Skip to main content

Insufficient data authenticity validation

Need​

Enhanced data authenticity validation and verification

Context​

  • Usage of Python 3 for building and running Python applications
  • 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 UserProfile

class UpdateProfileView(View):
    def post(self, request, *args, **kwargs):
        user_id = request.POST.get('user_id')
        name = request.POST.get('name')

        # updating user profile without checking the authenticity of the data
        UserProfile.objects.filter(id=user_id).update(name=name)

        return JsonResponse({'status': 'success'})

In the above code, we have a Django view named UpdateProfileView. This view is responsible for updating the UserProfile model. The post method in this view is accepting two POST parameters, user_id and name.

The problem in this code is that it directly takes the user_id and name from the POST request and updates the UserProfile object without any validation. This means anyone can send a POST request with any user_id and name and the system will blindly update the data in the database.

This is a serious vulnerability because it allows an attacker to update any user's profile with invalid data. For example, an attacker can use a non-existing name to update a user's profile. This can lead to data corruption and can have serious consequences.

The application is not checking if the user has the permission to modify the fields. It is also not validating if the name exists or not. This is a classic example of insufficient data authenticity validation.

Steps​

  • Authenticate the user making the request to ensure they have the necessary permissions to update the profile.
  • Validate the input data to ensure it is in the correct format and does not contain any malicious content. For example, the 'name' field should not contain any special characters or SQL injection attempts.
  • Check if the user profile exists before attempting to update it. If the user profile does not exist, return an appropriate error message.
  • Implement error handling to manage any issues that may arise during the update process, such as database errors.

Compliant code​

from django.http import JsonResponse
from django.views import View
from django.core.exceptions import ObjectDoesNotExist
from .models import UserProfile

class UpdateProfileView(View):
    def post(self, request, *args, **kwargs):
        user_id = request.POST.get('user_id')
        name = request.POST.get('name')

        # Authenticate the user
        if request.user.is_authenticated and request.user.id == user_id:
            # Validate the input data
            if name.isalpha():
                try:
                    # Check if the user profile exists
                    user_profile = UserProfile.objects.get(id=user_id)
                    # Update the user profile
                    user_profile.name = name
                    user_profile.save()
                    return JsonResponse({'status': 'success'})
                except ObjectDoesNotExist:
                    return JsonResponse({'status': 'error', 'message': 'User profile does not exist'})
            else:
                return JsonResponse({'status': 'error', 'message': 'Invalid input data'})
        else:
            return JsonResponse({'status': 'error', 'message': 'User not authenticated or does not have permission'})

The updated code now includes several checks to fix the vulnerability:

  1. User Authentication: The code checks if the user making the request is authenticated and if they are the owner of the profile they are trying to update. This ensures that only the rightful owner can update their profile.

  2. Input Validation: The code checks if the 'name' field contains only alphabetic characters. This is a basic form of input validation to prevent special characters or SQL injection attempts.

  3. Existence Check: The code checks if the user profile exists before attempting to update it. If the user profile does not exist, it returns an error message.

  4. Error Handling: The code uses a try-except block to handle any errors that may occur when trying to retrieve the user profile from the database. If an error occurs, it returns an appropriate error message.

References​

Last updated on