Prevent IDOR Vulnerabilities in Symfony Apps

Insecure Direct Object References (IDOR) are among the most common and dangerous web vulnerabilities that occur when an application exposes internal object references to users. Symfony, being a widely-used PHP framework, is no exception if proper access controls are not implemented.

In this blog post, we’ll explore how IDOR vulnerabilities can impact Symfony applications, walk through real-world code examples, and show you how to mitigate these threats effectively. We’ll also introduce a free website vulnerability scanner online that scans for vulnerabilities, including IDOR, and provides a full vulnerability report.

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🔍 What is Insecure Direct Object Reference (IDOR)?

IDOR occurs when a web application exposes a reference to an internal object, such as a file, database record, or account, without proper authorization checks. Attackers can manipulate these references to gain unauthorized access to data.

Example:

GET /user/profile/123

If user 123 is not the currently authenticated user, and no access control checks are in place, an attacker could change the ID to another user's ID, like /user/profile/124, and access their private data.

🚨 Real-World Symfony IDOR Vulnerability Example

Let’s look at a real-world insecure code snippet in Symfony that could lead to IDOR.

❌ Vulnerable Symfony Code

// src/Controller/UserController.php

use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;

use Symfony\Component\HttpFoundation\Request;

use Symfony\Component\Routing\Annotation\Route;

class UserController extends AbstractController

{

    /**

     * @Route("/user/profile/{id}", name="user_profile")

     */

    public function profile($id)

    {

        $user = $this->getDoctrine()

                     ->getRepository(User::class)

                     ->find($id);

        return $this->render('user/profile.html.twig', [

            'user' => $user

        ]);

    }

}

🔍 Problem:

This code fetches the user by ID directly from the URL without checking if the current logged-in user has the right to view that profile. An attacker can change the {id} and view someone else’s data.

✅ Secure Symfony Code to Prevent IDOR

Use Symfony's built-in security features to ensure proper authorization.

use Symfony\Component\Security\Core\Exception\AccessDeniedException;

/**

 * @Route("/user/profile/{id}", name="user_profile")

 */

public function profile($id)

{

    $currentUser = $this->getUser();

    $user = $this->getDoctrine()

                 ->getRepository(User::class)

                 ->find($id);

    if ($user !== $currentUser) {

        throw new AccessDeniedException('You are not authorized to access this profile.');

    }

    return $this->render('user/profile.html.twig', [

        'user' => $user

    ]);

}

✅ Better Practice: Fetch data directly from the session user

/**

 * @Route("/user/profile", name="user_profile")

 */

public function profile()

{

    $user = $this->getUser();

    return $this->render('user/profile.html.twig', [

        'user' => $user

    ]);

}

This approach ensures no user ID is exposed in the URL and avoids IDOR completely.

🛠 Free Tool to Detect IDOR Vulnerabilities

We offer a website vulnerability scanner that automatically scans for vulnerabilities including IDOR, XSS, CSRF, and more.

📸 Screenshot of the tool's landing page

Screenshot of the free tools webpage where you can access security assessment tools.