CWE-430: Deployment of Wrong Handler
Learn about CWE-430 (Deployment of Wrong Handler), its security impact, exploitation methods, and prevention guidelines.
What is Deployment of Wrong Handler?
• Overview: This vulnerability occurs when the wrong handler is assigned to process an object, leading to unintended behavior. For example, a servlet might be incorrectly used to expose the source code of a .JSP file, or the system might misidentify an object's type despite a specified type, causing security issues.
• Exploitation Methods:
- Attackers can exploit this vulnerability by manipulating inputs or requests to trigger the wrong handler, gaining unauthorized access or revealing sensitive information.
- Common attack patterns include forcing the system to execute inappropriate handlers or scripts and leveraging misconfigurations to bypass security controls.
• Security Impact:
- Direct consequences include unauthorized access to sensitive data, execution of malicious code, and exposure of internal system logic.
- Potential cascading effects involve data breaches, system downtime, and further exploitation of exposed vulnerabilities.
- Business impact can range from loss of customer trust and legal penalties to significant financial damage due to data breaches or service disruptions.
• Prevention Guidelines:
- Specific code-level fixes include validating handler assignments and ensuring handlers correspond correctly to object types and intended operations.
- Security best practices involve implementing strict access controls, regularly auditing handler assignments, and maintaining detailed logging for monitoring unexpected behavior.
- Recommended tools and frameworks include static code analysis tools to detect handler misassignments and frameworks that enforce strict type checking and handler associations.
Technical Details
Likelihood of Exploit: Not specified
Affected Languages: Not Language-Specific
Affected Technologies: Not specified
Vulnerable Code Example
```python web_server.py {10-17}
from flask import Flask, request
app = Flask(__name__)
def handle_admin_request():
return "Admin handler executed."
def handle_user_request():
return "User handler executed."
@app.route('/handle_request', methods=['POST'])
def handle_request():
user_role = request.form.get('role')
# Vulnerable code: wrong handler assignment based on user input
# An attacker can send 'admin' as the role to execute the admin handler
if user_role == 'admin':
handler = handle_admin_request
else:
handler = handle_user_request
return handler()
How to fix Deployment of Wrong Handler?
In this example, the vulnerability arises from directly assigning handlers based on user input without proper validation. An attacker can manipulate the 'role' parameter to access the admin handler, leading to unauthorized access.
To fix this, ensure that handler selection is based on secure, validated data. Instead of trusting user input directly, use a secure mechanism like a session or token to determine the user's role. This prevents malicious users from invoking handlers they shouldn't have access to.
Fixed Code Example
from flask import Flask, request, session
app = Flask(__name__)
app.secret_key = 'supersecretkey' # Required for session management
def handle_admin_request():
return "Admin handler executed."
def handle_user_request():
return "User handler executed."
@app.route('/handle_request', methods=['POST'])
def handle_request():
# Fixed code: secure role determination from session
user_role = session.get('role') # Role is securely stored in the session
# Prevents attackers from spoofing roles via request data
if user_role == 'admin':
handler = handle_admin_request
else:
handler = handle_user_request
return handler()
In this fixed example, the user's role is securely stored in the session, which is managed by the server and not influenced by the client. This prevents attackers from manipulating the role and ensures that the correct handler is deployed based on the authenticated user's true role.