A Completely Covert Audio Channel in Android

Abstract

A Completely Covert Audio Channel in Android by Sukanya Thakur Exfilteration of private data is a potential security threat against mobile devices. Previous research concerning such threats has generally focused on techniques that are only valid over short distances (NFC, Bluetooth, electromagnetic emanations, and so on). In this research, we develop and analyze an exfilteration attack that has no distance limitation. Specifically, we take advantage of vulnerabilities in Android that enable us to covertly record and exfilterate a voice call. This paper presents a successful implementation of our attack, which records a call (both uplink and downlink voice streams), and inaudibly transmits the recorded voice over a subsequent inaudible call, without any visual or audio indication given to the victim. We provide a detailed analysis of our attack, and we suggest possible counter measures to thwart similar attacks. ACKNOWLEDGMENTS Prof. Mark Stamp, my project guide, has supported me and kept me motivated during multiple hiccups and uncertainties I had been through in this project. He provided me with much needed guidance and information, while showing confidence in me especially at times when, in fact, I myself was uncertain on the outcome of my research and experimentation. I truly appreciate his patience and his encouragements all through this difficult path. His you-can-do-it encouragement and much needed timely tips have helped me develop independent thinking and climb the hill with confidence. Prof. Robert Chun has inculcated in me the urge to develop conceptual clarity through his term paper assignments in his classes that I took during my graduate years in San Jose State. His presentation of key ideas in the most simple possible ways has always helped me see the points through the jargon loaded confusing cluster of literature on a subject. I am thankful to him for accepting to become my committee member. Nikki Benecke Brandt's work on NFC fuzzing in Android has been the source of inspiration to me in deciding to go for this Android based project. She has always made herself available whenever I needed her inputs and help, even when it was a stretch for her during her busy schedule. I am gratified to have her as my committee member. Finally I like to thank Apala, my daughter, for remaining awake with me in the nights, always ready to serve me coffee or tea, and for assisting me by making endless adversary calls during the experimentation. v