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Blocking Untrusted USB Devices

roussos.cc

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Re: Blocking Untrusted USB Devices

#2
How immune is this solution to VID / PID spoofing?

I've thought about this topic before and arrived at the idea that USB devices ought to be treated kind of like user accounts, where I can control what drivers / data / devices they have access to.

Re: Blocking Untrusted USB Devices

#4
post #2

How immune is this solution to VID / PID spoofing? I've thought about this topic before and arrived at the idea that USB devices ought to be treated kind of like user accounts, where I can control what drivers / data / devices they have access to.

If the USB device can proffer a spoofed ID, there is no auth a-la PKI. Maybe there is a USB controller where it is possible to turn off the data lanes and only keep the power ones active, but short of that, USBGuard had to trust the ID of the device. Raspberry Pi Zero's USB controller, AFAIK, had the ability to present itself as a target, so that seems like a quick experiment.

Re: Blocking Untrusted USB Devices

#5
post #4
post #2

How immune is this solution to VID / PID spoofing? I've thought about this topic before and arrived at the idea that USB devices ought to be treated kind of like user accounts, where I can control what drivers / data / devices they have access to.

If the USB device can proffer a spoofed ID, there is no auth a-la PKI. Maybe there is a USB controller where it is possible to turn off the data lanes and only keep the power ones active, but short of that, USBGuard had to trust the ID of the device. Raspberry Pi Zero's USB controller, AFAIK, had the ability to present itself as a target, so that seems like a quick experiment.

Thanks! One benefit of the approach I envisioned above is that even a perfect imposter would be restricted to the access rights I granted the original device.

Re: Blocking Untrusted USB Devices

#6
post #5
post #4

Earlier quoted context omitted.

If the USB device can proffer a spoofed ID, there is no auth a-la PKI. Maybe there is a USB controller where it is possible to turn off the data lanes and only keep the power ones active, but short of that, USBGuard had to trust the ID of the device. Raspberry Pi Zero's USB controller, AFAIK, had the ability to present itself as a target, so that seems like a quick experiment.

Thanks! One benefit of the approach I envisioned above is that even a perfect imposter would be restricted to the access rights I granted the original device.

Take a look at USB Rubber Ducky or similar device(s). HackADay [1] [2] has a couple of write-ups about it and some associated tools.

[1]https://hackaday.com/2019/02/12/a-malicious-wifi-backdoor-in...

[2]https://hackaday.com/2014/10/05/badusb-means-were-all-screwe...

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