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AnonTechie writes:

On Wednesday, at the RSA conference in San Francisco, Microsoft veep Scott Charney outlined a new security mechanism in Windows 10 called Device Guard ( https://blogs.windows.com/business/2015/04/21/windows-10-security-innovations-at-rsa-device-guard-windows-hello-and-microsoft-passport/ ). We've taken a closer look.

The details are a little vague – more information will emerge at the Build event next week – but from what we can tell, Device Guard wraps an extra layer of defense around the operating system to prevent malware from permanently compromising a PC.

Device Guard, when enabled by an administrator, checks to see if each and every application is cryptographically signed by Microsoft as a trusted binary before it is allowed to run. Device Guard itself runs in its own pocket of memory with its own minimal instance of Windows, and is protected from the rest of the system by the IOMMU features in the PC's processor and motherboard chipset.

These IOMMU features (outlined here by the Minix project http://www.minix3.org/docs/szekeres-iommu.pdf ) wall off Device Guard from the computer's hardware, so it cannot be tampered with by other software, no matter how low level that software is.

If the Windows 10 kernel, which has control over the PC, is compromised, Device Guard will remain fire-walled off, and cannot be subverted into allowing unauthorized code to run. A hypervisor running beneath the kernel and Device Guard enforces this.

(In theory, that is – similar "secure execution environments" have been defeated in the past.)
http://atredispartners.blogspot.com/2014/08/here-be-dragons-vulnerabilities-in.html
http://blog.azimuthsecurity.com/2013/04/unlocking-motorola-bootloader.html

http://www.theregister.co.uk/2015/04/23/microsoft_windows_10_device_guard/

Do you think that Microsoft can make this work as described?