How do you deal with OAuth token leakage or theft on your resource server?

1 What is token leakage or theft?

Token leakage or theft is when an unauthorized party obtains or intercepts an OAuth token, either from the user, the client application, or the network. An OAuth token is a string that represents the user's consent and scope of access to a resource server. If a malicious actor gets hold of a token, they can impersonate the user or the client and access the resource server without proper authorization. This can lead to data breaches, identity theft, or fraud.

2 How to prevent token leakage or theft?

The first step in protecting against token leakage or theft is to prevent it from occurring in the first place. You can do this by adhering to best practices for OAuth token management, such as using HTTPS for all OAuth requests and responses to encrypt the communication, utilizing short-lived and revocable tokens to limit the exposure and impact of a compromised token, employing refresh tokens and token rotation to renew access tokens regularly and invalidate old ones, using secure storage and transmission methods for tokens to avoid exposing them, and using PKCE (Proof Key for Code Exchange) for public clients to prevent code interception attacks and ensure that only the legitimate client can exchange the code for a token.

3 How to detect token leakage or theft?

Even if you adhere to the best practices, token leakage or theft can still occur. To mitigate this risk, you should monitor and audit your OAuth transactions and tokens. This can be done by logging and analyzing OAuth requests and responses to identify any unauthorized or invalid clients, users, scopes, or endpoints. Additionally, tracking and verifying token usage and expiration can help detect any excessive or expired tokens or tokens used from unexpected locations or devices. Lastly, implementing anomaly detection and alerting mechanisms can notify you of any abnormal or malicious patterns or behaviors.

4 How to respond to token leakage or theft?

If you detect or suspect that a token has been leaked or stolen, you must act swiftly and decisively to contain the damage and mitigate the risk. This can be done by revoking the compromised token and investigating the root cause and impact of the incident. Additionally, you should report and disclose the incident to the relevant parties, such as the user, the client, or the authorities. Finally, it is important to review and improve your OAuth security policies and practices to avoid similar incidents in the future.

5 How to test your OAuth security?

The last step in addressing OAuth token leakage or theft is to test your OAuth security, to ensure that best practices and countermeasures are implemented correctly and effectively. This can be done by carrying out regular security audits and assessments to evaluate your OAuth configuration and implementation, as well as conducting penetration testing and vulnerability scanning to simulate attacks and measure your OAuth resilience. Additionally, you can use security tools and frameworks to automate and simplify your OAuth security testing and validation. By following these steps, you can deal with OAuth token leakage or theft on your resource server, thereby protecting resources and users from unauthorized access and misuse.

6 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?