Granted the virtual desktop distributes no data to the locale of the end user. In what other ways is the virtual desktop more secure today than it was before? A view into what's being done was offered by Ian Pratt and Air Force researcher Ryan Durante in a Synergy session May 26. Pratt is the Cambridge University professor who deciphered the x86 instruction set for the Xen open source hypervisor. He did so after Mendel Rosenbloom had accomplished that feat in the U.S., so he sometimes gets less recognition than the founder of VMware, but I doubt if the small amount of time separating their respective efforts made the job any easier.
The Air Force is part of the DOD effort to come up with a secure desktop and Durante, chief of the cross-domain solutions and innovation section of the Air Force Research Laboratory, says it is seeking to virtualize its desktops in a manner similar to that of the Defense Intelligence Agency. Pratt has been the lead liason with the Air Force Research Laboratory work in that effort and the pair hosted the session on XenClient security. If the Air Force's version of a virtualized end user desktop is convincingly secure, it will be used as a model for adoption throughout the Department of Defense, Durante says.
Pratt joined Citrix as VP of advanced products when it purchased XenSource, the company behind the Xen hypervisor. He's using, as might be expected, XenClient XT, the version also announced May 25 that makes use of Intel's trusted boot process for the hypervisor. If someone has modified the virtual machine, the Intel TXT checking will detect it and kill off the boot. The process makes it difficult for an intruder to get any spyware or system alterations planted on a virtual machine. It's available with motherboards built with Xeon 5600 chips.
XenClient is a Type 1 hypervisor that enforces strict isolation on each virtual machine, so different types of virtual machines may run on one client without risking exposure to each other. Likewise, different networks are each booted in their own VMs and run alongside each other without intruding on or compromising each other's traffic, even if one has a much lower security rating than the other, Pratt said in an interview at the end of the May 26 session.
If a virtual machine were in some way compromised on a user device, the fact that the network is in its own virtual machine prevents the malady from spreading to other VMs, Pratt says. Pratt also says XenClient relies on Pascal and other research languages more than the C family, often used in the world of PC exploits. "Another key technical barrier is the narrow interfaces between XenClient components," he says. A strictly defined interface between, say, the hypervisor and client network controller offers a smaller attack surface. The interface can also be inspected quickly for integrity.
Citrix is clearly using these security features as credentials for secure operations in the larger corporate market. It is expanding the usefulness of XenClient by giving it a companion piece of client software that adapts to different devices, allowing the same XenClient virtual machine to run on each. That added piece is Citrix Receiver.
Think of Citrix Receiver as the software that does for XenClient what the Java Virtual Machine did for Java. To meet Sun's boast of having a write once, run anywhere language, it needed to create a virtual machine environment that could be written for individual hardware devices. The JVM differed from machine to machine, but the Java compiled code could run in any JVM. Likewise, a version of Citrix Receiver can be created for different PCs, tablets, and smartphones but run the same virtualized desktop in each. So far, Receiver runs on 1,000 different PC models, 149 smartphone, 37 tablets, and 10 different thin clients. There's a Receiver for Apple iOS, Google Android, HP's webOS and Google ChromeOS. So far, the Apple iPad, HP TouchPad, Blackberry Playbook and Google Chromebook are covered, along with a many laptops and PCs.
Many problems of end user virtualization remain to be worked out. But if virtual desktops provide secure computing for wide ranging Defense Intelligence Agency staffers, they may be the answer for highly mobile enterprise workers as well. Desktop virtualization in a new secure form is about to emerge, and it may help not only the DIA but those IT managers perpetually under siege as well.
Charles Babcock is an editor-at-large for InformationWeek.
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