OAuth 2.0 Scopes: How They Work

You all must already be familiar with the ins and outs of the OAuth framework by now, but what are OAuth Scopes? In this detailed blog post, we’ll dive into the specifics of these crucial components.

What are OAuth Scopes? 

OAuth scopes are mechanisms used in the OAuth 2.0 framework to limit an application’s access to a user’s account. They provide a way to grant limited access to resources, data, or functionalities without sharing full control.

OAuth scopes act as permissions that can be asked by the client, granted by the user, and enforced by the server. Each scope represents a specific action the app can perform, such as reading emails, updating profile information, or managing files. By defining these scopes, it allows the user to control what information the application can access and what actions it can perform.

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Role and Purpose of OAuth Scopes in the OAuth Framework

OAuth scopes play a pivotal role in ensuring security and privacy in the OAuth framework. They provide a layer of protection by ensuring that the client applications only have access to the necessary resources, minimizing the risk of potential data breaches.

Defining the scopes allows the server to issue tokens with a specific set of permissions. These tokens can be used by the client applications to access resources. Each token is associated with a set of scopes, which determines what resources the token can access and what actions it can perform.

The purpose of OAuth scopes extends beyond just security. It also provides a way to manage the user’s experience. By limiting the application’s access to only necessary resources, it can prevent unnecessary data collection, thereby enhancing the user’s trust in the application.

Related content: Read our guide to OAuth flow

Examples of OAuth Scopes 

OAuth scopes can be as simple or complex as needed, depending on the application’s requirements. For instance, an application that allows users to manage their email account might have scopes such as ‘read-emails’, ‘send-emails’, and ‘delete-emails’. Each of these scopes represents a specific action the application can perform.

In a more complex scenario, an application that interacts with a user’s social media account might have scopes such as ‘read-posts’, ‘write-posts’, ‘read-friends-list’, ‘manage-photos’, etc. These scopes not only define what actions the application can perform but also what data it can access.

How OAuth Scopes Work 

In the OAuth protocol, scopes are defined by the resource server. The server determines what scopes are valid and what each scope represents. The scopes can be defined in the form of strings that represent a specific action or resource.

When the client wants to access a resource, it sends a request to the server, specifying the scopes it requires. This is done through the “scope” parameter in the request. The client can request multiple scopes by separating them with a space.

The server then evaluates the request and determines whether to grant the requested scopes. If the user approves, the server issues a token with the granted scopes. The token is then used by the client to access the resources.

For example, in the example below, an OAuth scope is defined on a specific cloud storage volume. If the user has access to read data from the volume, OAuth grants access.

OAuth Scopes and User Consent 

One of the key aspects of OAuth scopes is user consent. When a client requests access to a user’s resources, the user needs to give their consent. This is where OAuth scopes come in.

When the user is asked for their consent, they are presented with a list of scopes that the client has requested. The user can then review these scopes and decide whether to grant the requested permissions. This transparency enhances user trust, as they have full control over what the application can access.

How to Implement of OAuth Scopes 

Here are the main steps you should take when implementing OAuth scopes in your application.

1. Clearly Define and Document Available Scopes

The first step in effectively implementing OAuth scopes is to clearly define and document the available scopes. Each scope should have a specific, understandable purpose. For example, a “read_profile” scope could allow an application to access a user’s profile information, but not their private messages or other data.

Once you’ve defined your scopes, it’s crucial to document them. This serves two purposes. First, it helps your development team understand what each scope does, ensuring they use them correctly. Secondly, it provides valuable information to users, allowing them to make informed decisions about what permissions to grant to your application.

Clarity and transparency are key. Users should not have to guess what a scope means or does. If a user doesn’t understand what they’re granting access to, they’re likely to deny the request or, worse, grant it without fully understanding the implications.

2. Limit Scope Permissions Based on Application Type and Trust Level

Not all applications should have access to all scopes. The type of application and its trust level should dictate what scopes it can request. For instance, a trusted internal application might have access to a wider range of scopes than a third-party app.

Consider implementing a system that categorizes applications based on their type and trust level. This system would then dictate what scopes an application can request. This adds an extra layer of security, reducing the potential damage if an application is compromised. It also helps users feel more comfortable granting permissions, knowing that applications can’t request more access than they need or should have.

3. Request Minimum Scopes Necessary for Application Function

Just as you should limit what scopes an application can request based on its type and trust level, you should also limit what scopes an application does request. Each application should only request the minimum scopes necessary for its function.

For example, a photo editing app may need access to a user’s photos, but it likely doesn’t need access to their email or ability to post updates on their behalf. By only requesting the necessary scopes, you minimize the potential damage if the access token is compromised. You also improve user trust, as users are more likely to grant permissions if they see that an application only requests what it needs.

4. Use Scopes in Combination with Other Access Control Measures

While OAuth scopes are a powerful tool for controlling application access, they should not be the only tool you use. Consider using scopes in combination with other access control measures for robust security.

For instance, you might use scopes in conjunction with roles. Roles define what actions a user can perform, while scopes define what an application can do on behalf of a user. Combining these two can provide a more granular control over access to data and actions.

Using OAuth with Frontegg

Frontegg’s end-to-end and self-served authentication infrastructure is based on JSON Web Tokens. Our JWTs have been designed to adhere to the highest security standards. Therefore, our user management solution is also fully compliant with the OAuth protocol, along with OpenID Connect 1.0 (OIDC) as well. We cover all important bases that are required in the modern SaaS space. 

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