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by DeathArrow 142 days ago
Probably there is someone somewhere trying to make Linux boot on a thunderbolt cable.
2 comments

It would be a pretty amusing demonstration to plug in the cable to a display, then pretend to plug the other end into an imaginary computer sitting nearby and have something boot up on the display.
It'd be a cool physical demonstration at a cybersecurity roadshow.

A concern: with all this computing onboard, does this mean a malicious USB-C cable could record screen and keystroke?

Often the keyboard receiver is plugged into the monitor's USB hub and so screen and HID are both going along a single cable ... Which also does power delivery. Such cables are a definite "sales category" and could be a target for supply chain attacks. But if they now have chips onboard, doesn't that mean an attacker could even takeover a genuine cable? It seems like a real risk tbh.

> A concern: with all this computing onboard, does this mean a malicious USB-C cable could record screen and keystroke?

Keystrokes: Easily. At least for USB 3 and 4, USB 1/2 data is a physically separate channel that just happens to almost always be packaged alongside the faster stuff, so the lower speed stuff like input devices is easy to intercept. I don't know if Thunderbolt does the same or not, normally USB-C alternate modes still keep the USB 2.0 signals available but Thunderbolt might be an exception.

Screen: Probably not modern video modes in a purely stealthy cable formfactor *YET*, at least not using COTS parts, but it wouldn't surprise me to find the secret squirrel types either already have it or are working on it.

I doubt you are going to fit a chip fast enough to snoop Thunderbolt traffic inside of a usb-c plug
Today, but maybe not much longer.

It is possible that the tech exists, but isn't yet at a point that it can be easily mass-produced, which means "spy cables" may actually be available, from Q-types.

I think Think Geek used to have a "frayed cable" usb drive... and there have been "how to" for one such as https://www.evilmadscientist.com/2008/how-to-make-a-sawed-of...
Or Doom.
Was going to say the same thing. With way more processing power you could output the video over USB-C/TB at one end and connect a keyboard at the other.