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135. d. The major principle of configuration management is to provide a repeatable mechanism for effecting system modifications in a controlled environment. Achieving repeatable mechanism can automatically achieve the other three choices.

136. Which of the following refers to the Reference Monitor concept?

a. It is a system access control concept.

b. It is a system penetration concept.

c. It is a system security concept.

d. It is a system-monitoring concept.

136. a. The Reference Monitor concept is an access control concept that refers to an abstract computer mediating all accesses to objects by subjects. It is useful to any system providing multilevel secure computing facilities and controls.

137. Which of the following is a malicious code that replicates using a host program?

a. Boot sector virus

b. Worm

c. Multi-partite virus

d. Common virus

137. d. A common virus is a code that plants a version of itself in any program it can modify. It is a self-replicating code segment attached to a host executable.

The boot-sector virus works during computer booting, where the master boot sector and boot sector code are read and executed. A worm is a self-replicating program that is self-contained and does not require a host program. A multi-partite virus combines both sector and file-infector viruses.

138. Which of the following is not an example of built-in security features?

a. Authentication controls were designed during a system development process.

b. Fail-soft security features were installed.

c. Least-privilege principles were installed during the post-implementation period.

d. Fail-safe security features were implemented.

138. c. Built-in security means that security features are designed into the system during its development, not after. Any feature that is installed during post-implementation of a system is an example of built-on security, not built-in. Security and control features must be built in from a cost-benefit perspective.

139. An effective defense against new computer viruses does not include which of the following?

a. Program change controls

b. Virus scanning programs

c. Integrity checking

d. System isolation

139. b. Computer virus defenses are expensive to use, ineffective over time, and ineffective against serious attackers. Virus scanning programs are effective against viruses that have been reported and ineffective against new viruses or viruses written to attack a specific organization. Program change controls limit the introduction of unauthorized changes such as viruses. Redundancy can often be used to facilitate integrity. Integrity checking with cryptographic checksums in integrity shells is important to defend against viruses. System or equipment isolation to limit the spread of viruses is good, too.

140. Which of the following fully characterizes an information system’s security?

a. Confidentiality

b. Integrity

c. Assurance

d. Availability

140. c. System assurance is the basis for confidence that the security measures, both technical and operational, work as intended to protect the system and the data and information it processes. For example, software assurance achieves trustworthiness and predictable execution.

The three well-accepted and basic-level security objectives are confidentiality, integrity, and availability, and assurance can be considered an advanced-level security objective because the former culminates into the latter. What good is an information system that cannot provide full assurance with regards to its security?

141. Which of the following is an example of both preventive and detective control?

a. Audit trails

b. Antivirus software

c. Policies and procedures

d. Contingency plans

141. b. Antivirus software is a preventive control in that it stops a known virus from getting into a computer system. It is also a detective control because it notifies upon detecting a known virus. Audit trails are detective controls; policies and procedures are directive controls, whereas contingency plans are an example of recovery controls.

142. Which of the following statements dealing with security principles is not true when securing an application environment?

a. Information security functions should be isolated from nonsecurity functions.

b. Design for protection mechanisms should be simple and small in size.