Skip to main content

Spoofing

Need​

Prevention of unauthorized access and impersonation

Context​

  • Usage of PHP for server-side scripting and web development
  • Usage of Request for making HTTP requests
  • Usage of the User dependency for user-related functionality

Description​

Non compliant code​

public function spoofingAction(Request $request)
{
    $user_id = $request->input('user_id');
    $message = $request->input('message');
    
    $user = User::find($user_id);
    
    $user->messages()->create([
        'content' => $message,
        'sent_by' => 'System',
    ]);
}

In the above code, we have a method spoofingAction in a Laravel controller. This method takes a Request object as a parameter which contains the data sent by the client.

The method retrieves the user_id and message from the request. It then finds the user with the provided user_id in the database.

After finding the user, it creates a new message associated with the user and sets the sent_by field to 'System'.

The vulnerability here is that there is no check to see if the request is actually coming from the system or another user with the correct permissions. This means that an attacker could potentially send a request with any user_id and message they want, and the application would accept it and create a message that appears to have been sent by the system.

This could be used to send misleading or harmful messages to users, or to perform actions on behalf of users with more privileges.

The spoofing vulnerability here is that the code trusts the user_id and message provided in the request without any validation or authentication.

Steps​

  • Validate the user_id input to ensure it belongs to the currently authenticated user.
  • Do not allow the 'sent_by' field to be hardcoded as 'System'. Instead, it should be set to the authenticated user's ID or username.
  • Implement proper access controls to ensure that only authorized users can send messages or perform actions on behalf of other users.
  • Log all actions performed in the system, including who performed the action and when it was performed, to allow for auditing and detection of any spoofing attempts.
  • Consider using a CSRF token to prevent cross-site request forgery, which could be used to perform actions on behalf of a user without their knowledge.

Compliant code​

public function spoofingAction(Request $request)
{
    $user_id = $request->input('user_id');
    $message = $request->input('message');
    
    // Validate the user_id input to ensure it belongs to the currently authenticated user.
    if(Auth::user()->id != $user_id) {
        return response()->json(['error' => 'Unauthorized'], 401);
    }
    
    $user = User::find($user_id);
    
    // Do not allow the 'sent_by' field to be hardcoded as 'System'. Instead, it should be set to the authenticated user's ID or username.
    $user->messages()->create([
        'content' => $message,
        'sent_by' => Auth::user()->username,
    ]);
    
    // Log all actions performed in the system, including who performed the action and when it was performed.
    Log::info('Message sent by '.Auth::user()->username.' at '.now());
}

The updated code now includes several security measures to prevent spoofing attacks.

Firstly, it checks if the user_id input matches the ID of the currently authenticated user. If not, it returns an 'Unauthorized' error. This ensures that users can only perform actions on their own behalf, not on behalf of other users.

Secondly, it no longer hardcodes the 'sent_by' field as 'System'. Instead, it sets this field to the username of the authenticated user. This ensures that the true sender of the message is always accurately recorded.

Finally, it logs all actions performed in the system, including who performed the action and when it was performed. This allows for auditing and detection of any spoofing attempts.

In addition to these measures, it is also recommended to use a CSRF token to prevent cross-site request forgery, which could be used to perform actions on behalf of a user without their knowledge. This can be implemented using Laravel's built-in CSRF protection.

References​

Last updated on