Researchers from the universities of Sweden and the United Kingdom have discovered a new technique by which the Android speaker and microphone smartphone can be used to steal the screen unlock pattern.
This technique works by forming a sonar system, using sound waves to track your finger position on your phone screen. The new technique has been called SonarSnoop.
To use this hack, a malicious app must run on the phone and sound beeps from the speaker so that the waves of the user's fingers are recorded by the microphone and thus identify the pattern. Interestingly, the sound waves emitted by the application are of the order of 18 kHz and 20 kHz, which are not heard by human ears.
Academics from Lancaster University in the UK and Linkoping University of Sweden have published a research paper detailing the testing of this technique in Samsung Galaxy S4 using Android 5.0.1. You can read here the research paper.
With the help of SonarSnoop, researchers have been able to reduce the number of possible unlock patterns by 70%.
This new technique is at an experimental stage at present and the results are not as accurate as you would expect. This technology used behind this technique is not new. Sonar (Sound Navigation and Ranging) is commonly used on submarines to detect obstacles and other underwater objects. However, charging a smartphone lock via Sonar is a fairly new concept.