Feeds

Windows RT jailbreak smash: Run ANY app on Surface slabs

No need for Microsoft's software store

Security for virtualized datacentres

The security mechanism preventing unauthorised software running on ARM-powered Windows RT tablets - such as Microsoft's Surface slabtops - can be easily defeated.

The Redmond giant wanted only cryptographically signed executables, ideally those obtained from the official Windows application store, to run on its hardware. But, we're told, by twiddling a byte of memory in the Windows kernel, it is possible to disable the protection system and allow any code to run on the system.

Taking full control of the device, effectively jail-breaking the computer to run any desktop or touch-driven ARM-compatible software, is an exercise left to the user.

A security researcher calling him or herself C. L. Rokr claims to have found an oversight in the Windows kernel to allow this to happen. According to Rokr, all you have to do is fire up the Windows Debugger software with Administrator-level permissions, connect it to the tablet and manipulate the device's kernel memory.

Specifically, one needs to inject a blob of ARM code into a safe spot of RAM and have the Windows RT kernel divert the processor momentarily to run these instructions. This code locates and alters a moderately hidden variable in the kernel to disable the executable signature check. On PCs the variable contains '0' allowing any program to run, whereas it is '8' on Windows RT devices to enforce the signature check.

Trivially overwriting this byte can therefore change the level of protection on the system and circumvent Microsoft's cryptographic keys.

You can read more about the hack along with a how-to guide here.

Windows RT, which is a straight-up ARM port of Windows 8 for portable computers, was built to only run apps that are signed using a Microsoft-issued certificate.

The hack is unlikely to be something most non-techie users could pull off as it requires knowledge of WinDbg. And modifying the operating system could fall foul of the device's secure boot protection, which refuses to start the OS if it has been altered.

It's also not clear which apps can be run, although as pointed out in this programming forum the software must be compiled for, or otherwise be compatible with, ARM-powered systems. Programs already built for Intel and AMD processors need not apply, therefore.

Windows RT can be found on Microsoft's Surface tablet and fondleslabs from companies including Asus and Samsung. So far it appears sales of Windows RT devices are low and below Microsoft's expectations. Redmond has quickly turned from only selling Surface itself online and in its stores to recruiting retail partners.

One reason for the lack of interest could be lack of apps. Windows RT has been deliberately locked down because, we're told, Microsoft wants to maintain a standard of performance and security, and to ensure apps conform to the design of the interface and input via touch. This means the number of Windows RT apps is far behind the number of apps that exists for Intel machines running the exact same operating system.

Devices using Windows RT come with some built-in apps including Office Home and Student 2013 RT Preview Edition and Mail, Messaging and SkyDrive, but the official way to obtain more is via Microsoft's Windows Store, which supplies suitably signed executables. ®

Beginner's guide to SSL certificates

More from The Register

next story
Microsoft on the Threshold of a new name for Windows next week
Rebranded OS reportedly set to be flung open by Redmond
Business is back, baby! Hasta la VISTA, Win 8... Oh, yeah, Windows 9
Forget touchscreen millennials, Microsoft goes for mouse crowd
SMASH the Bash bug! Apple and Red Hat scramble for patch batches
'Applying multiple security updates is extremely difficult'
Apple: SO sorry for the iOS 8.0.1 UPDATE BUNGLE HORROR
Apple kills 'upgrade'. Hey, Microsoft. You sure you want to be like these guys?
ARM gives Internet of Things a piece of its mind – the Cortex-M7
32-bit core packs some DSP for VIP IoT CPU LOL
Lotus Notes inventor Ozzie invents app to talk to people on your phone
Imagine that. Startup floats with voice collab app for Win iPhone
'Google is NOT the gatekeeper to the web, as some claim'
Plus: 'Pretty sure iOS 8.0.2 will just turn the iPhone into a fax machine'
prev story

Whitepapers

A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.
Storage capacity and performance optimization at Mizuno USA
Mizuno USA turn to Tegile storage technology to solve both their SAN and backup issues.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Beginner's guide to SSL certificates
De-mystify the technology involved and give you the information you need to make the best decision when considering your online security options.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.