When I try to attach a USB to a pesonal VM, I get an error:
Error: QubesVMError - Domain ‘Windows10’: qrexec not connected
I’ve tried it with Windows 10 and BlackArch Linux so far. They both give the same error. I have a personal VM based on the fedora-30 template, wich I use simply to store some image files. Attaching the USB to that works just fine. It seems to only give an error with VM’s that have an OS installed.
I read this:
Was not able to solve the problem with it. However I do now suspect that this has something to do with missing packages perhaps. I haven’t quite figured out how to manage packages yet either, so I couldn’t really look into that.
Before I updated Qubes you could still see the command line run right up to where you have to type in your hard disk decryption password. I remember noticing an error of some sort that said something about kernel modules not being loaded or something.
USB devices are not supported currently under qubes for windows 10 VMs. See the documentation bellow:
For black-arch it might have to do with missing packages.
My advice in general when getting into Qubes is starting off first with eh default templates and not venturing too much in the first times on advanced stuff and end up really frustrated (like this guy). All of this while qubes can be amazing at its job just with the default templates (it just requires you to get used to fedora and debian).
But if you’re up for the challenges, just go for it.
Also, in terms of pen-testing distributions, kali (debian based) seems to be better supported than the (arch-based) blackarch. I recommend this specific install method (cloning a debian template and dist-upgrade onto kali).
I have to admit, I was not expecting such a trivial feature to not be supported. : xD Adding a USB device to a Windows VM isn’t anything special lol. I’m guessing this has nothing to do with capability, because I can see several devices connected (virtually) in Windows when I’m running the VM. This must be a security thing then?
I’m also quite surprised that creating a VM that is not based on a template is considered advanced haha. I mean, isn’t this exactly what Qubes is meant to do? If you’re full consideration is security then I can imagine that it’s better to use a template, but Qubes can do so much more in terms of practical usage.
Hell I’ve even googled GPU passthrough by now. It’s not a necessity for me on my laptop. It’s really just for work purposes. But I do hope to see this in later versions of Qubes.
Is Adding USB to other VM’s that aren’t based on templates fully supported? Or will that require some tinkering?
From the user perspective it might sound trivial, but not so much in implementation, I’m afraid. Plus, the skillset of the developers is more around linux and xen. Not windows.
But the Qubes team has been on the lookout for a windows developer who can update the too to add this support who’d volunteer to implement this. It’s just that no one has stepped up to do it until, then.
We also have to keep in mind that this is an free software project and the Qubes team is already constrained with anything else. If you have some expertise on windows, feel free to help on that.
I believe this to be for security reasons. Having things based on a template is the secure method of getting update without “application qubes” being able to infect the root partition. Doing things on StandloneVM looses this and other security features.
As far as I’m aware attaching USB to of the available templates should work without anything else. But if you install an OS that’s not yet supported, you’ll have to figure out how to get the packages installed for that.
Dont forget you can create a Windows template, and spin off Windows
appVMs.
If you dont move the UserDirs then you have a rather nice
Windows DisposableVM, which will reset after each use.
It’s not a necessity for me on my laptop. It’s really just for work purposes. But I do hope to see this in later versions of Qubes. 
