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I probably didn't help in describing the idea clearly, but who do you mean by "which you host"? My thought process was that it would work like this: Merchant

by lftl 16y ago

I probably didn't help in describing the idea clearly, but who do you mean by "which you host"? My thought process was that it would work like this: Merchant - Hosts a a payment form, but it POSTs to the service's server basically <form method="post" action="https ://someservice.com"> Service - Receives the POST and forwards it on to Auth.NET, Paypal Pro, or whoever the Merchant is using to process transactions. The user is redirected back to merchantwebsite.com with appropriate response data. Are you saying the merchant website would still need to be PCI compliant or just the Service's? I definitely understand that the service would have to be PCI compliant. But it seems like it'd be a valuable service for a number of small e-commerce providers to essentially outsource online PCI compliance with minimal downside. EDIT: While I haven't used them, my understanding is that Braintree offers pretty much exactly this service, except that they require that they provide your merchant account and act as your payment processor.

tptacek 16y ago
While I can go for hours talking about the actual technical risks here, I'm less firm about how a PCI auditor is going to interpret any specific thing you do. We don't PCI audit; we find and fix vulnerabilities in software. Having said that: The technical risk of you hosting HTML that POST's via HTTPS somewhere else is that any input that influences any dynamic component of the page on which the form is hosted could alter the "action" attribute of the form to point somewhere else, without it even being detectable in the page source. You can say that about any chain of pages, including in-app page flows all the way through Google SERPs, but it's a particularly severe risk on the actual page that asks for the credit card number, since there are no macro-level cues a user has as to whether the page is valid or not. OWASP is making more noise about things like "insecure redirects" for, among other things, this exact scenario. Expect the "host the HTML FORM that asks for the credit card number and send it to the payment processor" technique to run afoul of PCI DSS any year now.

by lftl 16y ago

tptacek 16y ago

While I can go for hours talking about the actual technical risks here, I'm less firm about how a PCI auditor is going to interpret any specific thing you do. We don't PCI audit; we find and fix vulnerabilities in software. Having said that: The technical risk of you hosting HTML that POST's via HTTPS somewhere else is that any input that influences any dynamic component of the page on which the form is hosted could alter the "action" attribute of the form to point somewhere else, without it even being detectable in the page source. You can say that about any chain of pages, including in-app page flows all the way through Google SERPs, but it's a particularly severe risk on the actual page that asks for the credit card number, since there are no macro-level cues a user has as to whether the page is valid or not. OWASP is making more noise about things like "insecure redirects" for, among other things, this exact scenario. Expect the "host the HTML FORM that asks for the credit card number and send it to the payment processor" technique to run afoul of PCI DSS any year now.