Which level(s) of security as defined by the National Computer Security Center (NCSC) is attained by many “out of the box” implementations of commercially available operating systems?

A.
Level B2

B.
Level D

C.
Level D through B2

D.
Level B through B2

Explanation:
Most products are rated at between D (minimal security) to B2. Windows NT has obtained a C2 rating, which is in-between. Below is a summary of the various Security Levels, for a complete reference see:
http://www.radium.ncsc.mil/tpep/library/rainbow/5200.28-STD.html – HDR1
D: MINIMAL PROTECTION – This division contains only one class. It is reserved for those systems that have been evaluated but that fail to meet the requirements for a higher evaluation class.
C: DISCRETIONARY PROTECTION
Classes in this division provide for discretionary (need-to-know) protection and, through the inclusion of audit capabilities, for accountability of subjects and the actions they initiate.
C1: DISCRETIONARY SECURITY PROTECTION
The Trusted Computing Base (TCB) of a class (C1) system nominally satisfies the discretionary security requirements by providing separation of users and data. It 1D0-470
incorporates some form of credible controls capable of enforcing access limitations on an individual basis, i.e., ostensibly suitable for allowing users to be able to protect project or private information and to keep other users from accidentally reading or destroying their data. The class (C1) environment is expected to be one of cooperating users processing data at the same level(s) of sensitivity.
C2: CONTROLLED ACCESS PROTECTION
Systems in this class enforce a more finely grained discretionary access control than (C1) systems, making users individually accountable for their actions through login procedures, auditing of security-relevant events, and resource isolation.
B: MANDATORY PROTECTION
The notion of a TCB that preserves the integrity of sensitivity labels and uses them to enforce a set of mandatory access control rules is a major requirement in this division. Systems in this division must carry the sensitivity labels with major data structures in the system. The system developer also provides the security policy model on which the TCB is based and furnishes a specification of the TCB. Evidence must be provided to demonstrate that the reference monitor concept has been implemented.
B1: LABELED SECURITY PROTECTION
Class (B1) systems require all the features required for class (C2). In addition, an informal statement of the security policy model, data labelling, and mandatory access control over named subjects and objects must be present. The capability must exist for accurately labelling exported information. Any flaws identified by testing must be removed.
B2: STRUCTURED PROTECTION
In class (B2) systems, the TCB is based on a clearly defined and documented formal security policy model that requires the discretionary and mandatory access control enforcement found in class (B1) systems be extended to all subjects and objects in the ADP system. In addition, covert channels are addressed. The TCB must be carefully structured into protection-critical and non-protection-critical elements. The TCB interface is well defined and the TCB design and implementation enable it to be subjected to more thorough testing and more complete review. Authentication mechanisms are strengthened, trusted facility management is provided in the form of support for system administrator and operator functions, and stringent configuration management controls are imposed. The system is relatively resistant to penetration.
B3: SECURITY DOMAINS
The class (B3) TCB must satisfy the reference monitor requirements that it mediate all accesses of subjects to objects, be tamperproof, and be small enough to be subjected to analysis and tests. To this end, the TCB is structured to exclude code not essential to security policy enforcement, with significant system engineering during TCB design and implementation directed toward minimizing its complexity. A security administrator is supported, audit mechanisms are expanded to signal security- relevant events, and system recovery procedures are required. The system is highly resistant to penetration.
A: VERIFIED PROTECTIONThis division is characterized by the use of formal security verification methods to assure that the mandatory and discretionary security controls employed in the system can effectively protect classified or other sensitive information stored or processed by the system. Extensive documentation is required to demonstrate that the TCB meets the security requirements in all aspects of design, 1D0-470
development and implementation.
A1: VERIFIED DESIGN
Systems in class (A1) are functionally equivalent to those in class (B3) in that no additional architectural features or policy requirements are added. The distinguishing feature of systems in this class is the analysis derived from formal design specification and verification techniques and the resulting high degree of assurance that the TCB is correctly implemented. This assurance is developmental in nature, starting with a formal model of the security policy and a formal top-level specification (FTLS) of the design.
Incorrect Answers:
A: The B2 is a high rating, and many systems don’t achieve being classified as B2.
B: The D rating, which is minimal security, does not represent most systems, since many out of the box operating systems at least have some security or better.
D: The B to B2 rating is pretty high, and many systems don’t achieve a system that tight.