Vuln in Verisign PayFlow Link payment service

["Keith Royster" <keith () theroysters com>]

Hello!  I'm very new to this list and am looking for advice on how and where
to properly post information regarding a vulnerability I have identified
with Verisign's PayFlow Link credit card payment service.  I would
ultimately like for this information to get into the Vuln Database at
BugTraq, but do not know the proper procedures and requirements for getting
it there. Below is a brief(?) description of the service and the exploit...

THE SERVICE: The final checkout page of various online shopping cart
applications presents the shopper with a form asking for credit card acct#,
exp date, etc.  When the shopper submits the form, the data is sent directly
to the vendor's PayFlow Link account at Verisign for validation.  If the
credit card information if validated, Verisign authorizes payment and
submits the data back to the vendors shopping cart application.  When the
vendor's shopping app receives this data, it assumes payment was authorized
and finalizes the order for the vendor to fill and ship it.

EXPLOIT #1: On the final checkout page, save the HTML to disk and edit the
ACTION= portion of the form to direct the data back at the shopping cart
instead of to verisign.  The exact URL should match that which verisign
would submit a validated order to.  Save the edited HTML, reload in your
browser, and submit bogus credit card info with your order. Since there is
no authentication between Verisign and the shopping application, the
shopping app will think that the card was authorized, and so it will
finalize the order.

EXPLOIT #2: Sign up for a free demo PayFlow Link account at Verisign.  While
in demo mode, this account will "validate" almost any credit card info
submitted to it.  This account should be configured to send the confirmation
information to the exploitee's shopping system.  Then perform a similar HTML
edit of the final checkout page as above, only this time change the hidden
form tag to direct the payment to your demo PayFlow Link account. Save the
HTML, reload in your browser, and submit bogus credit card info.

THE RISK: Vendors that do no validate payment in their Verisign acct prior
to shipment, or those that offer immediate downloads of software upon
payment, are vulnerable to theft.

WHAT I KNOW:  I have successfully performed both exploits on a Miva Merchant
3.x shopping cart.  I have not had the opportunity to test other shopping
cart applications or other versions of Merchant.  I have communicated this
information to both Miva and Verisign.  Verisign tested and confirmed both
exploits as well.  They then responded that they do not intend to fix it -
that instead they will educate their customers regarding the risks and
encourage them to upgrade to the more secure (and costly) PayFlow Pro
product.

WHAT I DON'T KNOW: I don't know what other shopping cart applications (if
any, besides Miva's) are vulnerable.  But I am highly suspicious that others
are.  I also have not verified any other version of Miva Merchant besides
3.x. Merchant 4.x is the most current version, but I think it's PayFlow Link
module is the same and so it should be vulnerable as well. I would be
interested in working with others that have access to other shopping cart
apps that can interface with PayFlow Link.

TIA!