Can mobile malware be activated via sensors available on current mobile devices, and receive commands through out-of-band communication methods? If you ask a group of researchers from the University of Alabama at Birmingham and the Polytechnic Institute of NYU, the answer is yes.
To prove their theory, they have created and tested proof-of-concept Android apps that received command and control trigger messages from a distance of 55 feet indoors and 45 feet outdoors, sent by using only low-end PC speakers with minimal amplification and low-volume.
In theory, such a signal can be incorporated into TV or radio programs, background music services, Internet TV program and even musical greeting cards, and the signal is received even if the device is located in a user’s pocket.
When it comes to light signals, they discovered that they work best when it’s dark out, or if the device is in a poorly lit environment, and that magnetic signals have the shortest range because they are quickly dispersed as they travel through the air. Nevertheless, the researchers say that magnetic signal transmitters can easily be incorporated into places where users are bound to be come in range (tight passages such as doorways or door frames, and very crowded areas).
This type of malware would obviously be used for very localized attacks, and the researchers have described many possible ones in their white paper, including DDoS attacks, safety hazards, distraction attacks, and more.
They also provided insight into possible defense mechanisms for these attacks: intrusion detection applications on the devices that would disrupt the signaling, detection of malicious applications by checking the level of power consumed by applications that access sensors, and finally by monitoring external media streams for malicious communication.