Improper Verification of Cryptographic Signature (CWE-347)

Improper Verification of Cryptographic Signature

The product does not verify, or incorrectly verifies, the cryptographic signature for data.

Cryptographic signatures are used to verify the authenticity and integrity of data. When signature verification is missing or incorrectly implemented, attackers can forge or tamper with data.

Prévalence

Élevée

Fréquemment exploitée

Impact

Critique

1 règles de sévérité critique

Prévention

Documentée

4 exemples de correctifs

2 Prévention

Comment corriger cette vulnérabilité

Stratégies de prévention pour Improper Signature Verification basées sur 4 règles de détection Shoulder.

🐍 Python Tout voir Python détails →

FastAPI JWT Security Issues HIGH

Load JWT secret from environment and explicitly specify allowed algorithms

+11 -6 python

- from jose import jwt
- 
- SECRET = "my-secret-key"
- 
- def decode_token(token: str):
-     return jwt.decode(token, SECRET)
+ from pydantic_settings import BaseSettings
+ from jose import jwt
+ 
+ class Settings(BaseSettings):
+     SECRET_KEY: str
+     ALGORITHM: str = "HS256"
+ 
+ settings = Settings()
+ 
+ def decode_token(token: str):
+     return jwt.decode(token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM])

JWT Algorithm Confusion Attack CRITICAL

Always specify allowed algorithms explicitly when decoding JWT tokens

+13 -7 python

  import jwt
- from flask import request
- 
- @app.route('/api/user')
- def get_user():
-     token = request.headers.get('Authorization')
-     payload = jwt.decode(token, SECRET_KEY, verify=False)
-     return {'user': payload['user_id']}
+ import os
+ from flask import request
+ 
+ SECRET_KEY = os.environ['JWT_SECRET']
+ 
+ @app.route('/api/user')
+ def get_user():
+     token = request.headers.get('Authorization')
+     try:
+         payload = jwt.decode(token, SECRET_KEY, algorithms=['HS256'])
+         return {'user': payload['user_id']}
+     except jwt.InvalidTokenError:
+         return {'error': 'Invalid token'}, 401

🐹 Go Tout voir Go détails →

JWT Security Vulnerabilities HIGH

Validate JWT algorithm explicitly, use strong secrets, and set expiration

+4 -1 go

  func parseToken(tokenString string) (*jwt.Token, error) {
      return jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
-         return []byte("secret"), nil
+         if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
+             return nil, fmt.Errorf("unexpected method: %v", token.Header["alg"])
+         }
+         return []byte(os.Getenv("JWT_SECRET")), nil
      })
  }

🟨 JavaScript Tout voir JavaScript détails →

JWT Decode Without Verification HIGH

Use jwt.verify() instead of jwt.decode() to validate token signatures

+3 -1 javascript

- const decoded = jwt.decode(token);
+ const decoded = jwt.verify(token, process.env.JWT_SECRET, {
+   algorithms: ['RS256']
+ });
  req.user = decoded;

Pratiques clés

Use of jwt

3 Détection

Trouvez les vulnérabilités dans votre code

Utilisez Shoulder pour scanner votre code à la recherche de patterns Improper Verification of Cryptographic Signature. 4 règles.

terminal

# Scan with Shoulder CLI
npx @shoulderdev/cli trust --cwe=347

# Or scan entire project
npx @shoulderdev/cli trust .

Règles de Détection (4)

🐍 Python 2 rules

FastAPI JWT Security Issues HIGH

Detects JWT security issues in FastAPI applications including: - Weak or hardcoded secrets - Missing algorithm verification - Insufficient token validation - Insecure token storage patterns

JWT Algorithm Confusion Attack CRITICAL

Detects JWT tokens decoded without algorithm verification or accepting the 'none' algorithm, allowing token forgery.

🐹 Go 1 rules

JWT Security Vulnerabilities HIGH

JWT allows "none" algorithm, uses weak secret, or lacks expiration.

🟨 Javascript 1 rules

JWT Decode Without Verification HIGH

Detects use of jwt.decode() without proper verification, leading to authentication bypass. jwt.decode() decodes a JWT token WITHOUT verifying its signature. This means an attacker can create a token with any payload they want, and the application will trust it. Common mistakes: - Using jwt.decode() instead of jwt.verify() - Decoding token for inspection then trusting the payload - Using decoded payload for authorization decisions The decoded payload should NEVER be trusted for security decisi

🔷 Typescript 1 rules

JWT Decode Without Verification HIGH

4 Signes d'Alerte

Ce qu'il faut surveiller lors des revues de code

Ces patterns indiquent des vulnérabilités potentielles Improper Verification of Cryptographic Signature. Recherchez-les lors des revues de code et des audits de sécurité.

🟠

JWT implementation has security vulnerabilities fastapi-jwt-security

🟠

JWT security issues in FastAPI applications including: - Weak or hardcoded secrets - Missing algorit fastapi-jwt-security

🟠

use of jwt javascript-jwt-decode-without-verify

🔴

JWT tokens decoded without algorithm verification or accepting the 'none' algorithm, allowing token python-jwt-algorithm-confusion

🔍

Scannez votre base de code pour Improper Verification of Cryptographic Signature

Shoulder CLI trouve les motifs vulnérables dans toute votre base de code.

npx shoulder trust Parcourir toutes les règles