Explanation: Analyzing resources of a system is one standard for locating covert channels because the basis of a covert channel is a shared resource. The following properties must hold for a storage channel to exist:
1. Both sending and receiving process must have access to the same attribute of a shared object.
2. The sending process must be able to modify the attribute of the shared object.
3. The receiving process must be able to reference that attribute of the shared object.
4. A mechanism for initiating both processes and properly sequencing their respective accesses to the shared resource must exist.
Note: Similar properties for timing channel can be listed The following answers are incorrect: All other answers were not directly related to discovery of Covert Channels.
Reference: Acerbic Publications, Acerbic Publications (Test Series) – CRC Press LLC, Page No. 225 http://www.cs.ucsb.edu/~sherwood/cs290/papers/covert-kemmerer.pdf http://www.cs.utexas.edu/~byoung/cs361/lecture16.pdf http://www.cs.utexas.edu/~byoung/cs361/lecture16.pdf