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These new chips will have what AMD's McDowell calls a "device exclusion vector" that can authorize or block hardware access to VMs, as well as create a chain of permissions that flow from one device to another, so OS and hypervisor developers can control not only what hardware can do what, but also what flows among hardware devices are permitted. McDowell expects this approach to prevent the subsystem-as-spy problem that both it and the NSA identified.

Virtual Layers Add Security

While virtualization is used commercially to have multiple operating systems run on one machine (to get more usage from physical servers, to run Windows on Macs, and to easily set up testbed environments) its origins trace back to a military security need. In fact, the VMware technology that popularized virtualization is a spin-off of Defense Department-sponsored research done at Stanford University; the military saw early promise in virtual machines to encapsulate networks and desktops from outside threats, resulting in an NSA-created OS called NetTop that in 2001 did for Linux what products such as Parallels Desktop and VMware Desktop do today: provide separate VMs that can't affect each other on one box.

Now the NSA sees virtualization protecting systems in a new layering approach, Simard said. The idea is to have an independent layer handle security, so even if an OS has security flaws, a separate layer that the OS can't compromise handles security threats such as viruses and worms or implements firewalls. Simard said it's inevitable that PC operating systems will have security holes: "The PC platform is a very feature-rich platform, and being feature-rich gets it into trouble."

The NSA, working with General Dynamics and IBM, has developed the first version of this technology, which it calls the High Assurance Platform workstation, for the U.S. Special Operations Command, using VMware, Novell SuSE Linux, and Red Hat Linux, Simard said.

"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.