Hackers could be able to tell what you are typing on your computer just by listening to your keystrokes through your smartphone’s microphone, a new study warns.
Researchers recreated a real-life office situation, complete with background chatter and the din of key clacking.
They found it was possible to tell exactly what keys were pressed on a keyboard with up to 41 per cent accuracy – and believe this figure could rise with refinement.
The method could be used to crack even the strongest password or steal credit card information, they caution.
Researchers at Southern Methodist University (SMU) set up a realistic boardroom scenario.
They asked subjects to make notes of what was discussed on their laptops and used an app to listen in on their typing.
These audio signals were processed by their software to recreate the words written by their test subjects.
Experts were able to correctly identify 41 out of 100 words typed using the microphones from eight handsets placed on tables in the room.
They also knew if the typist was back-spacing or making corrections and believe they can refine their method further.
Their trick for bugging any keyboard is using existing smartphone sensors, which are automatically always on, detecting vibrations and then deciphering the sounds later.
Professor Mitch Thornton said: ‘We wanted to understand if what you’re typing on your laptop, or any keyboard for that matter, could be sensed by just those mobile phones that are sitting on the same table.
‘The answer was a definite, ‘Yes.’ There’s no way to know if you’re being hacked this way.’
Experts said the covert spying technique isn’t perfect and could be foiled – with a simple tablecloth.
Study co-author Dr Eric Larson said: ‘A hacker would need to know the material type of the table because different tables create different sound waves when you type.
‘For instance, a wooden table like the kind used in this study sounds different than someone typing on a metal tabletop.
‘An attacker would also need a way of knowing there are multiple phones on the table and how to sample from them.’
The research team hope their findings will prompt manufacturers to step-up security on their phones.
Dr Larson added: ‘Based on what we found, I think smartphone makers are going to have to go back to the drawing board and make sure they are enhancing the privacy with which people have access to these sensors in a smartphone.’
The full findings of the study were published in the journal Interactive, Mobile, Wearable and Ubiquitous Technologies.