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BLACK HAT - Microsoft seeks tips on virtualization security

BLACK HAT - Microsoft seeks tips on virtualization security

MS talks up its WSV hypervisor-virtualization technology

Microsoft Wednesday for the first time laid out the underpinnings of the security capabilities it has built into its forthcoming Windows Server Virtualization technology, in hopes that researchers will help vet the software, which is expected to ship next year.

The company chose this week's Black Hat conference in Las Vegas to talk about the security inherent in the WSV hypervisor-virtualization technology formerly code-named Viridian.

It will be an add-on to Windows Server 2008, and Microsoft hopes it will offer serious competition to VMware, XenSource, Virtual Iron, Novell and Red Hat in the hot market for virtualization technology.

"As Viridian comes to market, we want to have the security research community engaged in making sure we have a secure product," said Mike Neil, Microsoft's general manager of virtualization.

Neil said WSV was developed as part of the company's Trusted Computing initiative and with its Security Development Lifecycle guidelines, but clearly it's time to get experts to poke and prod the software.

The first public beta, however, is not expected to ship until the end of this year. The finished software is slated to ship within 180 days after Windows Server 2008 is complete, in late December. The server, however, is scheduled to ship on Feb. 27, 2008.

The hypervisor is a thin layer of software that in essence is a microkernel built for reliability. The other virtualization services have been separated off into a root partition.

Microsoft says the hypervisor's role is to provide isolation between guest environments and make sure that operations, such as a security breach in one environment, do not cross over to other guest operating systems running on the hypervisor.

Neil said the overall design and architecture of the hypervisor, which runs directly on the server hardware, is set up so the hypervisor itself is an isolated component within the system (isolation protects all its internal data structures and mechanisms)Â and does not run in the same address space as any other component.

Microsoft's root partition separates the virtualization stack from the core hypervisor layer. The stack houses Windows Management Interfaces and the Virtual Machine Service and its processes, and is also where drivers run.

Microsoft also is tapping into the security features of the virtualization chips from Intel (Intel VT), and Advanced Micro Devices (AMD-V).

Neil said Microsoft is reducing the number of attack vectors by limiting the number of channels between the hypervisor and guest operating systems, excluding general-purpose I/O controls like those found in the Windows driver architecture, banning third-party code from running in the hypervisor, prohibiting memory-sharing among guests, and controlling guest communications through the hypervisor with access controls. In addition, guest operating systems never touch real hardware or devices and have no access to privileged instructions.

In addition, WSV integrates with Microsoft's Authorization Manager for access control and to manage roles, tasks, operations and users.

Microsoft plans to support the next-generation Intel TXT and AMD SVM virtualization chips, and have the hypervisor protect itself against tampering and Direct Memory Access attacks.

Neil also said Microsoft wants to dispel what he called misconceptions introduced at last year's Black Hat around using hardware virtualization to produce invisible rootkits, such as Blue Pill.

"Producing something today that is completely invisible to the rest of the system is very difficult. We don't think it is achievable at this time," Neil said.


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