"I believe strongly in doing antivirus and firewalling in isolation outside the OS," said AMD's McDowell. But Simard is concerned that this layered approach could compromise security if poorly implemented in commercial systems. The reason: If the security layer is compromised, such as through poor design, then an intruder now has access to all the VMs on the system. McDowell agreed with that concern, saying that such a layered approach can't replace security at the OS and network -- instead it must supplement those components' security. He also noted that applications are the most common route for vulnerabilities to find their way into an OS, so they too need to have their own protection mechanisms.

A related concern is the hypervisor, the root layer that manages the VMs. If compromised, it could expose everything on the system. But McDowell is least worried about this scenario: "Hypervisors are very hard to write, and there are just three of them -- Xen, Microsoft, and VMware" -- so there's not broad expertise for hackers to tap into, he said.

The leapfrog effect
Citrix's Roemer noted that the NSA's risk examples are on the extreme side. "They're onto something there, but a lot of their needs greatly exceed that of other organizations, he said.

The NSA's Simard agreed, but noted that there's a leapfrog effect, in which the NSA and other government agencies sometimes are the first to come across a threat, and feed that experience to commercial companies to help them improve their products. The commercial companies take the issue a step further and end up having better options than the government, which then pushes the envelope in its usage and discovers new issues.

He sees this being very true in the virtualization world, where the feds were the first to see the technology as a security aid and then, more recently, as a new potential threat vector. "Hopefully, industry will learn from our worries," Simard said.