In multi-processing systems, which one of the following lacks mandatory controls and is
NORMALLY AVOIDED for communication?

A.
Storage channels

B.
Covert channels

C.
Timing channels

D.
Object channels

Explanation:
Covert channel – A communication path that enables a process to transmit
information in a way that violates the system’s security policy. – Shon Harris All-in-one CISSP
Certification Guide pg 929