I’ve been following the developments on the home-brew front for Windows RT for the past few months. As you’ve probably heard, a “jailbreak” for Windows RT was documented several days ago. This “jailbreak” allows the user to run desktop applications that are not signed by Microsoft. You can ready more about how the exploit works here.
The original exploit was pretty difficult to do and involved using a combination of a Windows Store app to open a command prompt that is then able to run some unsigned applications, and then using that command prompt to exploit a bug in Windows RT that stores a new value in memory used when checking if an app is signed. The actual exploit also required the user to use remote debugging from VS2012 in order to get the exploit payload into memory on the Windows RT device and then setting several breakpoints, redirecting the RT device to that payload in memory. Yikes. This mostly just led me to BSOD my device repeatedly.
However, a couple of days ago a much simpler jailbreak tool was released that just involves a double-click and following a few prompts. You can read about the tool and download it here.
Once you have Windows RT able to run unsigned desktop apps you can download a whole set of FOSS apps that have been recompiled for ARM such as Notepad++, PuTTY, bochs, and 7-Zip. The list is growing daily, and there’s even an app you can install on Windows RT that makes for a non-official “RT Desktop Store”.
One of the very cool and often overlooked aspect of all this, though, is that any pure .NET 4.5 application will also run on Windows RT once jailbroken. I tested this myself and it worked without any extra steps. I created a new C# .NET 4.5 application and was able to run it, unmodified, on my Surface RT.
Microsoft has stated that they do not see the current jailbreak as a security vulnerability, though they could also (obviously) not promise that the exploit will remain unpatched. If you want to ensure your device remains “vulnerable” there are steps to disable automatic updated for Windows RT here.