  Covert channels is a vital setup in the analysing the strength of security in
a network.Covert Channel is illegitimate channelling 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 scheme that enables to
build robust covert channel over the network.From an attacker's perspective
this will ameliorate by placing multiple 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 such event is complicated due to lack of knowledge over the different
covert schemes. To improve the knowledge of the detection engine to detect the
hybrid covert channel scenario it is required to explore all possible
clandestine mediums used in the formation of such channels. This can be
explored by different schemes available and their entropy impact on hybrid
covert channel. The environment can be composed of resources and subject under
at-tack and subject which have initiated the attack (attacker). The paper sets
itself an objective to understand the different covert schemes and the attack
scenario (modelling) and possibilities of covert mediums along with metric for
detection.
