This is an older story, but it has come around again recently.
Researchers at Israel’s Ben Gurion University have created a piece of proof-of-concept code they call “Speake(a)r,” designed to demonstrate how determined hackers could find a way to surreptitiously hijack a computer to record audio even when the device’s microphones have been entirely removed or disabled. The experimental malware instead repurposes the speakers in earbuds or headphones to use them as microphones, converting the vibrations in air into electromagnetic signals to clearly capture audio from across a room.
But, as it turns out, this is less of an out-and-out hack, but just simply taking advantage of a somewhat questionable ‘feature’:
But the Ben Gurion researchers took that hack a step further. Their malware uses a little-known feature of RealTek audio codec chips to silently “retask” the computer’s output channel as an input channel, allowing the malware to record audio even when the headphones remain connected into an output-only jack and don’t even have a microphone channel on their plug. The researchers say the RealTek chips are so common that the attack works on practically any desktop computer, whether it runs Windows or MacOS, and most laptops, too. RealTek didn’t immediately respond to WIRED’s request for comment on the Ben Gurion researchers’ work. “This is the real vulnerability,” says Guri. “It’s what makes almost every computer today vulnerable to this type of attack.”