CCHEF – Covert Channels Evaluation Framework Design and Implementation

Communication is not necessarily made secure by the use of encryption alone. The mere existence of communication is often enough to raise suspicion and trigger investigative actions. Covert channels aim to hide the very existence of the communication. The huge amount of data and vast number of different protocols in the Internet makes it ideal as a high-bandwidth vehicle for covert communications. Covert channels are hidden inside pre-existing overt communication by encoding additional semantics onto ‘normal’ behaviours of the overt channels. We have developed CCHEF – a flexible and extensible software framework for evaluating covert channels in network protocols. The framework is able to establish covert channels across real networks using real overt traffic, but can also emulate covert channels based on overt traffic previously collected in trace files. In this paper we present the design and implementation of CCHEF.