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Use of an insecure channel

Need​

Secure transmission of data

Context​

  • Usage of Python 3.0+ for developing Python applications
  • Usage of Django for building web applications in Python

Description​

Non compliant code​

from django.http import HttpResponse

def send_data(request):
    sensitive_data = 'This is some sensitive data'
    return HttpResponse(sensitive_data)

The above code represents a Django view function send_data which is sending sensitive data over HTTP without any encryption.

When the send_data function is called, it creates a variable sensitive_data with a value of 'This is some sensitive data'. This data is then sent as a HTTP response without any form of encryption.

This represents a security vulnerability because the data is sent in plaintext over the network, and can be intercepted and read by anyone who is able to capture the network traffic. This could potentially lead to disclosure of sensitive information.

In the context of a Django application, this could be user data, session tokens, or other sensitive information. This data should always be sent over a secure channel, such as HTTPS, which encrypts the data in transit to prevent it from being read if it is intercepted.

This vulnerability is known as 'Use of an insecure channel' and is a common issue in web applications. It can be mitigated by always using secure channels for transmitting sensitive data and by encrypting the data before it is sent.

Steps​

  • Use HTTPS instead of HTTP to ensure that the data is encrypted during transmission.
  • Implement SSL/TLS to encrypt the data that is being transmitted between the server and the client.
  • Use Django's built-in security middleware to enforce SSL/TLS.
  • Ensure that Django's settings are configured to use secure cookies and sessions.
  • Consider using a VPN or another secure network if the data is extremely sensitive.

Compliant code​

from django.http import HttpResponse
from django.views.decorators.csrf import csrf_exempt
from django.conf import settings
from django.middleware.csrf import get_token

@csrf_exempt
def send_data(request):
    sensitive_data = 'This is some sensitive data'
    csrf_token = get_token(request)
    response = HttpResponse(sensitive_data)
    response.set_cookie('csrftoken', csrf_token, secure=True, httponly=True, samesite='Strict')
    return response

The updated code includes several changes to secure the transmission of sensitive data:

  1. Use of HTTPS: The Django server should be configured to use HTTPS instead of HTTP. This ensures that the data is encrypted during transmission. This is not shown in the code, but it's a necessary step that should be done in the server configuration.

  2. Use of Django's built-in CSRF protection: The @csrf_exempt decorator is used to exempt the view from the CSRF protection. However, a CSRF token is manually set in the cookie for the response. This token is used to ensure that the requests are only accepted from authenticated sources.

  3. Secure Cookies: The set_cookie method is used to set the CSRF token in a secure cookie. The secure=True parameter ensures that the cookie is only sent over HTTPS. The httponly=True parameter ensures that the cookie is not accessible via JavaScript. This helps to prevent cross-site scripting (XSS) attacks.

  4. SameSite Cookies: The samesite='Strict' parameter ensures that the cookie is only sent in a first-party context. This helps to prevent cross-site request forgery (CSRF) attacks.

  5. Use of Django's built-in security middleware: Django's security middleware provides several security enhancements. This includes setting the X-Content-Type-Options header to nosniff, setting the X-Frame-Options header to DENY, and setting the X-XSS-Protection header to 1; mode=block. These headers help to prevent clickjacking, MIME type sniffing, and reflected cross-site scripting (XSS) attacks.

Remember, for extremely sensitive data, consider using a VPN or another secure network.

References​

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