Which of the following is an unintended communication path that is NOT protected by the system’s normal
security mechanisms?

A.
A trusted path

B.
A protection domain

C.
A covert channel

D.
A maintenance hook

Explanation:
A covert channel is an unintended communication path within a system, therefore it is not protected by the
system’s normal security mechanisms. Covert channels are a secret way to convey information.
Covert channels are addressed from TCSEC level B2.
Incorrect Answers:
A: A trusted path is the protected channel that allows a user to access the Trusted Computing Base (TCB)
without being compromised by other processes or users. This is not what is described in the question.
B: A protection domain consists of the execution and memory space assigned to each process. This is not what
is described in the question.
C: A maintenance hook is a hardware or software mechanism that was installed to permit system maintenance
and to bypass the system’s security protections. This is not what is described in the question.

Krutz, Ronald L. and Russel Dean Vines, The CISSP Prep Guide: Mastering the Ten Domains of Computer
Security, John Wiley & Sons, New York, 2001, p. 219