CS 6238 Midterm Exam Questions with
Verified Answers & Rationales | Secure
Computer Systems Study Guide | Latest 2026
Edition
,1. Which property of a trusted computing base means it cannot be
modified by untrusted code?
A. Complete mediation
B. Correctness
C. Tamper-proofness
D. Open design
C. Tamper-proofness Rationale: The TCB must resist modification
by untrusted subjects.
2. Which property of a trusted computing base means every access
must be checked?
A. Tamper-proofness
B. Complete mediation
C. Economy of mechanism
D. Least common mechanism
B. Complete mediation Rationale: Complete mediation requires
that every access be validated against policy.
3. Which property of a trusted computing base means it contains no
exploitable flaws?
A. Correctness
B. Isolation
C. Least privilege
, D. Open design
A. Correctness Rationale: Correctness means the TCB behaves as
intended and has no vulnerabilities.
4. The reference monitor is best described as:
A. A hardware cache controller
B. An abstract enforcement mechanism for access control policy
C. A password database
D. A network firewall only
B. An abstract enforcement mechanism for access control policy
Rationale: The reference monitor mediates all subject-object
accesses according to policy.
5. Which requirement is not traditionally required of a reference
monitor?
A. Complete mediation
B. Tamper-proofness
C. Verifiability
D. User-friendliness
D. User-friendliness Rationale: Reference monitor requirements
focus on enforcement, protection, and verification, not usability.
6. The principle of least privilege states that:
A. All users should have administrator rights
, B. Subjects should receive only the privileges needed for their task
C. Mechanisms should be complex
D. Policies should be secret
B. Subjects should receive only the privileges needed for their
task Rationale: Least privilege limits authority to reduce damage
from faults or attacks.
7. Economy of mechanism recommends that security designs should
be:
A. As complex as possible
B. Small and simple
C. Hidden from users
D. Based only on passwords
B. Small and simple Rationale: Simpler mechanisms are easier to
verify and less likely to contain flaws.
8. Open design means:
A. The security policy must be public to attackers
B. Security should not depend on secrecy of the design
C. All source code must be public
D. Passwords must be public
B. Security should not depend on secrecy of the design Rationale:
Verified Answers & Rationales | Secure
Computer Systems Study Guide | Latest 2026
Edition
,1. Which property of a trusted computing base means it cannot be
modified by untrusted code?
A. Complete mediation
B. Correctness
C. Tamper-proofness
D. Open design
C. Tamper-proofness Rationale: The TCB must resist modification
by untrusted subjects.
2. Which property of a trusted computing base means every access
must be checked?
A. Tamper-proofness
B. Complete mediation
C. Economy of mechanism
D. Least common mechanism
B. Complete mediation Rationale: Complete mediation requires
that every access be validated against policy.
3. Which property of a trusted computing base means it contains no
exploitable flaws?
A. Correctness
B. Isolation
C. Least privilege
, D. Open design
A. Correctness Rationale: Correctness means the TCB behaves as
intended and has no vulnerabilities.
4. The reference monitor is best described as:
A. A hardware cache controller
B. An abstract enforcement mechanism for access control policy
C. A password database
D. A network firewall only
B. An abstract enforcement mechanism for access control policy
Rationale: The reference monitor mediates all subject-object
accesses according to policy.
5. Which requirement is not traditionally required of a reference
monitor?
A. Complete mediation
B. Tamper-proofness
C. Verifiability
D. User-friendliness
D. User-friendliness Rationale: Reference monitor requirements
focus on enforcement, protection, and verification, not usability.
6. The principle of least privilege states that:
A. All users should have administrator rights
, B. Subjects should receive only the privileges needed for their task
C. Mechanisms should be complex
D. Policies should be secret
B. Subjects should receive only the privileges needed for their
task Rationale: Least privilege limits authority to reduce damage
from faults or attacks.
7. Economy of mechanism recommends that security designs should
be:
A. As complex as possible
B. Small and simple
C. Hidden from users
D. Based only on passwords
B. Small and simple Rationale: Simpler mechanisms are easier to
verify and less likely to contain flaws.
8. Open design means:
A. The security policy must be public to attackers
B. Security should not depend on secrecy of the design
C. All source code must be public
D. Passwords must be public
B. Security should not depend on secrecy of the design Rationale:
