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Improper control of interaction frequency

Need​

Enforcement of rate limiting to control the frequency of user interactions

Context​

  • Usage of PHP 7.0 for server-side scripting and web development
  • Usage of Illuminate\Http\Request for handling HTTP requests in Laravel
  • Usage of Post for interacting with a PostgreSQL database

Description​

Non compliant code​

<?php

namespace App\\Http\\Controllers;

use Illuminate\\Http\\Request;

class PostController extends Controller
{
    public function store(Request $request)
    {
        $post = new Post;
        $post->title = $request->title;
        $post->body = $request->body;
        $post->save();

        return response()->json(['message' => 'Post created successfully'], 201);
    }
}

In the above code, we have a store method in the PostController which is responsible for storing new posts. This method takes a Request object as input, which includes user-submitted data. The title and body of the post are extracted from the request and saved to the database.

The vulnerability here is that there are no controls in place to limit the frequency of requests that a user can make to this endpoint. This means that a user could potentially flood the server with requests, leading to a Denial of Service (DoS) attack or exhausting the database resources.

Without any rate limiting, the server is left open to abuse. This could be in the form of spam, where a user or bot makes a large number of posts in a short amount of time. It could also be a form of brute force attack, where an attacker makes a large number of requests in an attempt to find a vulnerability or gain unauthorized access.

Steps​

  • Implement a rate limiting mechanism on the server side.
  • Use Laravel's built-in rate limiting features to limit the number of requests a user can make to the 'store' method within a certain time period.
  • Configure the rate limit to a reasonable number that prevents abuse but doesn't hinder normal usage.
  • Ensure that the rate limit applies per user or IP address to prevent a single user from overwhelming the server with requests.
  • Return a 429 (Too Many Requests) HTTP status code when a user exceeds their rate limit.

Compliant code​

<?php

namespace App\\Http\\Controllers;

use Illuminate\\Http\\Request;
use Illuminate\\Support\\Facades\\RateLimiter;

class PostController extends Controller
{
    public function __construct()
    {
        $this->middleware('throttle:60,1')->only('store');
    }

    public function store(Request $request)
    {
        if (RateLimiter::tooManyAttempts($request->ip(), 60)) {
            return response()->json(['message' => 'Too Many Requests'], 429);
        }

        $post = new Post;
        $post->title = $request->title;
        $post->body = $request->body;
        $post->save();

        RateLimiter::hit($request->ip(), 60);

        return response()->json(['message' => 'Post created successfully'], 201);
    }
}

The updated code now includes Laravel's built-in rate limiting features to limit the number of requests a user can make to the 'store' method within a certain time period.

In the constructor of the PostController, we added a middleware that applies a rate limit to the 'store' method. The 'throttle:60,1' argument means that a user can make up to 60 requests per minute.

In the 'store' method, we first check if the user has exceeded their rate limit using the RateLimiter::tooManyAttempts method. If they have, we return a 429 (Too Many Requests) HTTP status code.

After successfully creating a post, we increment the user's request count using the RateLimiter::hit method.

This way, we can prevent a single user from overwhelming the server with requests, thus fixing the vulnerability.

References​

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