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Unauthorized access to screen

Need​

Prevention of unauthorized access to client information

Context​

  • Usage of Python 3 for writing and executing Python code
  • Usage of Django for web application development

Description​

Non compliant code​

from django.contrib.auth.decorators import login_required
from django.shortcuts import render

@login_required
def user_window(request):
    user = request.user
    client_data = ClientData.objects.get(user=user)
    return render(request, 'user_window.html', {'client_data': client_data})

In the code snippet above, we have a Django view function user_window that retrieves client data associated with the currently logged in user and passes it to a template. The function is protected by the @login_required decorator, which means only authenticated users can access this view.

The vulnerability here is that any authenticated user (in this case, an advisor) can access this view and, by extension, the client data. This is because the @login_required decorator only checks if a user is authenticated, not if they have the appropriate permissions to access the data.

Additionally, the view function retrieves the client data without checking if the currently logged in user is actually the owner of the data. This means that an advisor could potentially access the data of other clients simply by manipulating the request. This could lead to unauthorized access and potential data breaches.

Steps​

  • Implement role-based access control (RBAC) to restrict the data that different types of users can access.
  • Ensure that only the client themselves can access their own data. This can be done by checking if the logged-in user is the same as the user whose data is being accessed.
  • Encrypt sensitive data to add an extra layer of security. Even if an unauthorized user gains access, they won't be able to understand the data without the decryption key.
  • Log and monitor all access to sensitive data. This will help in identifying any unauthorized access attempts.
  • Regularly update and patch the system to fix any security vulnerabilities that could be exploited.

Compliant code​

from django.contrib.auth.decorators import login_required
from django.shortcuts import render
from django.http import HttpResponseForbidden

@login_required
def user_window(request):
    user = request.user
    client_data = ClientData.objects.get(user=user)
    
    # Check if the logged-in user is the same as the user whose data is being accessed
    if request.user != client_data.user:
        return HttpResponseForbidden()
    
    return render(request, 'user_window.html', {'client_data': client_data})

The updated code includes a check to ensure that the logged-in user is the same as the user whose data is being accessed. This is done using an if statement that compares request.user (the logged-in user) with client_data.user (the user whose data is being accessed). If these two are not the same, the function returns an HttpResponseForbidden, which is a HTTP response with status code 403 indicating that the server understood the request, but it refuses to authorize it. This effectively prevents an advisor from accessing a client's data.

Please note that this is just one part of the solution. To fully secure the application, you should also implement role-based access control (RBAC), encrypt sensitive data, log and monitor all access to sensitive data, and regularly update and patch the system.

References​

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