What Is a Policy Engine?

A policy engine is a software component that allows an organization to define, manage, and enforce security policies or rules across its cloud environment. Administrators can create application-wide security policies, and developers can permit users to access data and resources from a centralized location. Any policy changes can be updated centrally for consistency and accuracy. A policy engine reduces the complexity of security management in large and distributed systems.

What are the benefits of a policy engine?

There are several key benefits that an organization can gain by implementing policy engines.

Fine-grained authorization

Fine-grained authorization refers to a security approach where permissions and access rights are assigned and managed with a high level of detail and precision. Organizations can take distinct conditions and attributes into account when authorizing access, allowing for very specific permissions. For example, rather than granting access to an entire database, it might allow a user to access only certain records or fields within a database.

Through creating fine-grained permissions, administrators can establish a comprehensive access control framework. This approach enhances security and gives administrators more control over policy enforcement.

Added flexibility

The flexibility of having a separate policy engine allows businesses to rapidly respond to any business operations changes or emerging security requirements. System administrators can manage changes without altering application code or settings. They can update or modify policies from one centralized location.

Policy engines enforce security policies without the need for continuous monitoring. They automatically apply conditional rules whenever a user makes a request. Automating the process improves security and minimizes the risk of human error.

Reduced security risk

Using a policy engine within an organization’s security framework helps to reduce the overall security risk. By adhering to the principle of least-privilege access, users are only granted access to enterprise resources that align with their roles. This decreases the possibility of unauthorized users accessing sensitive data.

Policy engines also include components that streamline logging related to policy enforcement. They add detailed information to a protected log whenever they grant or deny access. The log provides enhanced security while creating a traceable trail for auditing purposes. It further minimizes security risks by decreasing the time required for security incident response.

Scalability

Using a policy engine allows businesses to separate policy and server or application logic. They manage policies independently and apply them to other applications without coupling them. This approach leads to a more effective method to manage access requests, safeguard data, and protect network resources. The reusability that policy engines offer also allows businesses to reduce the effort of developing policies and scale policy management to dynamic environments at the same time.

What are the components of a policy engine?

A policy engine has several core components that allow it to function.

Policy repository

A policy repository (or policy store) can be a database, a file system, or any other storage system capable of holding the policy data. It stores policies and allows the engine to retrieve them efficiently. Policies are usually defined in formal language and specify the rules that determine access rights.

Policy administration point

A policy engine will also typically have a policy administration point (PAP) that allows administrators to edit, update, or delete policies from the repository. The PAP offers an interface that administrators can interact with to add or modify policies. They specify who is allowed to do what under which conditions.

Policy decision point

The policy decision point (PDP), or policy evaluator, is responsible for evaluating access requests against the policies stored in the policy repository. When a request is received, the PDP determines whether the request should be allowed or denied based on the applicable policies. In some circumstances, the policy evaluator will gather additional information from the policy information point (PIP).

Policy information point

The PIP is the source of additional information that might be needed by the PDP to make a decision. It stores other details about the user and environment—like device status, user roles, or location—to give more context to the request. The PIP retrieves and provides this information to the PDP during the decision-making process.

Policy enforcement point

The policy enforcement point (PEP) is the component that actually enforces the decisions made by the PDP. It monitors the point of access, such as a network gateway, application, or database, and either allows or denies access based on the PDP’s decision.

Audit and compliance logging

This component is responsible for recording decisions, changes to policies, and access attempts (both granted and denied). It is crucial for compliance, monitoring, and forensic purposes.

How do policy engines work?

The main function of a policy engine is to facilitate dynamic policy enforcement. A policy-enabled API gateway allows businesses to adopt, modify, and manage policies without the need for extensive code changes. Creating constraints and conditions is the first step to making a policy engine work. Systems engineers commonly use XACML (eXtensible Access Control Markup Language) to create these rules.

When a user initiates an access request to a database or sensitive information:

The request passes to the policy management component.
The policy evaluator uses rule-based logic and pattern-matching techniques to determine whether the request complies with the defined conditions.
If the policy evaluator grants access, the PEP module permits the operation and gives the user network access to the information.
If the user is not authorized, the PEP blocks the action.

In more complex systems, a context handler may be used to coordinate the interactions between the PEP, PDP, PIP, and PAP. It processes the requests from the PEP, collects the necessary information from the PIP, sends the request for decision to the PDP, and then returns the decision to the PEP.

Whether the policy engine determines approval or denial, it will log the requested access and its status alongside the time of request, outcome, and other relevant information.

How do you define policies in a policy engine?

Policy engines support a declarative language to define policies or rules. We give some examples below.

Cedar

Cedar is a flexible, extensible, and scalable policy-based access control language that helps developers express application permissions as policies. It supports authorization rules for any type of principal and resource, allows for role-based and attribute-based access control, and supports analysis through automated reasoning tools. Because Cedar policies are separate from application code, they can be independently authored, analyzed, audited, and even shared among multiple applications. Multiple policies can also be attached to a single resource. Once you specify fine-grained permissions as Cedar policies, your application authorizes access requests by calling the Cedar SDK’s authorization engine.

Rego

Rego is the policy language used by Open Policy Agent (OPA), a general-purpose policy engine recommended for the AWS environment. You can use Rego to draft policies and rules that exist separately from an application and can render authorization decisions without any application-specific logic. OPA also exposes a RESTful API to make retrieving authorization decisions simple and straightforward. To make an authorization decision, an application queries OPA with JSON input, and then OPA evaluates the input against the specified policies to return an access decision in JSON. OPA is also capable of importing external data that might be relevant in making an authorization decision.

How can AWS support your policy engine requirements?

Amazon Verified Permissions is a scalable permissions management and fine-grained authorization service for the applications that you build. With Verified Permissions, developers can build more secure applications faster by externalizing authorization and centralizing policy management. This helps you implement and enforce fine-grained authorization on resources within the applications you build and deploy, such as HR systems and banking applications.

With Verified Permissions, you can perform the following tasks:

Define a policy-based access model that describes the resources managed by your application and the actions (such as view, update, and share) that users can perform on those resources.
Provide application users with the ability to manage access to the resources managed. The application permits the specialist to view and update the records and store them in Verified Permissions.
Enforce those permissions.

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What Is a Policy Engine?