Vulnerability Allowing Hacker to Bypass Checkout Process Using PayPal Bill Me Later Payment Method

[nicolasddev]

Preconditions and environment

• Magento version 2.4.5-p5
• Enable the PayPal Bill Me Later payment method.
• Disable all offline payment methods.

Steps to reproduce

Attempting to place an order using the PayPal Bill Me Later payment method, without actually providing any payment information.

We were unable to reproduce this exploit during our testing.

Expected result

The order cannot be placed without providing valid payment information.

Actual result

The hacker is able to place an order without providing valid payment information.

Additional information

Although no offline payment method is enabled, hackers are successfully able to place orders without providing any payment information. This vulnerability has been abused multiple times and the paypal_express_bml payment method was used to place these orders. Since no offline payment method is enabled, the hacker would normally have to resort on carding attacks in order to bypass the checkout process without providing valid credit card information. However, with the reCAPTCHA protection in place, carding attacks would be limited to only a few attempts. Therefore, it appears that the hacker is using this method to work around the standard checkout process and place dummy orders.

All of these orders were placed from various IPV6 addresses and contained code injection patterns similar to those reported in the issue #39002.

It is worth noting that, aside from the fact that the registered payment method was paypal_express_bml, the payment information was completely missing.

Release note

No response

Triage and priority

• [X] Severity: S0 - Affects critical data or functionality and leaves users without workaround.
• [ ] Severity: S1 - Affects critical data or functionality and forces users to employ a workaround.
• [ ] Severity: S2 - Affects non-critical data or functionality and forces users to employ a workaround.
• [ ] Severity: S3 - Affects non-critical data or functionality and does not force users to employ a workaround.
• [ ] Severity: S4 - Affects aesthetics, professional look and feel, “quality” or “usability”.

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