What is JWT?

JWT, or JSON Web Token, is a compact and self-contained method for securely transmitting information between parties as a JSON object. It consists of three parts: a header, payload, and signature, encoded using Base64. JWTs are commonly used for authentication and authorization in web applications and APIs, offering stateless and scalable solutions. They are widely adopted due to their flexibility and security, but require careful consideration for proper validation and protection against security threats.

Exploits

One vulnerability with JWTs is weak signature algorithms. Attackers can exploit this by cracking JWT signatures using tools like Hashcat.

Using Hashcat:

1. Extract the JWT signature.
2. Use Hashcat to crack the signature hash using a wordlist or custom rules.
3. Adjust parameters based on the JWT algorithm (e.g., HMAC-SHA256 or HMAC-SHA512).

To mitigate this risk, use strong cryptographic algorithms for signing JWTs, secure key management practices, and implement additional security measures like token expiration and revocation.