Shulou(Shulou.com)11/24 Report--

CTOnews.com, March 15 (Xinhua)-- experts from Koryo University's School of Cyber Security recently discovered a very covert means of information theft, using microphones built into smartphones or laptops to monitor the internal speakers of the device to steal data within 5 feet.

Experts call the attack "Casper" and require a laptop running Ubuntu 20.04 and a Samsung Galaxy Z Flip 3 phone running Android. CTOnews.com learned from the report that experts use the built-in tape recorder function of the phone and use the highest sampling frequency of 20kHz to record Morse code from the target machine.

The researchers set the bit length to 100ms and used a combination of 18kHz and 19kHz frequencies to simulate dots and dashes, respectively. The phone is 1.6ft from the target computer and can successfully steal the word "convert" sent from the target device.

The researchers also conducted another successful test involving binary data, sending 1s and zeros to Samsung smartphones using a bit length of 50 milliseconds and a combination of 18kHz and 19kHz frequencies.

Based on these two tests, the researchers realized that bit length would affect the error rate of transmission and found that a bit length of 50 milliseconds was five times more likely to make an error than a bit length of 100 milliseconds at a distance of 200 centimeters.

The error rate becomes worse at 30 milliseconds to 10 milliseconds, about 40-50% compared with the sampling frequency of 50 milliseconds.

This attack strategy is specifically designed to attack critical system infrastructure isolated from any computer network. The attacker needs to gain physical access to the target machine and install a virus that can locate sensitive data and send it to the attacker through high-frequency audio waves.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.