected. When choosing a provider, it's important to understand their security practices and how they align with your own security requirements.