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Security Researchers Can Turn Headphones Into Microphones (techcrunch.com)
As if we don't already have enough devices that can listen in on our conversations, security researchers at Israel's Ben Gurion University have created malware that will turn your headphones into microphones that can slyly record your conversations. TechCrunch reports: The proof-of-concept, called "Speake(a)r," first turned headphones connected to a PC into microphones and then tested the quality of sound recorded by a microphone vs. headphones on a target PC. In short, the headphones were nearly as good as an unpowered microphone at picking up audio in a room. It essentially "retasks" the RealTek audio codec chip output found in many desktop computers into an input channel. This means you can plug your headphones into a seemingly output-only jack and hackers can still listen in. This isn't a driver fix, either. The embedded chip does not allow users to properly prevent this hack which means your earbuds or nice cans could start picking up conversations instantly. In fact, even if you disable your microphone, a computer with a RealTek chip could still be hacked and exploited without your knowledge. The sound quality, as shown by this chart, is pretty much the same for a dedicated microphone and headphones. The researchers have published a video on YouTube demonstrating how this malware works.
is a microphone. Both headphones and microphone share the same mechanism (using a voice coil). The microphone is more sensitive (as it generates small alternative current when the sound makes the diaphragm vibrate) ; and headphones do the opposite, its diaphragm vibrates when the device injects positive or negative current. Even a bigger speaker is sensitive enough to act as a microphone.
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> It should be apparent if you think about it for a moment. A speaker is a transducer
Electromechanically, it's apparent. In terms of feedback that can be read by any sensory circuitry on the PC itself, it is not. A headphone or speaker circuit need have no _sensors_ that can be read or recorded by the signal generator. I'm afraid it's the introduction of simple chip solutions, designed to connect different electrical jacks to different programmable signals, and the introduction of A/D circuitry for noise cancellation and microphones that allows the cross connection of what is normally an output circuit to an input circuit.
Such features help reduce costs of circuitry for computer motherboards by providing single well designed, well understood chips for both functions. But it's not a design requirement.