They have a point though. Why would there be any software that controls the LED? Is it not more secure to have it hooked up directly to the camera power line and turn them both on and off inseparably?

Turning off the camera power would mean it wouldn't show up on the bus, so the computer wouldn't know it existed.

It would make sense for the camera itself to drive the LED, instead of the computer/drivers doing it. I don't know if the camera ICs support this or not, though -- if not, it's not really something Apple can add if they're integrating a standard camera component. On the other hand, they control the T1 entirely, so they can easily do this with the new architecture.

From what I recall when it was in the news, the camera does control the LED, but it's just a USB camera on the USB bus, so the demo attack worked by reflashing the software on the camera.

I write a piece of malware that pops the camera on long enough to snap a single frame and then turn back off. The LED blinks, quite possibly too fast for you to notice.

OTOH, you can delay the LED and have it very noticeably on for a second or two when it's software-controlled.

How 'bout some pulse shaping. Rising edge of the camera power triggers a latch, whose output is pulse-shaped so that you get a little attention-catching "LED flash" when the camera turns on (brightness tapers off quickly) and is just dimly / visibly lit beyond that. This could be done with 1970s hardware with maybe two chips and some passives. Maybe one chip if you're getting ingenious.

An attacker could piggyback on user initiated sessions of video camera use. After the user closes the connection, it could immediately trigger an extra 0.1s session that would go unnoticed because of the proximity with the user intended session.

Good point, but then why not implement the delay in immutable (and trivial and cheap) hardware? Is this not both simpler and more secure?

I guess, yeah, you could do it in hardware. But I don't think, then, it ends up being directly connected to the power feed for the camera itself, yeah? You start creating false-status cases. (This is speculation; I am not an electronics wizard.)

One word: capacitor. Seriously, solved case for many many decades

Power->delay off circuit->LED. Seems pretty direct to me. The delay off circuit would probably have its own connection to power as well.

Post 2013? that's exactly how it was hooked up.