PCI Strategy: Avoiding The “Anything But SAQ D” Dilemma

Written by Walter Conway
September 27th, 2011

A 403 Labs QSA, PCI Columnist Walt Conway has worked in payments and technology for more than 30 years, 10 of them with Visa.

As I noted in last week’s column, there is only one problem with the shortened versions of the Self-Assessment Questionnaire (SAQ): They are incomplete. Merchants who qualify for SAQ C process payments on a payment application connected to the Internet. The target audience for SAQ C is small merchants with a payment application on their personal computer, which connects to the Internet to process card transactions. Other requirements are that the merchants store no electronic cardholder data and that their computer is not “connected to any other systems in your environment.”

In the real world, many retailers and franchisors (and franchisees) try to qualify to use SAQ C. I call this the “anything but SAQ D” approach. In my experience, the biggest challenge of SAQ C is isolating the application server(s) from the rest of the merchant environment. I know merchants who have devoted a lot of effort and changed their network so they can qualify for SAQ C. A recent clarification by the PCI Council, however, limits the ability of many retailers and franchisors to use this SAQ.

SAQ C contains 80 questions that cover parts of 11 of the 12 PCI requirements. The sole missing requirement is Requirement 10, informally known as the logging requirement. Allowing a merchant to host a payment application and not requiring logging seems to be a major oversight. I imagine the rationale is that because SAQ C merchants do not store electronic cardholder data, they have no need for audit logs. Maybe this situation goes back to the Council’s original intent that SAQ C would apply to a single person running a payment application on his or her personal computer.

But the reality today is that many sizeable retailers and corporations (i.e., Level 2, 3 and 4 merchants with millions of transactions a year) are using, or trying to qualify for, SAQ C. In my opinion, SAQ C merchants should implement all of PCI’s logging requirements even if they don’t store electronic cardholder data. For example, without logging a merchant would not be alerted if an admin changed the application configuration to store cardholder data or copied that data to his or her laptop.

Another item I would add to my SAQ C list is Requirement 11.5, file integrity monitoring (FIM). Without FIM, merchants hosting a payment application won’t know if a system or application file on one of their POS systems has been compromised. This is critical information needed to achieve a secure operation.

Lastly, although SAQ C includes internal and external vulnerability scanning, it is silent on penetration testing. A security-conscious merchant should include this requirement even though it does not appear on the SAQ. The bad guys are regularly scanning and testing merchants’ systems. At least with a pen test those merchants get to see the report of their vulnerabilities and, hopefully, correct them.

SAQ C-VT (the VT stands for “virtual terminal”) is new in PCI 2.0. It includes 51 questions covering parts of nine of the 12 PCI requirements.


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