Ratpack versions before 1.6.1 generate a session ID using a cryptographically weak PRNG in the JDKs ThreadLocalRandom. This means that if an attacker can determine a small window for the server start time and obtain a session ID value, they can theoretically determine the sequence of session IDs.
The product uses a Pseudo-Random Number Generator (PRNG) in a security context, but the PRNG’s algorithm is not cryptographically strong.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Ratpack | Ratpack_project | * | 1.6.1 (excluding) |
When a non-cryptographic PRNG is used in a cryptographic context, it can expose the cryptography to certain types of attacks. Often a pseudo-random number generator (PRNG) is not designed for cryptography. Sometimes a mediocre source of randomness is sufficient or preferable for algorithms that use random numbers. Weak generators generally take less processing power and/or do not use the precious, finite, entropy sources on a system. While such PRNGs might have very useful features, these same features could be used to break the cryptography.