Evan Schuman's StorefrontBacktalk

Guest Columnist David Taylor is president of the PCI Alliance and a former E-Commerce and Security analyst with Gartner.

Virtualization technology has been around for a while, although interest in it has largely been confined to the seriously geeky among us. The primary benefits of virtualization are flexibility and scalability. It allows a company to "pool" computer hardware and create new applications, new servers, new networks, new data storage at the touch of a button and, in the process, reduce costs and administrative overhead.

Standards lag technology: Recently, as we’ve been talking to retailers for the PCI Knowledge Base project, we have heard several reports where retailers found themselves on the wrong side of the PCI Standards because they implemented virtualized servers within their cardholder environment. At issue is PCI security standard 2.2.1, which says that a server is only allowed to have "one primary function."

Essentially, PCI standards do not address the technology of virtualization. In addition, PCI assessors are not currently being given training on how to assess virtualized servers.

We’ve talked with a dozen assessors on our Panel of Experts about it. Some say "a box is a box is a box" – which can greatly increase the scope of your PCI audit if the "box" in question is a mainframe (where virtualization got its start over 30 years ago) or a large Linux or Unix server. Others say that virtualization is a type of compensating control, like network segmentation, and actually helps companies decrease the scope of a PCI audit.

The point is simple: While virtualization can significantly reduce your IT hardware and management costs, it can broaden the scope of a PCI audit and potentially cause you to fail, unless all the applications, databases, access controls and communications functionality on a virtualized server comply with the PCI standards. But, however you use virtualization, you will still have to "prove" that there are sufficient controls in your virtual environment to your assessor.

Time to go PCI assessor shopping: Since there is no official guidance on how to assess virtualized environments, the best recommendation we can make for getting you safely through a PCI assessment is to interview about a half dozen assessors regarding their positions on (and experience with) server virtualization, and do some homework on how to secure virtualized environments.

The bottom line: There is no good reason to avoid deploying virtualized servers and applications in the cardholder environment if you have good documentation of the controls (if you’re doing a self-assessment) or work with an assessor who understands the security controls that are available and how to deploy them effectively. If you want to discuss this column or any other security or compliance issues, please send me an E-mail at David.Taylor@PCIAlliance.org or visit www.KnowPCI.com to join the PCI Knowledge Base.