Which definition below best describes a covert channel?

A.
A server program using a port that is not well known

B.
It is one of the weak channels used by WEP that makes it insecure

C.
Making use of a protocol in a way it was not intended to be used

D.
It is the multiplexing taking place on a communication link

Explanation:
A covert channel is a hidden communication channel not intended for information transfer at all. Redundancy can often be used to communicate in a covert way. There are several ways that hidden communication can be set up.