A group of scientists from Sweden and the United Kingdom developed the SonarSnoop framework, which allows to track touch on the screen of a smartphone. The technology works by the method of echolocation, using the standard equipment of the device. This is not a replacement for the usual touchscreen, but the developers wanted to point out a new possible vector of attack by their research. This is reported by Russian IT media Xakep.
The smartphone's speakers are used to generate sound at frequencies of 18 to 20 kilohertz, which a humancan not hear. Microphones catch signals reflected from a finger or stylus. The received data is processed to obtain possible patterns of motion. Most modern devices have a pair of speakers and microphones, which allows to get a fairly accurate result.
The published work demonstrates the possibility of stealing graphic keys. For the experiment, the developers of SonarSnoop chose a Samsung Galaxy S4. Theoretically there are 389,112 possible variants of the graphic key, however, practice shows that the most popular is only 12.
Ten volunteers were offered to reproduce these keys in a special application on smartphones. The researchers decided to abandon the standard Android solution for reading graphics keys. Own software should provide more control over the course of the experiment.
Only SonarSnoop was installed directy on the devices in order to collect data, processing was performed on a separate computer. With the best method of processing, it was possible to reduce the average number of possible options from 12 to 2.71. And in some cases, the program immediately gave the right version.
SonarSnoop still exists in the form of a concept demonstrating the possibility of using echolocation. The effectiveness of the technology depends heavily on the particular device model. At the same time, developers noted that background noise has virtually no effect on the result.
Security professionals are constantly looking for and regularly detect the vulnerabilities of modern digital devices. In late August, researchers published information about the vulnerability of smartphones, inherited them from modem 80-ies of the last century.