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Improper control of interaction frequency

Need​

Enforce rate limiting to control the frequency of user interactions

Context​

  • Usage of Python 3 for writing and executing Python code
  • Usage of Django for building web applications in Python

Description​

Non compliant code​

from django.http import HttpResponse
from django.views import View

class MyView(View):
    def post(self, request, *args, **kwargs):
        # Process the request
        return HttpResponse('Hello, World!')

In the above code snippet, we have a simple Django view that processes POST requests. The post method is a built-in method in Django that handles POST requests to the server.

Here, any client can send unlimited POST requests to this view without any restriction. This can lead to several issues such as Denial of Service (DoS) attacks where an attacker could potentially send a large number of requests to the server, causing it to become overwhelmed and unresponsive to other users.

Another issue could be resource exhaustion. Each request takes up server resources to process. Without a limit, an attacker could send enough requests to use up all available server resources, causing legitimate requests to fail or be slow.

This is a clear example of the vulnerability "Improper control of interaction frequency". The system does not limit the amount of requests (rate limit) that a user can post to the server in a short period of time.

Steps​

  • Implement a rate limiting mechanism to control the frequency of requests from a single user.
  • Use Django's middleware to create a custom rate limiter.
  • In the custom middleware, track the number of requests made by each user within a certain time frame.
  • If a user exceeds the maximum number of requests allowed within that time frame, return an error response.
  • Consider using a third-party library like Django Ratelimit for easier implementation.

Compliant code​

from django.http import HttpResponse
from django.views import View
from django_ratelimit.decorators import ratelimit

class MyView(View):
    @ratelimit(key='ip', rate='10/m', block=True)
    def post(self, request, *args, **kwargs):
        # Process the request
        return HttpResponse('Hello, World!')

The above code uses the Django Ratelimit library to implement rate limiting on the post method of MyView. The @ratelimit decorator is used to specify the rate limiting rules.

The key argument is set to 'ip', which means the rate limiting will be based on the IP address of the incoming request. This means that each unique IP address will be treated as a unique user.

The rate argument is set to '10/m', which means that a maximum of 10 requests are allowed per minute from each unique IP address.

The block argument is set to True, which means that if a user exceeds the rate limit, their request will be blocked and they will receive a 429 'Too Many Requests' response.

This way, the system controls the frequency of requests from a single user, mitigating the vulnerability of improper control of interaction frequency.

References​

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