Abstract: “Covert channels is a vital setup in the analyzing the strength of security in a network. Covert Channel is illegitimate channeling over the secured channel and establishes a malicious conversation. The trapdoor set in such channels proliferates making covert channel sophisticated to detect their presence in network firewall. This is due to the intricate covert schemes that enable to build robust covert channel over the network. From an attacker's perspective this will ameliorate by placingmultiple such trapdoors in different protocols in the rudimentary protocol stack. This leads to a unique scenario of “Hybrid Covert Channel", where different covert channel trapdoors exist at the same instance of time in same layer of protocol stack. For detection agents to detect suchevent is complicated due to lack of knowledge over the different covert schemes. Exploring all the clandestine schemes used in formation of Hybrid Covert Channel would assist in understanding the complete search space of”

Keywords: Covert Channel, Subliminal Channel, Network Forensics, Kleptography, Trapdoors, Covert Schemes