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Insecure object reference - Session management

Need​

Secure session management

Context​

  • Requirement of PHP 7.0 or later for running the application
  • Usage of Request for making HTTP requests
  • Usage of the User dependency for managing user-related functionality
  • Usage of Auth for user authentication and authorization

Description​

Non compliant code​

public function logout(Request $request) {
    $email = $request->input('email');
    $user = User::where('email', $email)->first();
    if ($user) {
        Auth::logout($user);
        return response()->json(['message' => 'User logged out successfully.']);
    } else {
        return response()->json(['message' => 'User not found.']);
    }
}

The code snippet above is a function named logout which is used to log out users. It first gets the 'email' from the request input, then it uses this email to find the user in the database. If the user exists, it logs out the user and returns a success message. If the user doesn't exist, it returns an error message.

The vulnerability here is that the logout function doesn't check if the currently authenticated user is the same as the user that is being logged out. This means that if an attacker knows the email of another user, they can send a request to this endpoint with that email and log out the other user. This is an example of an Insecure Direct Object Reference (IDOR) vulnerability, where a user can directly reference an object that they should not have access to.

In this case, the object is the user session, and the attacker should not be able to manipulate other user's sessions. This can lead to situations where a user is unexpectedly logged out of their session, potentially leading to loss of unsaved work, confusion, and a poor user experience. In more severe cases, this could be part of a larger attack to take over the user's session.

Steps​

  • Remove the email parameter from the logout function. The function should not need any parameters to operate.
  • Instead of searching for a user based on the email, use the currently authenticated user. In Laravel, you can use Auth::user() to get the currently authenticated user.
  • Call the logout function on the currently authenticated user. This ensures that only the user who is currently logged in can log themselves out.
  • Ensure that your session management system invalidates the session on the server side when logout is called. This prevents the session from being hijacked after logout.

Compliant code​

public function logout() {
    $user = Auth::user();
    if ($user) {
        Auth::logout();
        return response()->json(['message' => 'User logged out successfully.']);
    } else {
        return response()->json(['message' => 'User not found.']);
    }
}

The updated code removes the email parameter from the logout function. This is a crucial step in fixing the insecure object reference vulnerability. The function should not need any parameters to operate, as it should only be able to log out the currently authenticated user.

Instead of searching for a user based on the email, the code now uses the currently authenticated user. In Laravel, you can use Auth::user() to get the currently authenticated user. This ensures that only the user who is currently logged in can log themselves out, preventing the possibility of closing active sessions of other users by knowing their e-mail.

The Auth::logout() function is called without any parameters. This function invalidates the user's session on the server side, which is a necessary step in secure session management. This prevents the session from being hijacked after logout.

If the user is not found or not authenticated, the function will return a 'User not found.' message. This is a good practice to inform the client that the operation was not successful without revealing any sensitive information.

References​

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