Need

Enhancement of user privacy and data protection

Context

• Usage of Python 3 for scripting and software development
• Usage of Django for building web applications in Python

Description

Non compliant code

        from django.http import JsonResponse
from django.views import View
from .models import User

class UserInfoView(View):
    def get(self, request, *args, **kwargs):
        user_id = request.GET.get('user_id')
        user = User.objects.get(id=user_id)
        data = {
            'username': user.username,
            'email': user.email,
            'phone_number': user.phone_number,
        }
        return JsonResponse(data)
        
        

The above code is vulnerable to automatic information enumeration. In this Django view, the get method is used to fetch the user information based on the user_id passed in the request parameters.

The vulnerability lies in the fact that there is no authentication or authorization check before the user data is fetched and returned. This means that any user, authenticated or not, can pass any user_id and get the corresponding user's information.

This is a serious privacy concern as it allows for data enumeration. An attacker could potentially iterate over a range of user_ids and collect the personal information of all users in the system.

The information that is being exposed includes the username, email, and phone number
- all of which are considered sensitive personal information.

Steps

• Authenticate the user before providing any user information. This can be done by using Django's built-in authentication system.
• Use Django's permission and authorization system to ensure that the user requesting the information is the same user or has the necessary permissions to access the information.
• Instead of directly using the user_id from the GET request, use the user_id from the authenticated user's session.
• Implement rate limiting to prevent brute force attacks or data scraping.
• Encrypt sensitive data like email and phone number before sending it in the response.

Compliant code

        from django.http import JsonResponse
from django.views import View
from django.contrib.auth.decorators import login_required
from django.utils.decorators import method_decorator
from .models import User
from django.core.exceptions import PermissionDenied
from ratelimit.decorators import ratelimit

class UserInfoView(View):
    @method_decorator(login_required)
    @method_decorator(ratelimit(key='ip', rate='10/m'))  # Adjust rate limit as needed
    def get(self, request, *args, **kwargs):
        user_id = request.user.id
        user = User.objects.get(id=user_id)
        if request.user != user:
            raise PermissionDenied
        data = {
            'username': user.username,
            'email': user.email,  # Consider encrypting this
            'phone_number': user.phone_number,  # Consider encrypting this
        }
        return JsonResponse(data)
        
        

The updated code now includes several security measures to prevent automatic information enumeration:

1. User Authentication: The @login_required decorator ensures that the user is authenticated before they can access the get method of the UserInfoView. This means that only logged-in users can access this view.

2. User Authorization: The code checks if the request.user is the same as the user whose information is being requested. If they are not the same, a PermissionDenied exception is raised. This ensures that users can only access their own information.

3. Rate Limiting: The @ratelimit decorator is used to limit the number of requests that can be made to this view from a single IP address. This helps to prevent brute force attacks and data scraping.

4. Data Encryption: The code includes comments suggesting that sensitive data (like email and phone number) should be encrypted before being sent in the response. This is an additional measure that can be taken to protect user data.

Remember to adjust the rate limit as needed for your specific application, and to implement data encryption for sensitive data if it is not already in place.

References

• 283. Automatic information enumeration - Personal Information