Sign In

Communications of the ACM

ACM TechNews

Experimental Malware ­ses Inaudible Sound to Defeat Network Air Gaps

View as: Print Mobile App Share:
A woman strains to hear the inaudible.

Researchers have demonstrated that messages can be transmitted between and among laptops using audio signals inaudible to human ears.

Credit: George Marks

Researchers at the Fraunhofer Institute for Communication, Information Processing, and Ergonomics have tested the feasibility of creating a covert acoustical mesh network between multiple laptops to exchange data using near-ultrasonic frequencies. The experiments demonstrated that messages can be transmitted using audio signals in the low ultrasonic frequency range of about 20,000 Hz over a maximum distance of 19.7 meters at a rate of 20 bits/second.

The researchers placed laptops in direct line of sight to each other and adjusted the volume levels to make the transmission inaudible to observers. They built an acoustical mesh network of five laptops that relayed messages to each other using audio transmissions to show that an attack can jump network air gaps to extract data from computers infected with malware. In order for the system to work, every laptop needs to be in direct line of sight of at least one other laptop that acts as a node in the network.

"This message could just contain the recorded keystrokes, but it is also conceivable to include the GUWMANET/GUWAL headers in order to tunnel the protocol over TCP/IP and to extend the covert acoustical mesh network to another covert network at any place in the world," the researchers note.

From IDG News Service
View Full Article


Abstracts Copyright © 2013 Information Inc., Bethesda, Maryland, USA


No entries found

Sign In for Full Access
» Forgot Password? » Create an ACM Web Account