Refresh JSON Web Tokens (JWTs) are a crucial part of maintaining user authentication sessions without requiring frequent logins. However, if not implemented securely, refresh tokens can become a major security risk. Here are some common ways refresh JWTs can be compromised:

1. Token Theft via Storage Vulnerabilities

Storing refresh tokens improperly is one of the biggest risks. If stored in localStorage or sessionStorage, they are vulnerable to Cross-Site Scripting (XSS) attacks, where an attacker injects malicious scripts into a web page to steal tokens. A more secure approach is to store refresh tokens in HTTP-only cookies, which are inaccessible to JavaScript.

2. Token Interception via Man-in-the-Middle (MitM) Attacks

If refresh tokens are transmitted over an insecure connection (e.g., without HTTPS), they can be intercepted by an attacker. Always use TLS/SSL encryption to protect token transmission.

3. Token Reuse and Replay Attacks

If an attacker gains access to a refresh token, they can repeatedly use it to generate new access tokens. Token rotation, where a new refresh token is issued with each refresh request, helps mitigate this risk. If an old refresh token is reused, the system should detect and revoke it.

4. Compromised Devices

If an attacker gains control of a user’s device, they can extract stored refresh tokens. Implementing device-based authentication and token expiration policies helps minimize risk.

To enhance security, developers should follow best practices such as short refresh token lifespans, revocation mechanisms, and anomalous activity detection to prevent unauthorized access.

MIC Solutions Ltd would be delighted to consult with your organisation to deliver a robust and secure Identity Management system.