Covert Channel Forensics on the Internet: Issues, Approaches, and Experiences

Abstract

The exponential growth of the Internet (WWW in particular) has opened-up several avenues for covert channel communication. Steganographic communication is one such avenue. Hiding secret messages in digital data such as images using steganographic software tools is becoming easier. These digital images posted in public Web sites can then be downloaded at the receiver and the hidden messages may be extracted securely. To thwart covert channels on the Internet new types of search engines that can identify, detect and track these channels are necessary. Traditional search algorithms will fail to identify these channels. In this paper, we discuss various key issues involved in developing a stego (forensic) Web search engine. We also propose approaches to address some of these issues. Finally, we discuss a prototype forensic search engine that we developed called STEALTH and discuss in detail its architecture. Some experimental results are also reported.