> how does one defend against an attacker or red-team who controls the CPU voltage rails
The xbox does have defences against this, the talk explicitly mentions rail monitoring defences intended to detect that kind of attack. It had a lot of them, and he had to build around them. The exploit succeeds because he found two glitch points that bypassed the timing randomisation and containment model.
I don't see much motivation for fixing that when I can purchase a nrf52xx Bluetooth Beacon on aliexpress for €4 and flash it with firmware that pretends to be 50 different airtags, rotating every 10 minutes, and therefore bypassing all tracker detections.
It's pretty trivial to just open it up and disconnect the speaker too. I took one apart to make a custom wallet card out of it and broke the speaker in doing so; the rest of it worked perfectly fine (though obviously the warning would still work).
The xbox does have defences against this, the talk explicitly mentions rail monitoring defences intended to detect that kind of attack. It had a lot of them, and he had to build around them. The exploit succeeds because he found two glitch points that bypassed the timing randomisation and containment model.