Fix Logic Flow Bypass in FuelPHP
Logic Flow Bypasses in FuelPHP often manifest when developers trust client-side state or fail to enforce strict state machine transitions in multi-step controllers. Attackers exploit these by jumping directly to 'success' endpoints or manipulating hidden inputs to skip authorization gates. As a researcher, you don't look for syntax errors; you look for broken business logic that assumes the user followed the intended path.
The Vulnerable Pattern
public function action_process_order() { // VULNERABILITY: Trusting a POST parameter to verify payment status $is_paid = Input::post('payment_confirmed', false); $order_id = Input::post('order_id');if ($is_paid) { $order = Model_Order::find($order_id); $order->status = 'shipped'; $order->save(); return Response::forge(View::forge('order/success')); } return Response::forge(View::forge('order/failed'));
}
The Secure Implementation
The vulnerable snippet suffers from 'Parameter Pollution/Injection' where the business logic relies on the user's input (`payment_confirmed`) to determine the flow. An attacker can simply intercept the request and set this to true. The secure implementation enforces a server-side state machine. It uses FuelPHP's Session class to track the process and verifies the order status against the database. Crucially, it deletes the session state after completion to prevent 'State Replay' attacks, ensuring the logic flow cannot be bypassed or re-entered out of sequence.
public function action_process_order() { // MITIGATION: Verify state via Server-Side Session and Database integrity $order_id = Session::get('pending_order_id'); $payment_token = Session::get('payment_verified_token');if (!$order_id || !$payment_token) { Log::error('Unauthorized access attempt to process_order'); Response::redirect('checkout/step1'); } $order = Model_Order::find($order_id); // Verify the payment actually happened via API or DB check, not user input if ($order && $order->payment_status === 'verified') { $order->status = 'shipped'; $order->save(); // Invalidate state to prevent replay attacks Session::delete('pending_order_id'); Session::delete('payment_verified_token'); return Response::forge(View::forge('order/success')); } throw new HttpNotFoundException;
}
Your FuelPHP API
might be exposed to Logic Flow Bypass
74% of FuelPHP apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
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