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Development => PC, Mac & Vintage Computers => Topic started by: Juju on July 22, 2018, 06:13:09 am

Title: Doing something interesting with a Windows RT tablet
Post by: Juju on July 22, 2018, 06:13:09 am
Well, one time a few years ago, I bought a Windows RT tablet to my grandma so she can do her stuff with Microsoft Word and go on Internet and stuff. Don't need the Pro version, I thought.

Well, guess, what, I was wrong. I have almost nothing installed on it and, with time and updates, Windows ate all of the measly 32 GB of storage installed on it. It went highly unstable, with nothing you can uninstall or delete to fix it. So my grandma sent it back to me in hopes I could fix it and do something interesting. I did a lot of stuff on it before, and they mostly all failed so far, or I didn't had time to investigate deeper. And anyway, it should have run out of support as of now. So, this is the update log thread.

Well obviously, we can do some hacks to unlock whatever feature to get a bit more control, unlock Secure Boot or something, or something of that ilk. But first, we can try to disable BitLocker, which isn't something you can do on those. It's actually required so these hacks would go smoothly without fear it would turn it into a brick.

This article (http://www.theregister.co.uk/2016/07/15/windows_fix_closes_rt_unlock_loophole/) suggests Microsoft patched a vulnerability disabling a backdoor into Secure Boot. And from a look of it, this update looks installed. They still provide a good command to disable BitLocker:

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manage-bde -protectors C: -disable
Invalid namespace, they say. Looks like the WMI namespace got somehow deleted. Let's reinstall it.

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cd C:\Windows\System32\wbem
mofcomp.exe win32_encryptablevolume.mof

Oh, it worked. Let's try the manage-bde one again... Also worked.

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manage-bde -status
And it's unlocked. Next a reboot for good measure, and it should theorically be disarmed. Somehow. I'm not sure.

Next step would probably to reinstall it with the recovery partition, possibly downgrade it, unless someone have a better idea. To be continued...

On that note, thanks @gameblabla on Discord for the help!
Title: Re: Doing something interesting with a Windows RT tablet
Post by: gameblabla on July 22, 2018, 12:21:33 pm
It seems like GRUB is as far as you gonna get...
https://forum.xda-developers.com/windows-8-rt/rt-development/wip-secure-boot-linux-surface-rt-t3653848 (https://forum.xda-developers.com/windows-8-rt/rt-development/wip-secure-boot-linux-surface-rt-t3653848)
Never trust headlines... I really thought someone would whip up a basic Linux ARM distribution but i guess no one attempted such as thing !They did however manage to disable secure boot.
However, it would help to know the hardware behind it. I guess you could try booting an upstream kernel with grub and compile your own userspace with buildroot but that basically requires, well, doing almost everything from scratch.
There's also WinEmu (now abandonned) that allowed running x86 WIndows apps on jailbroken Windows RT devices.Point is, make sure it's Windows RT 8.0 and not 8.1.
Title: Re: Doing something interesting with a Windows RT tablet
Post by: Juju on July 23, 2018, 03:19:34 am
Correct me if I'm wrong, looks like no one got a kernel working yet. Once done, it's kinda easy to get any ARM distro working too.