Cautious computer users put a piece of tape over their webcam. Truly paranoid ones worry about their devices’ microphones—some even crack open their computers and phones to disable or remove those audio components so they can’t be hijacked by hackers. Now one group of Israeli researchers has taken that game of spy-versus-spy paranoia a step further, with malware that converts your headphones into makeshift microphones that can slyly record your conversations…
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…
There’s no simple software patch for the eavesdropping attack, Guri says. The property of RealTek’s audio codec chips that allows a program to switch an output channel to an input isn’t an accidental bug so much as a dangerous feature, Guri says, and one that can’t be easily fixed without redesigning and replacing the chip in future computers.
I will bet that unless you can detach your laptop’s speakers, your entire laptop is a big NSA listening device that can beam out everything going on around it in real time on demand of any government agency’s surveillance operations. How many other Internet of Things devices with speakers, from TV’s, to intercoms, to telephones, to car entertainment systems use that same chip to govern output, and could see it shifted to an input?
It is not an accident that such a capability is built into the system in a way that cannot be ameliorated. This is the machine, thinking ahead, and preparing to penetrate every inch of your life on a moment’s notice. I would love to know what engineer put this feature into the chip, and all of their contacts prior to doing so.
I will give the surveillance state credit – it is amazingly dedicated to penetrating every aspect of people’s lives.
[…] Your Computer’s Speakers Are Spying On You […]
Yes, the government is recording everything you are doing. Don’t worry, when you get picked up by the FBI, I’ll carry on your work.
Hope you will be ready soon.
The feature is “automatic jack sensing and switching” It is how your PC can have a set of jacks on the back that default to left/right on one, mic on another, line in, etc. but can, by clicking an option, suddenly become 5.1 channel outputs. Or when you insert headphones into the front jack the sound can automatically switch off on the rear and go to the phones, without the old fashioned analog switching that introduces noise. The audio chip simply detects the load on the plug change when a plug in inserted and triggers software up in the device driver and the operating system to decide what to do about it. Pretty much any pin can have any input or output routed to/from it.
The speakers into mic trick is a very old one, I have done that one myself. Much like a basic motor can be used as a generator, a speaker generates a voltage when an external sound vibrates the cone and if amplified will produce a usable audio signal. Most speakers are just really bad at being a microphone.
With enough digital signal processing it would even, in theory, be possible to obtain an audio signal from a speaker while it was playing sound by measuring the voltage and current through it, subtracting out the signal being driven into it and a model of the distortion introduced by the imperfections of the speaker. This sounds insane, but the audio systems in quality cell phones already do processing of similar complexity to allow them to drive sound pressure levels far in excess of what would be safe for a normal amplifier and speaker of that size. The sound chip has a detailed profile of the physical parameters of the speaker and adapts the sound waveform in realtime to avoid slamming the cone of the speaker against the stops, avoid melting the driving coils, etc.