Researchers Turn a Speaker into a Microphone

Headphones are for outputting (or hearing) sound while microphones are for delivering it across, right?

But what if I told you there was a way to use a headphone as a microphone? Turns out, there is a way and security researchers have proved it.

A few security researchers at Israel’s Ben-Gurion University decided to turn speakers into microphones for fun (and profit).

What they did is that they tweaked the RealTek audio codec chip output that is found in many desktop computers, transforming it into an output channel.

They have now presented a proof-of-concept of their software called “SPEAK(a)R”. It can be used to acquire “intelligibile audio” from earphones and then transmitted distances up to several meters away.

The result? Hackers can listen in to your conversation using your headphone, even if you have plugged them in an output-only (seemingly) jack. They also compared the quality of the sound recorded by a microphone and the sound recorded by a headphone-turned-microphone. Turns out, both of them were quite similar.

“Modern PC and laptops motherboards include integrated audio codecs hardware which allow for modification of the audio jacks’ functionality from output to input within software,” said Guri, one of the researchers.

“In this paper we examine this issue in the context of cyber-security. We present SPEAKE(a)R, a software that can render a PC, even once without microphones, into an eavesdropping device.”

The even more terrifying thing is that there is no way you can prevent this from happening. There is no driver fix or a simple software upgrade. Disabling the microphone on your computer is of no use either as any computer with a RealTek audio chip can still be hacked.

This year, Mark Zuckerberg was caught using a tape to cover the webcam on his MacBook Pro. Will we see him covering his speaker and headphones too in the next picture he uploads?

Source— TechCrunch


  • Microphone and speaker are technically same with different structure. You can always use speaker as mic by inserting jack in microphone slot in older PCs or tape recorders. I my self has been using headphones to record audio although poor quality around 22 years back as mic was very costly at that time. Since now we use digital or more correctly smart sound cards which can detect the connected device and can be controlled via software…. making it hackable.

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