Flaws in the Carbon Layer: Is a Penetration Test Without a Social Engineering Component Really a Penetration Test?

Written by Walter Conway
June 3rd, 2013

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

Every QSA gets asked the same question about penetration testing: What is acceptable (translation: what is the least I can do) for PCI compliance? In the current environment of criminal (and state-sponsored) hacking, that is the wrong question. Instead retailers should ask: How do I get the greatest value from the penetration testing I am already required to do? I would like to make the point that at least part of the answer is for every retailer and payment card merchant to include some form of social engineering as a part of their pen testing.

PCI DSS Requirement 11.3 has a lot of detail on when retailers need to conduct pen tests. It recommends, for example, “at least annually and after any significant changes to the environment.” In practice, this means retailers need to perform and/or re-perform pen testing after such events as upgrading their operating system, adding a sub-network to the Cardholder Data Environment (CDE), or even adding a Web server to the CDE.

However, the requirement does not specify details on what the pen test should cover other than it should include “network-layer” and “application-layer” testing.

Retailers also have flexibility on their choice of whom to use to conduct the pen test. The only requirements for the actual individual(s) conducting the pen test are that they be “qualified” and have “organizational independence.” In practice, this means that the pen tester does not have to be a QSA or even from a QSA company at all. The pen tester can be from an outside security firm. Many merchants with substantial IT and security resources use internal staff to conduct the required pen testing.

Naturally, when the QSA comes in for the annual assessment, she or he will need to confirm the tester’s independence and qualifications. Testing independence means identifying where the pen tester sits in the organization (if an internal resource) or whether the tester has or had any involvement in implementing or maintaining the CDE. Testing qualifications is a bit trickier. The tester should have evidence of training and experience using the myriad pen testing tools.

Your QSA will also need to review the pen test report (yes, the QSA needs to see a pen test report even if internal staff conducts the test) for thoroughness and to confirm that exploitable vulnerabilities that the tester identified were corrected and retested. This last step is accomplished by a second round of testing to confirm the vulnerability is no longer present.

It seems particularly unfortunate to me that the phrase “social engineering” appears nowhere in the PCI DSS. Even more unfortunate, my recent search on the term in the PCI Knowledge Base came up blank as well. This situation is particularly disappointing because social engineering attacks are increasingly frequent and very often effective against retailers.

At its simplest, social engineering involves manipulating individuals to take an action (e.g., click on an attachment containing malware) or divulge confidential information (e.g., a password). In a social engineering attack, the call center or help desk staffer, for example, is manipulated into resetting an account, or the recipient of the phishing email is convinced the attachment is really of interest to their career.

Why should social engineering be a crucial element in every retailer’s pen testing?



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