Sylius, Payment Process Manipulation, CVE-2023-XXXX (Critical)

How the CVE Works:

The vulnerability in Sylius allows users to manipulate their shopping cart after completing the PayPal Checkout process and payment authorization. When a user initiates a PayPal transaction from a product or cart page and returns to the order summary page, they can alter the cart contents before finalizing the order. This discrepancy between the order amount in Sylius and the amount captured by PayPal can result in merchants delivering products or services without receiving full payment. The flaw arises due to insufficient validation of the cart contents post-payment authorization, enabling attackers to exploit the payment flow.

DailyCVE Form:

Platform: Sylius
Version: <1.6.2, <1.7.2, <2.0.2
Vulnerability: Payment Manipulation
Severity: Critical
Date: 2023-XX-XX

What Undercode Say:

Exploitation:

1. Exploit Workflow:

Initiate a PayPal transaction from the product or cart page.
Return to the order summary page before finalizing the order.
Modify the cart contents to reduce the payment amount.
Complete the order with the manipulated amount.

2. Exploit Code:

// Simulate cart manipulation post-payment authorization
$order = $cart->getOrder();
$order->setTotal($manipulatedAmount);
$payment = $order->getLastPayment();
$payment->setAmount($manipulatedAmount);

3. Payload Example:

Original Cart Total: $100
Manipulated Cart Total: $50
PayPal Capture: $50
Sylius Order Total: $100

Protection:

1. Patch Implementation:

Update Sylius to versions 1.6.2, 1.7.2, or 2.0.2 and above.

2. Workaround Code:

Override `PayPalOrderCompleteProcessor` to validate payment amounts:

private function verify(PaymentInterface $payment): void
{
$totalAmount = $this->getTotalPaymentAmountFromPaypal($payment);
if ($payment->getOrder()->getTotal() !== $totalAmount) {
throw new \Exception('Payment amount mismatch');
}
}

3. Service Registration for PayPal 1.x:

Sylius\PayPalPlugin\Processor\PayPalOrderCompleteProcessor:
class: App\Processor\PayPalOrderCompleteProcessor
arguments:
- '@Sylius\PayPalPlugin\Manager\PaymentStateManagerInterface'

4. Service Registration for PayPal 2.x:

sylius_paypal.processor.paypal_order_complete:
class: App\Processor\PayPalOrderCompleteProcessor
arguments:
- '@sylius_paypal.manager.payment_state'

5. Additional Checks:

Implement server-side validation to ensure cart contents cannot be modified post-payment authorization.
Log discrepancies between PayPal capture amounts and Sylius order totals for auditing.

6. Monitoring Commands:

Use the following command to monitor payment discrepancies:
```
php bin/console sylius:paypal:audit-payments
```

7. Automated Testing:

Write unit tests to verify payment amount consistency:

public function testPaymentAmountConsistency()
{
$payment = $this->createPayment(100);
$this->assertEquals(100, $payment->getAmount());
}

8. Security Recommendations:

Regularly audit payment processing workflows.
Implement real-time alerts for payment discrepancies.
Educate merchants about the risks of unpatched systems.
By following these steps, you can mitigate the risk of payment manipulation and protect your Sylius-based e-commerce platform.

References:

Reported By: https://github.com/advisories/GHSA-hxg4-65p5-9w37
Extra Source Hub:
Undercode

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