How the CVE Works:
The vulnerability in Sylius arises due to a mismatch in payment validation during the PayPal Checkout process. When a user modifies the item quantity in their shopping cart after initiating the PayPal Checkout, the updated total amount is not communicated to PayPal. PayPal captures only the initially transmitted amount, while Sylius incorrectly marks the order as fully paid based on the modified total. This discrepancy allows attackers to intentionally or accidentally pay less than the actual order value, leading to financial losses for businesses and compromising the integrity of the payment process. The flaw is rooted in the lack of real-time verification of the payment amount between Sylius and PayPal, enabling exploitation through simple cart manipulation.
DailyCVE Form:
Platform: Sylius
Version: <1.6.1, <1.7.1, <2.0.1
Vulnerability: Payment Manipulation
Severity: Critical
Date: 2023-XX-XX
What Undercode Say:
Exploitation:
1. Steps to Exploit:
- Add items to the cart and proceed to PayPal Checkout.
- Modify the cart (e.g., reduce item quantity) after initiating PayPal payment.
- Complete the payment. PayPal captures the initial amount, while Sylius processes the modified total.
2. Exploit Code Example:
// Simulate cart modification during PayPal Checkout $cart->updateQuantity($productId, $reducedQuantity); $paypal->processPayment($cart->getInitialTotal());
3. Payload Example:
- Initial Total: $100
- Modified Total: $50
- PayPal captures $100, Sylius processes $50.
Protection:
1. Patch Application:
- Update Sylius to versions 1.6.1, 1.7.1, or 2.0.1 and above.
2. Workaround Implementation:
- Override
ProcessPayPalOrderAction,CompletePayPalOrderFromPaymentPageAction, and `CaptureAction` with updated logic to verify payment amounts in real-time.
3. Code Fix Example:
private function verify(PaymentInterface $payment, array $paypalOrderDetails): void {
$totalAmount = $this->getTotalPaymentAmountFromPaypal($paypalOrderDetails);
if ($payment->getAmount() !== $totalAmount) {
throw new PaymentAmountMismatchException();
}
}
4. Service Registration (PayPal 1.x):
services: App\Controller\ProcessPayPalOrderAction: class: App\Controller\ProcessPayPalOrderAction arguments: - '@sylius.repository.customer' - '@sylius.factory.customer' - '@sylius.factory.address' - '@sylius.manager.order' - '@sylius_abstraction.state_machine' - '@Sylius\PayPalPlugin\Manager\PaymentStateManagerInterface' - '@Sylius\PayPalPlugin\Api\CacheAuthorizeClientApiInterface' - '@Sylius\PayPalPlugin\Api\OrderDetailsApiInterface' - '@Sylius\PayPalPlugin\Provider\OrderProviderInterface'
5. Service Registration (PayPal 2.x):
services: sylius_paypal.controller.process_paypal_order: class: App\Controller\ProcessPayPalOrderAction arguments: - '@sylius.repository.customer' - '@sylius.factory.customer' - '@sylius.factory.address' - '@sylius.manager.order' - '@sylius_abstraction.state_machine' - '@sylius_paypal.manager.payment_state' - '@sylius_paypal.api.cache_authorize_client' - '@sylius_paypal.api.order_details' - '@sylius_paypal.provider.order'
6. Prevention Measures:
- Implement real-time payment amount verification.
- Use webhooks to sync PayPal and Sylius payment states.
- Monitor logs for discrepancies in payment amounts.
7. Logging and Monitoring:
$logger->warning('Payment amount mismatch detected', [
'paypal_amount' => $totalAmount,
'sylius_amount' => $payment->getAmount(),
]);
8. Testing the Fix:
- Simulate cart modifications during payment.
- Verify that exceptions are thrown for mismatched amounts.
- Ensure orders are marked as unpaid if discrepancies are detected.
9. References:
- Sylius GitHub Advisory: [bash]
- PayPal API Documentation: [bash]
- CVE Details: [bash]
References:
Reported By: https://github.com/advisories/GHSA-pqq3-q84h-pj6x
Extra Source Hub:
Undercode
