Need

Secure access control and protection of personal information

Context

• Usage of Python 3 for scripting and application 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 UpdateUserView(View):
    def post(self, request, *args, **kwargs):
        user_id = request.POST.get('user_id')
        new_email = request.POST.get('new_email')
        user = User.objects.get(id=user_id)
        user.email = new_email
        user.save()
        return JsonResponse({'status': 'success'})
        
        

The code above represents a View in Django that allows updating a user's email. This view is vulnerable to Insecure Direct Object References (IDOR) as it does not verify if the user making the request is the same user whose email is being updated.

In the UpdateUserView class, the post method retrieves the user_id and new_email from the POST request. It then uses the user_id to fetch the user object from the database and updates the email attribute of the user object with the new_email from the POST request.

The vulnerability lies in the fact that there is no authentication or authorization check being performed. Any user can provide any user_id and new_email value in the POST request and change the email of any user in the system. This can lead to unauthorized access and modification of user data, violating the principle of confidentiality and integrity of user data.

Steps

• First, you need to implement an authentication check to ensure that the user making the request is authenticated.
• Second, you should verify that the authenticated user has the necessary permissions to update the user information. This can be done by comparing the user_id from the request with the id of the authenticated user.
• Third, consider using Django's built-in forms or serializers to handle data validation and avoid direct manipulation of model objects.
• Lastly, always return a meaningful response to the user. If the user does not have the necessary permissions or if the operation fails, the response should indicate this.

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

class UpdateUserView(View):
    @method_decorator(login_required)
    def post(self, request, *args, **kwargs):
        user_id = request.POST.get('user_id')
        new_email = request.POST.get('new_email')
        
        # Check if the user_id from the request matches the id of the authenticated user
        if request.user.id != user_id:
            return JsonResponse({'status': 'error', 'message': 'You do not have permission to update this user.'})
        
        try:
            user = User.objects.get(id=user_id)
            user.email = new_email
            user.save()
            return JsonResponse({'status': 'success'})
        except User.DoesNotExist:
            return JsonResponse({'status': 'error', 'message': 'User does not exist.'})
        
        

The updated code now includes an authentication check using Django's built-in login_required decorator. This ensures that the user making the request is authenticated.

Next, we added a permission check to verify that the authenticated user has the necessary permissions to update the user information. This is done by comparing the user_id from the request with the id of the authenticated user. If they do not match, the request is denied and an error message is returned.

We also added a try/except block to handle the case where the user does not exist. If the User.objects.get(id=user_id) call fails, it will raise a User.DoesNotExist exception. We catch this exception and return an error message to the user.

Finally, we always return a meaningful response to the user. If the user does not have the necessary permissions or if the operation fails, the response will indicate this.

References

• 286. Insecure object reference - Personal information