New Scientist, November 13^th 2013 - article entitled "Can Viruses Talk"

About how a respected cyber security expert found his Apple Mac was changing configuration without him doing anything. Take it as read he reduced the configuration by disconnecting from the net, switched of all mains power, ran on batteries alone with 2 computers within "earshot". He noticed the effect at that stage, but not when the microphone(s) was disabled. Speculation is that data could be transferred even ultrasonically, at a low bit rate, but computers are left on for long periods, and they beep at you.

He did scan the Macs for viruses and found none. And Apples don't get viruses do they? Do they? So much so you can install a "Defender" on Apple products - Defender/AVI - what's in a name?

So - a subtle loophole or subtle virus? Nearly ten years ago. Apple have probably plugged that gap, without telling anyone. There are precedents for that happening.