[pdkl95]

Implementations are always perfect?

When - not if - someone finds an implementation bug in either the browser or the USB hardware, we will see exploits far worse than keylogging passwords. The bug could be in any USB device, not just the subset you're thinking about. Do you really want to trust your host-controller, every USB device, and the browser interface to be bug free? Are you sure there are no subtle non-bug interactions between devices? Have you even seen how USB devices are designed?

Limitations like "no HID devices" are how it's supposed to work, which is different from how it will actually work.

edit:

Also, did everyone forget about BadUSB?

[justinschuh]

Sorry, but I'm at a loss for what you believe you're responding to here. I made a clear, factual statement regarding the handling of bound USB devices for known devices and classes. Specifically, HID and other native device classes that are already bound by the OS should not be exposed to WebUSB -- the reasons for and robustness of that guarantee should be self-evident to anyone moderately familiar with USB in modern OSes.

Now, if you have a specific argument to make against my statement, then please share it. I have direct experience with the subject here, and ideally can provide context to address such arguments or clear up confusion. However, I really don't think it's productive to respond with non sequitur arguments and personal attacks.

[cm3]

The way USB devices work, they can pretend to be something else and still manage to achieve the ulterior goal. There are some very interesting USB devices on the market which look like one thing, pretend to be something else, and actually are anything but.

[justinschuh]

Mentioning BadUSB very much implies confusion about the threat models at play. That is, the threat model for BadUSB is a malicious device that attacks the host OS, drivers, or applications. Whereas, the threat model for WebUSB is concerned with malicious sites attacking or abusing physical devices attached to the system.

So, the scenario you seem to be implying would require coordination between a malicious WebUSB site and a malicious device. While I can't claim that it would be impossible, it sure seems to approach de minimis if only given the extent of user interactions and preconditions.

[erikpukinskis]

You could say all the same things about every piece of desktop software.