Biblio

The increasing diffusion of malware endowed with steganographic techniques requires to carefully identify and evaluate a new set of threats. The creation of a covert channel to hide a communication within network traffic is one of the most relevant, as it can be used to exfiltrate information or orchestrate attacks. Even if network steganography is becoming a well-studied topic, only few works focus on IPv6 and consider real network scenarios. Therefore, this paper investigates IPv6 covert channels deployed in the wild. Also, it presents a performance evaluation of six different data hiding techniques for IPv6 including their ability to bypass some intrusion detection systems. Lastly, ideas to detect IPv6 covert channels are presented.

New viewpoints of covert channels are presented in this work. First, the origin of covert channels is traced back to acc ess control and a new class of covert channel, air-gap covert channels, is presented. Second, we study the design of covert channels and provide novel insights that differentiate the research area of undetectable communication from that of covert channels. Third, we argue that secure systems can be characterized as fixed-source systems or continuous-source systems, i.e., systems whose security is compromised if their design allows a covert channel to communicate a small, fixed amount of information or communicate information at a sufficiently high, continuous rate, respectively. Consequently, we challenge the traditional method for measuring covert channels, which is based on Shannon capacity, and propose that a new measure, steganographic capacity, be used to accurately assess the risk posed by covert channels, particularly those affecting fixed-source systems. Additionally, our comprehensive review of covert channels has led us to the conclusion that important properties of covert channels have not been captured in previous taxonomies. We, therefore, present novel extensions to existing taxonomies to more accurately characterize covert channels.