What are the most effective ways to secure your OAuth implementation?

2 Validate Redirect URIs

The second rule for securing your OAuth implementation is to validate the redirect URIs that are used to send the user back to the client after obtaining the authorization code or the access token. The redirect URIs should be registered and verified by the authorization server and match exactly the ones provided by the client in the authorization request. This prevents attackers from using open redirectors or malicious URIs to hijack the OAuth flow and obtain unauthorized access to the user's resources or account.

3 Use PKCE

The third rule for securing your OAuth implementation is to use PKCE (Proof Key for Code Exchange) if you are using the authorization code grant type with a public client, such as a mobile app or a browser-based app. PKCE is an extension of OAuth that adds an extra layer of security by requiring the client to generate and send a random code verifier along with the authorization request, and then use it to derive and send a code challenge along with the authorization code to exchange it for an access token. This ensures that only the client that initiated the authorization request can obtain the access token and prevents attackers from exploiting code interception or code injection attacks.

4 Use Refresh Tokens

The fourth rule for securing your OAuth implementation is to use refresh tokens if you need to maintain long-term access to the user's resources without requiring them to re-authenticate frequently. Refresh tokens are long-lived tokens that can be used to obtain new access tokens when they expire or become invalid. However, refresh tokens should be stored securely by the client and treated as sensitive information, as they can grant access to the user's resources until they are revoked. You should also implement mechanisms to limit the scope, lifetime, and usage of refresh tokens and revoke them when they are compromised or no longer needed.

5 Use Token Binding

The fifth rule for securing your OAuth implementation is to use token binding if you want to enhance the security and integrity of your tokens. Token binding is a technique that binds the tokens to the TLS connection between the client and the server, making them unusable if they are stolen or leaked. Token binding requires both the client and the server to support the token binding protocol and to generate and exchange cryptographic keys that are used to bind the tokens. Token binding can prevent token replay attacks and protect against token theft or leakage.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?