- (Topic 2)
A Security Kernel is defined as a strict implementation of a reference monitor mechanism responsible for enforcing a security policy. To be secure, the kernel must meet three basic conditions, what are they?
Correct Answer:
D
A security kernel is responsible for enforcing a security policy. It is a strict implementation of a reference monitor mechanism. The architecture of a kernel operating system is typically layered, and the kernel should be at the lowest and most primitive level.
It is a small portion of the operating system through which all references to information and all changes to authorizations must pass. In theory, the kernel implements access control and information flow control between implemented objects according to the security policy.
To be secure, the kernel must meet three basic conditions: completeness (all accesses to information must go through the kernel),
isolation (the kernel itself must be protected from any type of unauthorized access),
and verifiability (the kernel must be proven to meet design specifications).
The reference monitor, as noted previously, is an abstraction, but there may be a reference validator, which usually runs inside the security kernel and is responsible for performing security access checks on objects, manipulating privileges, and generating any resulting security audit messages.
A term associated with security kernels and the reference monitor is the trusted computing base (TCB). The TCB is the portion of a computer system that contains all elements of the system responsible for supporting the security policy and the isolation of objects. The security capabilities of products for use in the TCB can be verified through various evaluation criteria, such as the earlier Trusted Computer System Evaluation Criteria (TCSEC) and the current Common Criteria standard.
Many of these security terms—reference monitor, security kernel, TCB—are defined loosely by vendors for purposes of marketing literature. Thus, it is necessary for security professionals to read the small print and between the lines to fully understand what the vendor is offering in regard to security features.
TIP FOR THE EXAM:
The terms Security Kernel and Reference monitor are synonymous but at different levels. As it was explained by Diego:
While the Reference monitor is the concept, the Security kernel is the implementation of such concept (via hardware, software and firmware means).
The two terms are the same thing, but on different levels: one is conceptual, one is "technical"
The following are incorrect answers: Confidentiality, Integrity, and Availability Policy, mechanism, and assurance Isolation, layering, and abstraction
Reference(s) used for this question:
Hernandez CISSP, Steven (2012-12-21). Official (ISC)2 Guide to the CISSP CBK, Third Edition ((ISC)2 Press) (Kindle Locations 13858-13875). Auerbach Publications. Kindle Edition.
- (Topic 6)
Which of the following devices enables more than one signal to be sent out simultaneously over one physical circuit?
Correct Answer:
B
Multiplexers are devices that enable enables more than one signal to be sent out simultaneously over one physical circuit.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 3: Telecommunications and Network Security (page 118).
- (Topic 1)
Why should batch files and scripts be stored in a protected area?
Correct Answer:
C
Because scripts contain credentials, they must be stored in a protected area and the transmission of the scripts must be dealt with carefully. Operators might need access to batch files and scripts. The least privilege concept requires that each subject in a system be granted the most restrictive set of privileges needed for the performance of authorized tasks. The need-to-know principle requires a user having necessity for access to, knowledge of, or possession of specific information required to perform official tasks or services.
Source: WALLHOFF, John, CISSP Summary 2002, April 2002, CBK#1 Access Control System & Methodology (page 3)
- (Topic 4)
Which of the following is the most important consideration in locating an alternate computing facility during the development of a disaster recovery plan?
Correct Answer:
A
You do not want the alternate or recovery site located in close proximity to the original site because the same event that create the situation in the first place might very well impact that site also.
From NIST: "The fixed site should be in a geographic area that is unlikely to be negatively affected by the same disaster event (e.g., weather-related impacts or power grid failure) as the organization’s primary site.
The following answers are incorrect:
It is close enough to become operational quickly. Is incorrect because it is not the best answer. You'd want the alternate site to be close but if it is too close the same event could impact that site as well.
It is close enough to serve its users. Is incorrect because it is not the best answer. You'd want the alternate site to be close to users if applicable, but if it is too close the same event could impact that site as well
It is convenient to airports and hotels. Is incorrect because it is not the best answer, it is more important that the same event does not impact the alternate site then convenience.
References:
OIG CBK Business Continuity and Disaster Recovery Planning (pages 368 - 369) NIST document 800-34 pg 21
- (Topic 4)
Which common backup method is the fastest on a daily basis?
Correct Answer:
B
The incremental backup method only copies files that have been recently changed or added. Only files with their archive bit set are backed up. This method is fast and uses less tape space but has some inherent vulnerabilities, one being that all incremental backups need to be available and restored from the date of the last full backup to the desired date should a restore be needed.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 3: Telecommunications and Network Security (page 69).
