With next-generation technologies such as dynamic authorization and fine-grained access control on the rise, it is important to understand the different frameworks to ensure organizations are using the best method for their needs. In this article, we will be covering the relationship between Policy Based Access Control (PBAC) and Attribute Based Access Control (ABAC), along with how PBAC can be used to implement ABAC and extend Role-Based Access Control (RBAC).
Attribute-Based Access Control (ABAC) and Policy-Based Access Control (PBAC) are complementary security models that can work together to provide a highly flexible, scalable, and dynamic approach to managing access in modern IT environments.
Policy-Based Access Control (PBAC)
PBAC, on the other hand, is a broader framework that focuses on policies to govern access control decisions. A PBAC system typically defines policies that specify the rules for granting or denying access to resources. These policies are often centralized and enforce access rules across an entire organization.
PBAC is flexible in that:
- It allows administrators to define access policies that can span roles, users, resources, environments, and actions.
- Policies can be defined for specific scenarios, such as role-based, attribute-based, or even context-based access control.
Attribute-Based Access Control (ABAC)
ABAC is an access control model that uses attributes (or characteristics) to define access policies. These attributes can apply to both users (e.g., job title, department, security clearance), resources (e.g., data classification, resource type), actions (e.g., read, write), and environmental factors (e.g., time of day, location).
In ABAC:
- Access decisions are based on if-then rules that evaluate the combination of these attributes.
- A policy might look like: “Allow access to financial data only if the user’s department is ‘Finance’ and they are accessing from an organization-approved device.”
- ABAC provides very fine-grained control and is highly adaptable to dynamic environments.
How ABAC and PBAC Fit Together
ABAC and PBAC can work together in a complementary way, where ABAC defines access decisions based on attributes, and PBAC is the overarching framework that uses these attributes (along with other factors) to manage and enforce policies for access control. In this sense, ABAC can be seen as a component of PBAC. Let’s see how they complement each other:
Policy Formulation in PBAC:
- In a PBAC system, administrators define high-level access policies. These policies are flexible and can be based on a range of factors such as roles, attributes, environmental context, and actions.
- Within PBAC, ABAC can be used to define the attributes that are evaluated in these policies.
- For example, PBAC might define a policy like: “Grant access to financial records if the user’s department is ‘Finance’ (ABAC attribute) and the access request occurs within business hours (ABAC context).”
Granularity in Access Control:
- ABAC provides granular control over specific attributes (like user, resource, and environment) that are often needed for a dynamic and context-sensitive security model.
- PBAC can integrate these fine-grained ABAC rules within broader policy structures, allowing organizations to manage access in a more structured and centralized way, while maintaining the flexibility that ABAC offers.
Centralized Management in PBAC with ABAC Flexibility:
- PBAC provides a centralized platform for managing access control policies across an organization, and by using ABAC attributes, it can enforce detailed, context-aware rules. This ensures that the organization maintains both flexibility and scalability.
- For example, in PBAC, administrators might set high-level access policies (e.g., allow all finance employees access to financial data) but use ABAC rules (e.g., only allow access to this data if the user is using a company-approved device) for more granular control.
Adaptability:
- PBAC and ABAC together make systems more adaptable to dynamic environments. If a user’s department changes or if a new regulation requires more stringent access controls (e.g., stricter rules for accessing sensitive data), these changes can be implemented within the PBAC framework, while ABAC ensures that the attribute-based rules are enforced dynamically without requiring major updates to the entire access control structure.
Combining Context and Attributes:
- One of the most powerful features of ABAC is its ability to evaluate contextual factors (e.g., time of day, location of access request). PBAC can integrate these contextual factors into a comprehensive access control policy, ensuring that access to data or resources is granted only under appropriate conditions.
Steps to Implement PBAC with ABAC
- Define Policies Based on Attributes:
- Create policies that define the conditions under which a user can access a resource. For example:
- Only users from the “HR” department can access payroll information.
- A user must have a “manager” role to approve financial transactions.
- The policies are typically written in a human-readable format or through policy management tools.
- Create policies that define the conditions under which a user can access a resource. For example:
- Map Attributes to Policy Conditions:
- Use attributes in policy conditions. For example, an access policy can check if the user’s department attribute matches the required department for a particular resource.
- You can incorporate more complex logic into policies, like checking if the time of access is within business hours or if the resource classification matches the user’s clearance level.
- Use a Policy Engine:
- Implement or use an existing Policy Decision Point (PDP) that evaluates the policies based on the attributes of the user, resource, action, and environment.
- The PDP takes in requests and determines if access should be granted based on the defined policies.
- Manage and Enforce Access:
- Once the policies are in place, PBAC allows the centralized management of access control decisions.
- You can also define automated processes to dynamically adjust policies as the organization’s needs or security requirements change.
Example of PBAC with ABAC
Imagine an organization that needs to control access to sensitive customer data. The PBAC system might define a policy that requires specific conditions to be met before granting access, while ABAC defines the actual attributes involved in evaluating these conditions.
- PBAC Policy: “Only users in the ‘Customer Support’ department can access customer data, but only if they are accessing the data during working hours and from a company-approved device.”
- ABAC Attributes:
- User’s department (e.g., “Customer Support”)
- Time of access (e.g., working hours)
- Device type (e.g., company-approved)
- ABAC Attributes:
In this case, the PBAC system centralizes the overall policy and workflow, while ABAC provides the dynamic, attribute-based criteria that the policy evaluates to decide access.
Benefits of Combining ABAC and PBAC
- Flexibility and Granularity: ABAC offers the flexibility to create complex, attribute-based policies, while PBAC helps in centralizing and managing those policies.
- Scalability: PBAC provides scalability by managing access control at an organizational level, whereas ABAC can dynamically adjust to specific user attributes.
- Fine-Grained Control: By combining ABAC’s attribute-based logic with PBAC’s policy management, you get precise, context-aware control over access to resources.
Conclusion
ABAC and PBAC fit together in a way that ABAC provides the fine-grained, dynamic decision-making capability based on user, resource, and contextual attributes, while PBAC offers a centralized platform for creating and managing complex access control policies. Together, they allow for a flexible, scalable, and adaptable access control model that can evolve with changing organizational needs and security requirements.
In summary:
- ABAC defines what attributes are needed for access decisions.
- PBAC defines how those attributes are used within broader access control policies.
This combined approach results in a security system that is both dynamic and comprehensive, capable of adapting to a wide range of access scenarios while maintaining tight control over who can access what, when, and how.
