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User Enumeration - Wordpress

Need​

Prevention of user enumeration in WordPress

Context​

  • Requirement of PHP 7.0 or higher for running the application
  • Usage of Laravel framework for PHP web development

Description​

Non compliant code​

// Vulnerable Code
public function getUsers(Request $request) {
    $users = User::all();
    return response()->json($users);
}

The above PHP function is a simple endpoint in a Laravel application that returns a list of all users in the system. It uses the Laravel's Eloquent ORM to fetch all users from the database and then returns them as a JSON response.

The vulnerability here is that there is no access control or permission checking in place to ensure that only authorized users can access this endpoint. This means that any user, even those not logged in, can access this endpoint and get a list of all users. This is a User Enumeration vulnerability because it allows potential attackers to enumerate valid users in the application.

In the context of a WordPress application, this could potentially expose sensitive user information such as usernames, email addresses, and user roles. This information can be used by an attacker to perform further attacks such as brute force attacks, phishing, or social engineering.

The endpoint does not check if the user making the request has the necessary permissions to access this information. This is a violation of the principle of least privilege, which states that a user should only be able to access the information and resources that are necessary for their legitimate purpose.

In a real-world application, this could lead to serious privacy breaches and potential legal issues, as well as damage to the reputation of the application or organization. Therefore, it is crucial to implement proper access control mechanisms to prevent unauthorized access to sensitive information.

Steps​

  • Implement an authentication mechanism to ensure only authorized users can access the user list.
  • Add role-based access control (RBAC) to limit the visibility of user data based on the role of the authenticated user.
  • Avoid returning all user data. Instead, return only the necessary data.
  • Implement rate limiting to prevent automated attacks.
  • Log and monitor unusual activities for early detection of potential attacks.

Compliant code​

public function getUsers(Request $request) {
    // Check if user is authenticated
    if (Auth::check()) {
        // Check if user has the right role
        if (Auth::user()->hasRole('admin')) {
            // Get only necessary user data
            $users = User::all('id', 'name', 'email');
            return response()->json($users);
        } else {
            return response()->json(['error' => 'Unauthorized'], 403);
        }
    } else {
        return response()->json(['error' => 'Unauthenticated'], 401);
    }
}

The updated code first checks if a user is authenticated using Laravel's built-in Auth::check() function. If the user is not authenticated, it returns a 401 error with a message 'Unauthenticated'.

If the user is authenticated, the code then checks if the user has the 'admin' role. This is done using a hypothetical hasRole method on the User model, which you would need to implement. This method should return true if the user has the specified role, and false otherwise. If the user does not have the 'admin' role, the code returns a 403 error with a message 'Unauthorized'.

If the user is authenticated and has the 'admin' role, the code retrieves a list of all users. However, instead of retrieving all user data, it only retrieves the 'id', 'name', and 'email' fields. This is done using the all method on the User model with the desired fields as arguments.

This code does not implement rate limiting or logging and monitoring of unusual activities. These features should be implemented at a higher level in your application, typically in middleware.

References​

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