Fix Business Logic Errors in FuelPHP
Business logic vulnerabilities in FuelPHP are not syntax errors but design flaws that bypass intended application workflows. These occur when developers trust client-side data for critical operations like price calculations, state transitions, or privilege escalations. In FuelPHP, the lack of strict server-side state machine validation in controllers often allows attackers to manipulate Model properties directly via Input parameters.
The Vulnerable Pattern
public function post_update_order($id)
{
$order = Model_Order::find($id);
// VULNERABILITY: Blindly trusting the 'status' and 'total_price' from POST data
// An attacker can change the status to 'paid' or set the price to 0.01
$order->status = Input::post('status');
$order->total_price = Input::post('total_price');
$order->save();
return Response::forge(json_encode(['status' => 'success']));
}The Secure Implementation
The vulnerable code allows for Parameter Tampering and IDOR. It assumes the user is the owner and that the input 'status' is valid. The secure implementation enforces three layers of defense: 1. Ownership Verification: Ensuring the order belongs to the authenticated user. 2. State Machine Logic: Hardcoding allowed status transitions so a user cannot jump from 'pending' to 'shipped' or 'paid'. 3. Integrity: Removing the ability to update sensitive fields like 'total_price' via client-side input, ensuring the server remains the single source of truth for business data.
public function post_update_order($id) { $user_id = Auth::get_user_id(); $order = Model_Order::find_by(['id' => $id, 'user_id' => $user_id]);if (!$order) { throw new HttpNotFoundException; } $requested_status = Input::post('status'); $allowed_transitions = [ 'pending' => ['cancelled', 'processing'], 'processing' => ['shipped'] ]; // SECURE: Validate state machine transition if (!isset($allowed_transitions[$order->status]) || !in_array($requested_status, $allowed_transitions[$order->status])) { return Response::forge('Invalid status transition', 400); } // SECURE: Price is NEVER updated from user input; it is recalculated server-side $order->status = $requested_status; $order->save(); return Response::forge(json_encode(['status' => 'updated']));
}
Your FuelPHP API
might be exposed to Business Logic Errors
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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