lestrrat-go/jwx is a Go module implementing various JWx (JWA/JWE/JWK/JWS/JWT, otherwise known as JOSE) technologies. A p2c parameter set too high in JWEs algorithm PBES2-* could lead to a denial of service. The JWE key management algorithms based on PBKDF2 require a JOSE Header Parameter called p2c (PBES2 Count). This parameter dictates the number of PBKDF2 iterations needed to derive a CEK wrapping key. Its primary purpose is to intentionally slow down the key derivation function, making password brute-force and dictionary attacks more resource- intensive. Therefore, if an attacker sets the p2c parameter in JWE to a very large number, it can cause a lot of computational consumption, resulting in a denial of service. This vulnerability has been addressed in commit 64f2a229b which has been included in release version 1.2.27 and 2.0.18. Users are advised to upgrade. There are no known workarounds for this vulnerability.
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Jwx | Lestrrat-go | * | 1.2.27 (excluding) |
| Jwx | Lestrrat-go | 2.0.0 (including) | 2.0.18 (excluding) |
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.