Hard wired link between webcam and led indicator?

In light of stories about stories about secret monitoring over laptop webcams (such as this one or this one), I wonder about the reliability of the green LED next to the camera that indicates that it's in use.

Is there a known hard-wired link between the camera on a MacBook Pro and the indicator that is impossible to circumvent in software?

Would such a thing be possible given the hardware of the camera?

Solution 1:

I just read another article about that on Ars Technica

• Yes the LED is hardwired
• But it can still be bypassed

Only downside of this article, it was only tested on "old" (late PPC, early Intel) macs.

Solution 2:

Today I stumbled across a proper publication regarding this topic: Researches from the Johns Hopkins University recently published the paper "iSeeYou: Disabling the MacBook Webcam Indicator LED", showing that they were able to deactivate the iSight status LED on older MacBooks even without root access by replacing its firmware.

It appears they were able to do so by bypassing the standby signals sent by the USB interface; thus while the LED gets the order to "standby", the camera stays on.