Qubes 3.2 released


Excerpting information about the new 3.2 “USB passthrough” feature from the announcement blog post:

[…] In Qubes 3.2, we’re also introducing USB passthrough, which allows one to assign individual USB devices, such as cameras, Bitcoin hardware wallets, and various FTDI devices, to AppVMs. This means that it’s now possible to use Skype and other video conferencing software on Qubes! Qubes has supported the sandboxing of USB devices since the very beginning (2010), but the catch has always been that all the USB devices connected to the same USB controller had to be assigned to the same VM. This limitation was due to the underlying hardware architecture (specifically, PCIe and VT-d technologies). We can now get around this limitation by using software backends. The price we pay for this, however, is increased attack surface on the backend, which is important in the event that several USB devices of different security contexts are connected to a single controller. Sadly, on laptops this is almost always the case. Another potential security problem is that USB virtualization does not prevent a potentially malicious USB device from attacking the VM to which it is connected. These problems are not inherent to Qubes OS. In fact, they pose an even greater threat to traditional, monolithic operating systems. In the case of Qubes, it has at least been possible to isolate all USB devices from the user’s AppVMs. The new USB passthrough feature gives the user more fine-grained control over the management of USB devices while still maintaining this isolation. Nonetheless, it’s very important for users to realize that there are no “automagical” solutions to malicious USB problems. Users should plan their compartmentalization with this in mind. We should also mention that Qubes has long supported the secure virtualization of a certain class of USB devices, specifically mass storage devices (such as flash drives and external hard drives) and, more recently, USB mice. Please note that it is always preferable to use these special, security-optimized protocols when available rather than generic USB passthrough. […]


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