Improper control of interaction frequency

Need

Enforce proper control of interaction frequency to prevent abuse and ensure fair resource allocation

Context

• Usage of Ruby 2.7.4 for Ruby programming and development

• Usage of Rails framework for building web applications

• Usage of ActiveRecord for Object-Relational Mapping (ORM) in database operations

Description

1. Non compliant code

class PostsController < ApplicationController
  def create
    post = Post.new(post_params)
    if post.save
      render json: post, status: :created
    else
      render json: post.errors, status: :unprocessable_entity
  end...

In the above code, we have a `PostsController` with a `create` action that is used to create new posts. The `create` action creates a new `Post` object with parameters `title` and `content` that are passed in the request. If the post is saved successfully, it returns the post as JSON with a status code of `201 (created)`. If it fails, it returns the errors as JSON with a status code of `422 (unprocessable entity)`. The vulnerability in this code is that there is no control over the frequency of interactions. This means that a user can send as many requests to this endpoint as they want in a short period of time. This can lead to a Denial of Service (DoS) attack where the server gets overwhelmed with too many requests and can't process legitimate requests. This can also lead to a user creating a large number of posts in a short period of time, which can be a form of spamming.

2. Steps

• Implement rate limiting to restrict the number of requests a user can make within a specific time frame.

• Use a middleware or a gem that provides rate limiting functionality.

• Configure the rate limit settings such as the maximum number of requests allowed per user and the time frame for the limit.

• Handle the rate limit exceeded scenario by returning an appropriate response, such as a 429 Too Many Requests status code.

• Consider implementing additional security measures like IP-based rate limiting or using a distributed rate limiting solution for scalability.

• Test the rate limiting functionality to ensure it is working as expected.

3. Secure code example

# Add the rack-attack gem to your Gemfile
gem 'rack-attack'

# Then run bundle install
bundle install

# Create a new file config/initializers/rack_attack.rb and add the following code:
class Rack::Attack...

The above code fixes the vulnerability by implementing rate limiting using the `rack-attack` gem. First, we add the `rack-attack` gem to the Gemfile and run `bundle install` to install it. Next, we create a new initializer file `rack_attack.rb` and configure the rate limit settings. In this case, we limit the number of requests to 5 per 5 seconds per IP address. Then, we update the `application.rb` file to use the `Rack::Attack` middleware. Finally, we update the `PostsController` to handle the rate limit exceeded scenario. If a user exceeds the rate limit, the server will respond with a 429 Too Many Requests status code and a JSON message indicating that the rate limit has been exceeded. This solution effectively prevents a user from making too many requests to the server in a short period of time, thus mitigating the risk of a denial-of-service attack.

References

• 108. Improper control of interaction frequency

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