CISSP Practice полностью

The principle of process isolation or separation is employed to preserve the object’s wholeness and subject’s adherence to a code of behavior. It is necessary to prevent objects from colliding or interfering with one another and to prevent actions of active agents (subjects) from interfering or colluding with one another.

The principle of hardware segmentation provides hardware transparency when hardware is designed in a modular fashion and yet interconnected. A failure in one module should not affect the operation of other modules. Similarly, a module attacked by an intruder should not compromise the entire system. System architecture should be arranged so that vulnerable networks or network segments can be quickly isolated or taken offline in the event of an attack. Examples of hardware that need to be segmented include network switches, physical circuits, and power supply equipment.

The abstraction principle is related to stepwise refinement and modularity of programs. As the software design evolves, each level of module in a program structure represents a refinement in the level of software abstraction. Abstraction is presented in levels, where a problem is defined and a solution is stated in broad terms at the highest level of abstraction (during requirements and analysis phases) and where source code is generated at the lowest levels of abstraction (during programming phase).

The accountability principle holds an individual responsible for his actions. From this principle, requirements are derived to uniquely identity and authenticate the individual, to authorize his actions within the system, to establish a historical track record or account of these actions and their effects, and to monitor or audit this historical account for deviations from the specified code of action.

The security kernel principle is the central part of a computer system (software and hardware) that implements the fundamental security procedures for controlling access to system resources. The principle of a reference monitor is the primary abstraction enabling an orderly evaluation of a standalone computer system with respect to its abilities to enforce both mandatory and discretionary access controls.

The principle of complete mediation stresses that every access request to every object must be checked for authority. This requirement forces a global perspective for access control, during all functional phases (for example, normal operation and maintenance). Also stressed are reliable identification access request sources and reliable maintenance of changes in authority. The principle of open design stresses that design secrecy or the reliance on the user ignorance is not a sound basis for secure systems. Open design enables open debate and inspection of the strengths, or origins of a lack of strength, of that particular design. Secrecy can be implemented through the use of passwords and cryptographic keys, instead of secrecy in design.

119. Which of the following is a reactive countermeasure in defending against worms?

a. Packet filtering firewalls

b. Stackguarding

c. Virus scanning tool

d. Virtual machine

119. c. Virus scanners, being one of reactive (detective) countermeasures, search for “signature strings” or use algorithmic detection methods to identify known viruses. These reactive methods have no hope of preventing fast spreading worms or worms that use zero-day exploits to carry out their attacks.

The other three choices are examples of proactive (preventive) countermeasures. Packet-filtering firewalls block all incoming traffic except what is needed for the functioning of the network. Stackguarding prevents worms from gaining increased privileges on a system. A virtual machine prevents potentially malicious software from using the operating system for illicit actions.

120. Which of the following is better for training IT staff in malware incident handling?

a. Use an isolated test system.

b. Use an infected production system.

c. Keep the test system and the production system physically separate.

d. Keep the test system and the production system logically separate.

120. a. Malware test systems and environments are helpful not only for analyzing current malware threats without the risk of inadvertently causing additional damage to the organization, but also for training staff in malware incident handling. An infected production system or a disk image of an infected production system could also be placed into an isolated test environment. Physical separation may not be possible at all times; although, logical separation might be possible. Both physical and logical separation are important but not as important as using an isolated test system.