Microsoft has quietly killed a vulnerability that can be exploited to unlock ARM-powered Windows RT tablets and boot non-Redmond-approved operating systems.
The Register has learned that one of the security holes addressed this week in the July edition of Microsoft's Patch Tuesday closes a backdoor left in Windows RT by its programmers during its development.
That backdoor can be exploited to unlock the slab's bootloader and start up an operating system of your choice, such as GNU/Linux or Android, provided it supports the underlying hardware.
Normally, Windows RT devices are locked down to only boot software cryptographically signed by Microsoft. That's left some Windows RT owners frustrated because they're unable to switch to another OS: the firmware refuses to accept non-Microsoft code, and curious minds have been trying for years now to defeat these defenses and run whatever they want. The bootloader cannot be unlocked even if you have administrator-level access on the device.