Volume 2/4
Library No S-239,689
Version 1
Information contained within the Procurement Guideline Series will facilitate subsequent development of procurement guidance for the "Federal Criteria." This series also includes information being developed for certification and accreditation guidance.
The business of computers, security, and acquisitions is complex and dynamic. As the Director, National Computer Security Center, I invite your recommendations for revision to this technical guideline. Our staff will work to keep this guideline current. However, experience of users in the field is the most important source of timely information. Please send comments and suggestions to:
National Security Agency
9800 Savage Road
Fort George G. Meade, MD 20755-6000
ATTN: Standards, Criteria, and Guidelines Division
30 June 1993
Patrick R. Gallagher, Jr.
Director
National Computer Security Center
LIST OF FIGURES
Figure 2-1 Security Related Areas 5
LIST OF TABLES
Table 1 Procurement Guideline Series 1
Table 2 RFP Organization 7
Table 3 Data Deliverables 37
Table 1: Procurement Guideline Series
------------------------------------------------------------------------------
------------
An Introduction to Procurement Initiators on Computer Security
Requirements, December
1992.
Language for RFP Specifications and Statements of Work---An Aid to
Procurement Initiators
(this guideline).
Computer Security Contract Data Requirements List and Data Item Descriptions
Tutorial (to be published in 1993).
How to Evaluate a Bidder's Proposal Document---An Aid to Procurement
Initiators
and Contractors (to be published in 1993).
------------------------------------------------------------------------------
------------
DoD Directive 5200.28, Security Requirements for Automated Information
Systems (AISs), provides security requirements concerning all protection aspects
of automated information systems. It specifies DoD 5200.28-STD, DoD Trusted
Computer System Evaluation Criteria (TCSEC), as the requirement source for
trusted computer systems. The second page of DoD 5200.28-STD states: "This
document is used to provide a basis for specifying security requirements in
acquisition specifications."
The purpose of this document is to facilitate the contracting process, provide uniformity in competitive acquisitions, minimize procurement cost and risk, avoid delays in the solicitation process, and help ensure the solicitation is complete before its issuance.
DoD agencies should use this document whenever considering the acquisition of trusted computer systems. System security requirements are provided in contract language for direct incorporation into an RFP. The language duplicates the words and intent of the TCSEC.
a. Public Law 98-369, "Competition in Contracting Act of 1984."
b. Title 41, United States Code, Section 418, "Advocates for Competition."
c. Title 10, United States Code, Section 2318, "Advocates for Competition."
d. DoD Instruction 5000.2, Defense Acquisition Management Policy, February 23, 1991, pp. 5-A-2 through 4.
e. DoD 5000.2-M, Defense Acquisition Management Documentation and Reports, February, 1991, p. 4-D-1-3 d.(1).
For solutions that use EPL products, not only have the specifications of the evaluated Division/Class been satisfied, but the assurance tasks have been completed and the required documentation produced. Certification evidence, analyses, and operational documents previously produced for an NSA evaluation may be available to ensure trustworthiness and used directly for certification and satisfaction of required proposal and contract data. The results are less development risk and a lower overall cost to the bidder and, consequently, to the Government.
For a defined entity of a system to be regarded as secure in the TCSEC sense means that, at a minimum, all of the requirements of some specified TCSEC Division/Class must be met. This is discussed further in Volume 1, Chapter 3. To call that entity, for example, a Class B2 entity, would require NSA evaluation as a product satisfying the Class B2 criteria. (This convention has evolved over the past several years so that products would not be misrepresented in their evaluation status.)
A successful certification evaluation of an entity (which has not been placed on the NSA EPL) can only state that evaluation and approval have been completed as part of a certification process against the Class B2 set of requirements.
The rationale for this approach is as follows:
a. Although a Division/Class of the TCSEC is used as the basis for the secure part of a system, the procurement and build process can introduce new, conflicting requirements and relax, reinterpret, or change the intent of some of the existing TCSEC requirements. Only an exact evaluation can determine this.
b. The certification evaluation process addresses the needs of a single implementation. It has generally not experienced the finely honed expertise of the NSA evaluation process and personnel and does not have the same assurance for additional applications as does an EPL product.
If there are fewer than five items on the EPL meeting the stated requirements (not just security requirements), the RFP will not dictate that an item come from the EPL. Also, the process for placement on the EPL is itself a restricted, Government controlled process. To state such a requirement in the RFP would constitute a discrimination against other vendors desiring to bid. It also cannot be stated that, for example, "a B2 system is required" because that implies the solution must be taken from the EPL. Therefore, the specific TCSEC requirements necessary to meet a certain Division/Class rating must be spelled out, without stating that the B2 product is desired. However, the desire for decreased risk and cost (common to EPL products) is normally a strong factor for source selection.
This set of four acquisition documents is not to be misunderstood as DoD policy when it comes to addressing the situation of acquiring complex systems composed of many heterogeneous components. The reason is that the DoD policy has not been finalized that addresses systems with combinations of EPL products and "built and certified" system entities, which may or may not use Division/Class criteria as requirements from DoD 5200.28- STD.
What will be required for more complicated systems will be a policy for integrating entities, to include determining interface requirements and global policies to be supported across entities. As soon as these composition policies are issued by the DoD, this guideline series will be updated to reflect policy changes. In the meantime, for Program Managers faced with the more complicated situations not currently dealt with in this series, it is hoped that the principles of these guidelines can be extrapolated, using guidance from the NCSC-TG-005, Trusted Network Interpretation (TNI) of the Trusted Computer System Evaluation Criteria (TCSEC); NCSC-TG-021, Trusted Database Management System Interpretation (TDI) of The Trusted Computer System Evaluation Criteria; and NCSC-TG-009, Computer Security Subsystem Interpretation (CSSI) of the Trusted Computer System Evaluation Criteria.
The TCSEC was published in 1983 and revised to become a DoD standard in December 1985 to provide criteria for evaluating security features and assurance requirements available in "trusted, commercially available, automatic data processing systems."
The process for acquiring trusted systems is slightly different than other acquisitions. The major differences are that 1) the security requirements may become a major constraining factor in determining the solution needed to meet the remaining requirements and 2) there exists a void of acquisition guidance for AIS security.
The challenge for the procurement initiator is to specify the requirements with sufficient clarity and flexibility to achieve the desired security functions without limiting the ingenuity and ability of the offerors to supply a compliant overall solution.
The procurement process begins with various Government personnel determining operational requirements. Personnel include, but are not limited to, mission users, Program Managers, and acquisition representatives. The primary goals during this phase include determining the Division/Class and mode of operation, as well as identifying the required security features and assurances.
Selection of these security specifications requires a clear understanding of the system users' operational and mission needs, the relevant DoD security policies, available technologies, and the system's operational environment. Procurement initiators and offerors must also consider the security--related areas listed in Figure 2-1 below. More detailed information concerning these security areas can be found in DoD 5200.1-R, DoD Directive 5200.28, and DoD 5200.28-M.
Physical Security
Communications Security
Procedural Security
Emission Security
Personnel Security
The Designated Approving Authority (DAA) is responsible under Enclosure 4 of DoD Directive 5200.28 to determine the minimum AIS computer--based security requirements for the mission profile of the system being acquired. Any adjustments to computer security evaluation Division/Class (per step 6 of enclosure 4) will have been completed prior to using this guideline. The Division/Class that results from this assessment may be changed based on other factors considered by the DAA. The final Division/Class assigned to the system will be used to isolate the appropriate section of the evaluation criteria in the TCSEC, (which is organized by Division/Class).
Later in Chapter 5 of this document, we will address specific protection topics in the TCSEC. The paragraph will be used that corresponds to the Division/Class being supported in this procurement. Chapter 5 will identify both Division/Class and the corresponding TCSEC paragraph number to assist the procurement initiator in construction of the RFP.
Working with acquisition personnel, the procurement initiators should consult this guideline using the Division/Class selected for the system. The specification language contained in or referenced by this guideline can be applied directly to selected features and assurances. The statements can be amplified to meet specific operational requirements. Procurement initiators and acquisition personnel must ensure that the security specifications and work statements in Section C of the RFP allow EPL solutions, do not preclude other solutions, and are compliant with the DAA's accreditation requirements. NSA is eager to help in this determination. The requirements of the TCSEC will be carried through the development life cycle of the system: RFP, contract, test, certification, and accreditation.
Table 2: RFP Organization
Letter Section Title
A Solicitation/Contract Form,Standard Form 33
B Supplies or Services with Prices and Costs
C Descriptions/Specifications/Statement of Work
D Packaging and Marking
E Inspection and Acceptance
F Deliveries and Performance
G Contract Administration Data
H Special Contract Requirements
I Contract Clauses
J List of Documents,Exhibits and Other
Attachments
K Representations,Certifications and Other
Statements of Offerors or Quoters
L Instructions, Conditions, and Notices to
Offerors
M Evaluation Factors for Award
a. The Contract Data Requirements List (CDRL). It references specific Data Item Description (DID) requirements, which are provided in Volume 3 of the Procurement Guideline Series and also are referenced in RFP Attachment A contained in Chapter 5. Each SOW task is linked to one or more CDRLs; each CDRL identifies a document or other data that the offeror is required to deliver, along with specific information about that document (e.g. schedule, number and frequency of revisions, distribution). Associated with each CDRL is a DID that specifies the document's content and format. Where requirements differ, there are unique DIDs for each Division/Class.
b. Glossary. Even though it is presented separately, the glossary is an important part of the specifications and the Statements of Work because it precisely defines terms and further clarifies the language intent. The glossary is included as RFP Attachment B in Chapter 5 of this guideline.
c. Acronyms. Acronyms used in the RFP must be defined in their first us and must also be identified in the accompanying acronym list. Acronyms are included as RFP Attachment C in Chapter 5 of this guideline.
d. References. References have been identified for incorporation into the RFP. Terms support and are compatible with the specification language, and as such, become an integral part. The references are for technical supporting information and should not be interpreted as requirements. References are included as RFP Attachment D Chapter 5 of this guideline.
Nonmandatory requirements and solutions can also be proposed by the bidder if this is allowed by the RFP. Again bidders will not be penalized for not proposing nonmandatory requirements, for proposing unacceptable requirements, for proposing unacceptable solutions, or for proposing unacceptable desirable options or features. They can gain points by proposing acceptable solutions to acceptable requirements, whether these requirements become part of the contract or not.
Options are requirements that may be proposed by the Government, but that are not necessarily intended to be purchased at the same time as the rest of the features. The Government may still want these options addressed in the proposal and evaluated as if they were mandatory requirements.
The features and assurances for a given TCSEC Division/Class are inseparable. If requirements or taskings are eliminated from a specific level of trust, then that level cannot be certified. If requirements are added, existing EPL solutions could be eliminated.
The Trusted Computing Base (TCB) is the totality of protection mechanisms, hardware, software and/or firmware, the collection of which is responsible for enforcing security. The TCB is the trusted part, but not necessarily the total, of the offeror's solution.
Certain conventions are used in this chapter. The words in bold are either words intended for use in the RFP or references to words intended for use in the RFP. For example, bold paragraphs normally reference specific paragraphs of DoD 5200.28-STD that are suggested for use verbatim in the RFP document. Paragraphs applicable to only a Division/Class range will have that range in parentheses prior to the paragraph or group of paragraphs. Paragraphs in which the Division/Class are absent are applicable to all Divisions/Classes (C2-- A1).
Topics in Section C are divided into paragraphs as follows:
a. Text of the Specification or Statement of Work. These are words or references to words suggested for inclusion in the RFP.
b. Important References. These references should be included in the RFP. They are generally guidelines intended to explain and interpret the TCSEC for the bidder. These references will be redundantly contained in the list of references accompanying the RFP. It is important to emphasize that even though these references are bold and will be contained in the RFP, they are not RFP requirements.
c. Procurement Considerations. Here issues are discussed that have arisen in previous procurements or are apt to arise in future procurements. These issues should be considered by the procurement initiator in the context of his/her particular procurement to circumvent possible later contractual or certification problems. These considerations are not complete, but offer guidance based on known experiences. They are not in bold and therefore we do not automatically intend their inclusion in the RFP. Only if the procurement initiator decides to make them requirements will they be included in the RFP.
The standard language and form for the trusted elements of a secure system, along with important discussion, are provided in the remainder of this chapter, organized according to a subset of the sections of the RFP.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class C2, repeat TCSEC Section 2.2.1.1.
For Class B1, repeat TCSEC Section 3.1.1.1.
For Class B2, repeat TCSEC Section 3.2.1.1.
For Class B3, repeat TCSEC Section 3.3.1.1.
For Class A1, repeat TCSEC Section 4.1.1.1.
Important References
Note: References are for information only and, unless specified elsewhere, are not to be taken as requirements.
NCSC-TG-003, A Guide to Understanding Discretionary Access Control in Trusted Systems, September 30, 1987.
Discretionary Access Control Procurement Considerations
Unauthorized users include both those not authorized to use the system and legitimate users not authorized to access a specific piece of information being protected.
"Users" do not include "operators," "system programmers," "Security Officers," and other system support personnel. The latter are distinct from users and are subject to the Trusted Facility Management and the System Architecture requirements.
Deletion of subjects (e.g., users) and objects (e.g., data) is a potential problem. The mechanism should handle the deletion effectively, making certain that dangling references do not grant unintended access.
The ability to assign access permissions to an object by a user should be controlled with the same precision as the ability to access the objects themselves. Four basic models for control exist: hierarchical, concept of ownership, laissez--faire, and centralized. These are discussed in NCSC-TG- 003.
The TCB should enforce need--to--know access restrictions placed on information managed by the information system. The need--to--know access restrictions for the information, when created or changed, should be determined by the office of primary responsibility or the originator of the information. Only users determined to have appropriate clearances in addition to required "need-to-know" for information should be allowed to access the information.
The design must consider that discretionary access control is usually used for both user access control and system access control. For example, the system may contain several types of objects (known as public objects) that are designed to be read by all users, or executed by all users, but allowing only trusted subjects modification privileges.
Discretionary access control will not stop Trojan horses. An attacker can trick a more privileged user to run a program containing a Trojan horse that in turn copies the user access files to the attackers address space. Trojan horses are addressed in NCSC-TG-003.
The commercial--off--the--shelf (COTS) systems may vary with respect to the granularity of objects to which discretionary access control is applied. Generally, they are organized to provide discretionary access control (DAC) at the file level or at the application level. Database design can often handle the cases when a different level of granularity is desired by the procuring agency so that EPL products can apply. The procuring agency should take particular care, whenever possible, to write RFP specifications for DAC that can be met by at least some existing commercially available products. (This is further addressed in Volume 1, Chapter 3.)
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class C2, repeat TCSEC Section 2.2.1.2.
For Class B1, repeat TCSEC Section 3.1.1.2.
For Class B2, repeat TCSEC Section 3.2.1.2.
For Class B3, repeat TCSEC Section 3.3.1.2.
For Class A1, repeat TCSEC Section 4.1.1.2.
Important References
Note: References are for information only and, unless specified elsewhere, are not to be taken as requirements.
NCSC-TG-025, A Guide to Understanding Data Remanence in Automated Information Systems, September 1991.
NCSC-TG-018, A Guide to Understanding Object Reuse in Trusted Systems, July, 1992.
Object Reuse Procurement Considerations
The purpose of object reuse mechanisms is to prevent disclosure of sensitive information by ensuring that residual information is no longer available. This objective can be achieved by clearing objects either upon allocation or deallocatation.
Object reuse is a concern when an object is not fully allocated, that is the granularity is larger than the data. The object reuse requirement must be satisfied based on the object size, not the data allocation.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class B1, repeat TCSEC Section 3.1.1.3.
For Class B2, repeat TCSEC Section 3.2.1.3.
For Class B3, repeat TCSEC Section 3.3.1.3.
For Class A1, repeat TCSEC Section 4.1.1.3.
Important References
(None)
Labels Procurement Considerations
The tranquillity principle states that the security level of an object cannot change while the object is being processed by a system. The same can be stated about changes to security clearances. This is a critical area, both from the standpoint of changes only being invocable by an authorized individual under the direct control of the TCB and ensuring the system cannot be spoofed when such changes are being made.
Labeling of data is not used solely to control classified information. The mandatory policy can also be used for unclassified sensitive or privacy applications.
A distinction must be made between objects that are explicitly labeled and those that are implicitly labeled. For example, a labeled file may contain many tuples or records mediated by the reference monitor.
Internal TCB variables that are not visible to untrusted subjects need not be labeled, provided they are not directly or indirectly accessible by subjects external to the TCB. However, it is important to understand that such internal variables can function as covert signalling channels when untrusted subjects are able to detect changes in these variables by observing system behavior.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class B1, repeat TCSEC Section 3.1.1.3.1.
For Class B2, repeat TCSEC Section 3.2.1.3.1.
For Class B3, repeat TCSEC Section 3.3.1.3.1.
For Class A1, repeat TCSEC Section 4.1.1.3.1.
Important References
None
Label Integrity Procurement Considerations
Care is needed when specifying the means of binding an object and its label. A cryptographic mechanism is one of many approaches adequate to provide assurance of the binding since the relationship and content are preserved, and there is protection from disclosure.
The form of internal sensitivity labels may differ from their external (exported) form, but the meaning must be retained.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class B1, repeat TCSEC Section 3.1.1.3.2.
For Class B2, repeat TCSEC Section 3.2.1.3.2.
For Class B3, repeat TCSEC Section 3.3.1.3.2.
For Class A1, repeat TCSEC Section 4.1.1.3.2.
Important References
None
Exportation of Labeled Information Procurement Considerations
Changes in designation should be made by a properly authorized individual, normally the System Administrator or the Security Officer, considering the tranquillity principle. Such changes are auditable.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class B1, repeat TCSEC Section 3.1.1.3.2.1.
For Class B2, repeat TCSEC Section 3.2.1.3.2.1.
For Class B3, repeat TCSEC Section 3.3.1.3.2.1.
For Class A1, repeat TCSEC Section 4.1.1.3.2.1.
Important References
None
Exportation to Multilevel Devices Procurement Considerations
The sensitivity label of an object imported to a multilevel device must be within the range of the device and considered to be accurate by the TCB. It is considered to be accurate because it has been protected by the security mechanisms of the environment through which it has traversed before it reaches the multilevel device.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class C2, repeat TCSEC Section 2.2.1.3.2.2.
For Class B1, repeat TCSEC Section 3.1.1.3.2.2.
For Class B2, repeat TCSEC Section 3.2.1.3.2.2.
For Class B3, repeat TCSEC Section 3.3.1.3.2.2.
For Class A1, repeat TCSEC Section 4.1.1.3.2.2.
Important References
None
Exportation to Single--Level Devices Procurement Considerations
Sometimes operational use of a single level device is actually to be at one level for a period of time and then to switch to another level. Here it is wise to employ labels. If labels are not used, then tranquillity must be observed during configuration change with a positive action to ensure the level of the device is known to users and observed by the reference validation mechanism.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class B1, repeat TCSEC Section 3.1.1.3.2.3.
For Class B2, repeat TCSEC Section 3.2.1.3.2.3.
For Class B3, repeat TCSEC Section 3.3.1.3.2.3.
For Class A1, repeat TCSEC Section 4.1.1.3.2.3.
Important References
None
Labeling Human--Readable Output Procurement Considerations
The System Administrator is the "user" designated to specify the printed or displayed sensitivity label that is to be associated with exported information. The TCB is required to mark the beginning and end of all human readable, paged, hard--copy output with sensitivity labels that properly represent the sensitivity of the output. This helps users protect data they are using.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class B2, repeat TCSEC Section 3.2.1.3.3.
For Class B3, repeat TCSEC Section 3.3.1.3.3.
For Class A1, repeat TCSEC Section 4.1.1.3.3.
Important References
None
Subject Sensitivity Labels Procurement Considerations
None
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class B2, repeat TCSEC Section 3.2.1.3.4.
For Class B3, repeat TCSEC Section 3.3.1.3.4.
For Class A1, repeat TCSEC Section 4.1.1.3.4.
Important References
None
Device Labels Procurement Considerations
None
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class B2, repeat TCSEC Section 3.2.1.4.
For Class B3, repeat TCSEC Section 3.3.1.4.
For Class A1, repeat TCSEC Section 4.1.1.4.
TCSEC Section 9.0, "A Guideline on Configuring Mandatory Access Control Features."
Important References
None
Mandatory Access Control Procurement Considerations
None
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class C2, repeat TCSEC Section 2.2.2.1.
For Class B1, repeat TCSEC Section 3.1.2.1.
For Class B2, repeat TCSEC Section 3.2.2.1.
For Class B3, repeat TCSEC Section 3.3.2.1.
For Class A1, repeat TCSEC Section 4.1.2.1.
Important References
Note: References are for information only and, unless specified elsewhere, are not to be taken as requirements.
CSC-STD-002-85, Department of Defense (DoD) Password Management Guideline, April 12, 1985.
NCSC-TG-017, A Guide to Understanding Identification and Authentication in Trusted Systems, September 1, 1991.
Identification and Authentication Procurement Considerations
This subject is discussed in Volume 1, Chapter 3 of the Procurement Guideline Series.
Technology has provided techniques and products that vary greatly in terms of reducing attack risk while satisfying these requirements. The procurement initiator should ensure that the solution that satisfies the requirements is also state--of--the--art in level of protection and consistent with the requirements of this particular application.
To be effective, authentication mechanisms must uniquely and unforgeably identify an individual. Identification and authentication data is vulnerable to interception by an intruder interposed between a user and the TCB. Compromise may result from mishandling off--line versions of the data (e.g., backup files, fault induced system dumps, or listings). Even a one--way encrypted file can be compared with an encryption dictionary of probable authentication data, if the encryption algorithm and key are known.
(Classes B1--A1) Authorizations include functional roles assigned to individuals. Most roles can only be occupied by one person at a time. A role has its own set of authorizations that are normally different than the authorizations given to the individuals who can assume the role. An individual should not be allowed to assume a role and operate as an individual at the same time.
If passwords are to be used, an automatic password generator is strongly recommended. If users are allowed to pick their own specific authenticators, their behavior is stereotypical enough to permit guessing or reproducing. Password generators are available that have been endorsed by NSA and can be obtained as Government off--the--shelf items.
Password aging is an important consideration that can be enforced administratively or by the identification/authentication function.
Smart cards and biometric approaches are effective, especially when they augment a password approach.
Whenever the subject is an operating computer program (i.e., a process), that process shall be directly associated with just one individual user, i.e., the person being served by the process. If the process is a system--owned process (e.g., a background process such as a print spooler), the person associated with the process is generally considered to be the Security Officer, the System Administrator, or the operator who initiated the process. The security level and other subject data that can influence access decisions shall be within the range of personnel security clearances associated with the individual user.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class B2, repeat TCSEC Section 3.2.2.1.1.
For Class B3, repeat TCSEC Section 3.3.2.1.1.
For Class A1, repeat TCSEC Section 4.1.2.1.1.
Important References
None
Trusted Path Procurement Considerations
It is important to note that the intent is to protect identification and authentication data at the B2 level, while at the B3 and A1 levels all intercommunications between the TCB and the user can be protected.
Technology is providing products that greatly reduce the possibility of successful attacks involving the trusted path. The procurement initiator should ensure that the solution that satisfies the requirements is also state- -of--the--art in level of protection.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class C2, repeat TCSEC Section 2.2.2.2.
For Class B1, repeat TCSEC Section 3.1.2.2.
For Class B2, repeat TCSEC Section 3.2.2.2.
For Class B3, repeat TCSEC Section 3.3.2.2.
For Class A1, repeat TCSEC Section 4.1.2.2.
Important References
Note: References are for information only and, unless specified elsewhere, are not to be taken as requirements.
NCSC-TG-001, A Guide to Understanding Audit in Trusted Systems, June 1, 1988.
Audit Procurement Considerations
The option should exist that either some maximum of security related activities be audited or that the System Administrator select events to be audited based on overhead considerations.
An audit control switch available to the System Administrator can allow selection of audit levels, but never to allow less than some required minimum as determined by the DAA.
A requirement exists that authorized personnel shall be able to read all events recorded on the audit trail. A selection option is required that may either be a preselection or a post selection option. The preselection option limits the audit data recorded. The post selection option reduces the data analyzed from that recorded.
Switches and options must not violate the requirements and intent of the TCSEC.
The audit information should be sufficient to reconstruct a complete sequence of security related events. Audit analysis tools can greatly enhance the efficiency of the audit control function for the System Administrator. (See NCSC-TG-001 for further discussion.)
The capability should be provided to prevent System Administrator and Security Officer functions from turning off auditing or modifying those results.
Only the System Administrator or Security Officer should be able to select what is to be audited from other events.
(Classes B3--A1) The requirement to "monitor the occurrence or accumulation of security auditable events that may indicate an imminent violation of security policy" is subject to interpretation. It is the topic of an entire subfield of security known as intrusion detection. The DAA must determine what is reasonable in the context of the particular application.
(Classes B3--A1) "If the occurrence or accumulation of these security relevant events continues, the system shall take the least disruptive action to terminate the event." The approach taken is very application peculiar and the DAA must further specify the action to be taken.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class C2, repeat TCSEC Section 2.2.3.1.1.
For Class B1, repeat TCSEC Section 3.1.3.1.1.
For Class B2, repeat TCSEC Section 3.2.3.1.1.
For Class B3, repeat TCSEC Section 3.3.3.1.1.
For Class A1, repeat TCSEC Section 4.1.3.1.1.
Important References
None
System Architecture Procurement Considerations
"Domain" as used in the TCSEC refers to the set of objects a subject has the ability to access. It is, for example, the protection environment in which a process is executing. Domain is sometimes also called "context" or "address space."
Protection granularity can be an issue. Finer granularity (e.g., a few bytes) is ideal for providing precise control (down to the byte or word level), but requires a significant amount of computer overhead to maintain. The trade--off usually made is to have coarser granularity (e.g., 1024 byte blocks) to reduce hardware complexity and retain acceptable performance. (See Volume 1, Chapter 3 of this guideline series.)
An important consideration is sensitivity label mapping to protection domain mechanisms. Hardware features (usually called "keys") allow the TCB to associate specific hardware "registers" with the main memory areas (domains) they are protecting. There should be sufficient types and numbers of "registers" to ensure the number of sensitivity labels for information in the system can be adequately mapped. Common ways to achieve these capabilities are through "Descriptor Base Registers," "Bounds Registers," and "Virtual Memory Mapping Registers," although other approaches may also be used.
Asynchronous events are not predictable (e.g., arrival of a message, the printer running out of paper, or communications link errors). Asynchronous event mechanisms are hardware features that handle the unpredictable, usually by "interrupting" the processor. Once interrupted, the processor then deals with the event. Interpretation of DoD 5200.28-STD will probably require hardware features that will cause the processor to recognize and respond to specific asynchronous events, such as "security policy violations" (in DoD 5200.28-STD phrasing, violations of the Simple Security Property or Star Property). Unless hardware features support these properties, software must interpret the results of every operation, causing a severe performance penalty. The penalty may come into conflict with mission performance requirements.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class C2, repeat TCSEC Section 2.2.3.1.2.
For Class B1, repeat TCSEC Section 3.1.3.1.2.
For Class B2, repeat TCSEC Section 3.2.3.1.2.
For Class B3, repeat TCSEC Section 3.3.3.1.2.
For Class A1, repeat TCSEC Section 4.1.3.1.2.
Important References
None
System Integrity Procurement Considerations
System integrity requirements must be satisfied in the operational system, not just demonstrated as part of test. The DAA shall establish the frequency with which system integrity validation must be accomplished and it should be incorporated into procedural security.
(Classes B2--A1) Wherever possible, covert channels identified by the covert channel analysis with bandwidths that exceed a rate of one bit in ten seconds should be eliminated or the TCB should provide the capability to audit their use.
Important References
Note: References are for information only and, unless specified elsewhere, are not to be taken as requirements.
For Class B2, TCSEC Section 3.2.3.1.3.
For Class B3, TCSEC Section 3.3.3.1.3.
For Class A1, TCSEC Section 4.1.3.1.3.
TCSEC Section 8.0, "A Guideline on Covert Channels."
Covert Channel Procurement Considerations
The TCSEC only requires the analysis of covert channels, tradeoffs involved in restricting the channels, and identification of the auditable events that may be used in the exploitation of known channels. Here it requires that some action be taken for correcting them. The procurement initiator should clearly specify in the RFP what will be expected of a contractor. Proposal evaluation should further determine what is intended by the bidder. This issue must be clearly understood by the Government and the bidder and documented in the specification before an award is made.
Covert channel auditing and control mechanisms can vary widely from one system to another. In general, the ability to meet both performance and security requirements increases as the security protection mechanisms become more flexible.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the specification portion of the RFP verbatim:
For Class C2, repeat TCSEC Section 2.2.3.1.4.
For Class B1, repeat TCSEC Section 3.1.3.1.4.
For Class B2, repeat TCSEC Section 3.2.3.1.4.
For Class B3, repeat TCSEC Section 3.3.3.1.4.
For Class A1, repeat TCSEC Section 4.1.3.1.4.
Important References
Note: References are for information only and, unless specified elsewhere, are not to be taken as requirements.
NCSC-TG-015, A Guide to Understanding Trusted Facility Management, October 18, 1989.
Trusted Facility Management Procurement Considerations
The TCSEC addresses System Administrator functions and operator functions and specifically identifies the Automated Data Processing (ADP) System Administrator. The roles and individuals must be specifically identified for this particular application and the RFP should show the mapping of particular roles and those called out in the TCSEC. For example, if the Security Officer and the ADP System Administrator are one and the same, it should be stated or only one title should be used consistently throughout the RFP. If there is more than one operator role, this should be identified.
The acquisition authority must carefully consider the division of functions between the operator and the System Administrator because the cost of changing them is often high.
(For B3 through A1) Based on the recommendations of a trusted recovery decision, mechanisms shall be provided to assure that, along with procedures, recovery without a protection compromise is obtained after a computer system failure or other discontinuity.
Important References
Note: References are for information only and, unless specified elsewhere, are not to be taken as requirements.
For Class B3, TCSEC Section 3.3.3.1.5.
For Class A1, TCSEC Section 4.1.3.1.5.
NCSC-TG-022, A Guide to Understanding Trusted Recovery in Trusted Systems, December 30, 1991.
Trusted Recovery Procurement Considerations
Satisfactory recovery can have significantly different meaning to different applications because of differences in the time criticality of operational results. The procurement initiator must be certain that the true operational requirements for this particular application are reflected in the RFP.
Note that satisfaction of this requirement does not guarantee data recovery. It keeps the system from blindly compromising data and allows the System Administrator to reach a known good point in the process where other mission mechanisms (e.g., backup) can safely proceed. Trusted recovery does not obviate the need for responsible backup procedures and practices.
The bidder shall consider and/or recommend security support other than COMPUSEC, especially physical security, emission security, and communications security, that shall also be used to protect the system.
The system shall be shown to be compatible with all operational security requirements identified, ensuring that there is nothing in the design of the proposed solution to preclude their satisfaction.
Important References
None
Operational Security Procurement Considerations
The procurement initiator, working with the DAA, shall specify the operational security specifications in this section of the RFP. The following candidate list should be considered along with any others identified:
Division/Class to be satisfied.
Security levels supported.
Security clearances supported.
Security mode(s) to be supported.
Categories, compartments, and caveats supported with rules of support.
Statement of all interfaces and any interface policy required to be supported.
Statement of operational positions and responsibilities of each associated with security.
Statement concerning the intended frequency of mechanism integrity checking during operations.
Minimum audit functionality to be supported at all times, plus other increasing levels of audit support and rules for their use.
Maximum number of users.
Intended hours of operations.
Hard copy output.
Environment for software development.
For each task, the requirements of the SOW describe the work the contractor is expected to do. The specification of the deliverable is accomplished within a CDRL and its associated DID. Here we have provided sample CDRL numbers to correspond with Section F.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the Statement of Work portion of the RFP verbatim:
For Class B2, repeat TCSEC Section 3.2.3.1.3.
For Class B3, repeat TCSEC Section 3.3.3.1.3.
For Class A1, repeat TCSEC Section 4.1.3.1.3.
(Classes B2--A1)
The contractor shall conduct an analysis of all auditable events that may occur in the exploitation of the identified covert channels.
The contractor shall conduct an analysis of identified covert channels and bandwidths that are non detectable by the auditing mechanisms. The contractor shall determine the auditability of channels that have a bandwidth in excess of one bit in ten seconds.
A report of the results of these analyses shall be provided in the form of a Covert Channel Analysis Report, written in accordance with CDRL 010.
Important References
Note: References are for information only and, unless specified elsewhere, are not to be taken as requirements.
TCSEC Section 8.0 "A Guideline on Covert Channels."
Covert Channel Analysis Procurement Considerations
None
(Classes B3--A1)
The contractor shall conduct an analysis of the computer system design to determine procedures and/or mechanisms that need to be activated in case of a system failure or other discontinuity.
Where procedures are recommended they should be thoroughly documented in CDRL 002, Trusted Facility Manual.
Where design is recommended it is delivered in the form of system design in accordance with CDRL 005, Formal Security Policy Model; CDRL 006, Descriptive Top Level Specification; CDRL 008, Design Specification; and CDRL 012, Security Test Plan.
Important References
Note: References are for information only and, unless specified elsewhere, are not to be taken as requirements.
For Class B3, TCSEC Section 3.3.3.1.5.
For Class A1, TCSEC Section 4.1.3.1.5.
NCSC-TG-022, A Guide to Understanding Trusted Recovery in Trusted Systems, December 30, 1991.
TCSEC Section 5.3.3, "Assurance Control Objective," p. 63.
Trusted Recovery Procurement Considerations
None
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the Statement of Work portion of the RFP verbatim:
For Class C2, repeat TCSEC Section 2.2.3.2.1 and TCSEC Section 10.1.
For Class B1, repeat TCSEC Section 3.1.3.2.1 and TCSEC Section 10.2.
For Class B2, repeat TCSEC Section 3.2.3.2.1 and TCSEC Section 10.2.
For Class B3, repeat TCSEC Section 3.3.3.2.1 and TCSEC Section 10.2.
For Class A1, repeat TCSEC Section 4.1.3.2.1 and TCSEC Section 10.3.
The contractor shall deliver test results in the form of Test Reports in accordance with CDRL 014. A final summary Test Report is called out under Section C.3.9, "Test Documentation Statement of Work."
Important References
Note: References are for information only and, unless specified elsewhere, are not to be taken as requirements.
NCSC-TG-002, Trusted Product Evaluations: A Guide for Vendors, June 22, 1990.
NCSC-TG-019, Trusted Product Evaluation Questionnaire, May 2, 1992.
NCSC-TG-028, Assessing Controlled Access Protection, May 25, 1992.
Security Testing Procurement Considerations
Many of the statements in the security testing requirements are subject to interpretation, (e.g., "relatively resistant to penetration," "consistency with top level specifications," "no more than a few correctable flaws," and "reasonable confidence that few remain"). The procurement initiator in the RFP must attempt to convey in any manner possible what will be expected by the Government, not only in satisfying the security testing requirement, but in terms of meeting the certification evaluation. Similarly, in evaluation of the bidder's response to testing requirements of the RFP, the Government must be very careful to understand that the contractor understands what is required. As an example, there is a great advantage in identifying who will conduct the penetration analysis (B2 and above) and how the results of that penetration will be dealt with. A clear understanding must exist and be documented before an award is made.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the Statement of Work portion of the RFP verbatim:
For Class B1, repeat TCSEC Section 3.1.3.2.2.
For Class B2, repeat TCSEC Section 3.2.3.2.2.
For Class B3, repeat TCSEC Section 3.3.3.2.2.
For Class A1, repeat TCSEC Section 4.1.3.2.2.
(Class B1)
Documentation developed under CDRL 004, Informal Security Policy Model, and CDRL 008, Design Specification, shall be maintained as a result of this effort with updates delivered according to the CDRL.
Initial delivery of CDRL 004, Informal Security Policy Model, and CDRL 008, Design Specification, is addressed in Section C.3.10, "Design Documentation Statement of Work." Subsequent deliveries shall be delivered under this task.
(Class B2)
Documentation developed under CDRL 005, Formal Security Policy Model; CDRL 006, Descriptive Top Level Specification; and CDRL 008, Design Specification; shall be maintained as a result of this effort with updates delivered according to the CDRL.
Initial delivery of CDRL 005, Formal Security Policy Model; CDRL 006, Descriptive Top Level Specification; and CDRL 008, Design Specification; is addressed in Section C.3.10, "Design Documentation Statement of Work." Subsequent deliveries shall be delivered under this task.
(Class B3)
Documentation developed under CDRL 005, Formal Security Policy Model; CDRL 006, Descriptive Top Level Specification; and CDRL 008, Design Specification; shall be maintained as a result of this effort with updates delivered according to the CDRL.
Documentation resulting from this effort shall be provided in accordance with CDRL 009, Trusted Computing Base Verification Report.
Initial delivery of CDRL 005, Formal Security Policy Model; CDRL 006, Descriptive Top Level Specification; and CDRL 008, Design Specification; is addressed in Section C.3.10, "Design Documentation Statement of Work." Subsequent deliveries shall be delivered under this task.
(Class A1)
Documentation developed under CDRL 005, Formal Security Policy Model; CDRL 006, Descriptive Top Level Specification; CDRL 007, Formal Top Level Specification; and CDRL 008, Design Specification; shall be maintained as a result of this effort with updates delivered according to the CDRL.
Documentation resulting from this effort shall be provided in accordance with CDRL 009, Trusted Computing Base Verification Report.
Initial delivery of CDRL 005, Formal Security Policy Model; CDRL 006, Descriptive Top Level Specification; CDRL 007, Formal Top Level Specification; and CDRL 008, Design Specification; is addressed in Section C.3.10, "Design Documentation Statement of Work." Subsequent deliveries shall be delivered under this task.
Important References
Note: References are for information only and, unless specified elsewhere, are not to be taken as requirements.
NCSC-TG-014, Guidelines for Formal Verification Systems, April 1, 1989.
Design Specification and Verification Procurement Considerations
If there is a multifaceted policy (e.g., both mandatory access control and discretionary access control policies), then all facets must be represented in the Top Level Specification and Security Model.
(Classes B2--A1) To broaden the audience, there is often an advantage to requiring an informal policy model as well as a formal one.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the Statement of Work portion of the RFP verbatim:
For Class B2, repeat TCSEC Section 3.2.3.2.3.
For Class B3, repeat TCSEC Section 3.3.3.2.3.
For Class A1, repeat TCSEC Section 4.1.3.2.3.
(Classes B2--A1) Prepare and deliver the TCB Configuration Management Plan in accordance with CDRL 011. One section of this document is originated under Section C.3.6, "Trusted Distribution Statement of Work."
Important References
Note: References are for information only and, unless specified elsewhere, are not to be taken as requirements.
NCSC-TG-006, A Guide to Understanding Configuration Management in Trusted Systems, March 28, 1988.
Configuration Management Procurement Considerations
Master copies should be protected at the level of the operational data for which it will be used.
(Classes B2--A1) The maintenance of a consistent mapping between code and documentation may require further definition (e.g., including the response time for bringing documentation up to date with changes and the exact amount of effort to go into this requirement).
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the Statement of Work portion of the RFP verbatim:
For Class A1, repeat TCSEC Section 4.1.3.2.4.
These procedures shall be delivered as a section on trusted distribution as a part of the Trusted Computing Base Configuration Management Plan in accordance with CDRL 011. The rest of the document is developed under Section C.3.5, "Configuration Management Statement of Work."
Important References
Note: References are for information only and, unless specified elsewhere, are not to be taken as requirements.
NCSC-TG-008, A Guide to Understanding Trusted Distribution in Trusted Systems, December 15, 1988.
Trusted Distribution Procurement Considerations
None
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the Statement of Work portion of the RFP verbatim:
For Class C2, repeat TCSEC Section 2.2.4.1.
For Class B1, repeat TCSEC Section 3.1.4.1.
For Class B2, repeat TCSEC Section 3.2.4.1.
For Class B3, repeat TCSEC Section 3.3.4.1.
For Class A1, repeat TCSEC Section 4.1.4.1.
(Classes C2--A1) The contractor shall produce and deliver the Security Features Users Guide in accordance with CDRL 001.
Important References
Note: References are for information only and, unless specified elsewhere, are not to be taken as requirements.
NCSC-TG-026, A Guide to Writing the Security Features User's Guide for Trusted Systems, September 1991.
Security Features User's Guide Procurement Considerations
The contractor should conduct a security engineering analysis to determine user functionality related to security. This analysis should also develop the user guidelines for consistent and effective use of the protection features of the proposed solution. This analysis should address a description of expected system reaction to security--related events.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the Statement of Work portion of the RFP verbatim:
For Class C2, repeat TCSEC Section 2.2.4.2.
For Class B1, repeat TCSEC Section 3.1.4.2.
For Class B2, repeat TCSEC Section 3.2.4.2.
For Class B3, repeat TCSEC Section 3.3.4.2.
For Class A1, repeat TCSEC Section 4.1.4.2.
(Classes C2--A1) The contractor shall deliver the Trusted Facility Manual in accordance with CDRL 002.
Important References
Note: References are for information only and, unless specified elsewhere, are not to be taken as requirements.
NCSC-TG-027, Information System Security Officer Guideline, June 1991.
Trusted Facility Manual Procurement Considerations
The contractor should conduct an analysis to identify the functions performed by the role of the System Administrator. This analysis should identify all nonsecurity functions that can be performed in the System Administrator role. The contractor should conduct an analysis to determine, for the operator and System Administrator, the specific cautions about functions and privileges that should be controlled while running a secure facility and the specific interactions of the protection features. The contractor should also conduct an engineering analysis of the system to identify all information and events to be audited, including rationale (i.e., cost, conformance to requirements, security, and performance impacts) for the selection of each item. The contractor should also identify the types of events that occur within the system that are not audited, along with reasons for not auditing them.
C.3.9 TEST DOCUMENTATION STATEMENT OF WORK
Text of the Statement of Work
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the Statement of Work portion of the RFP verbatim:
For Class C2, repeat TCSEC Section 2.2.4.3.
For Class B1, repeat TCSEC Section 3.1.4.3.
For Class B2, repeat TCSEC Section 3.2.4.3.
For Class B3, repeat TCSEC Section 3.3.4.3.
For Class A1, repeat TCSEC Section 4.1.4.3.
(Classes C2--A1)
The contractor shall deliver the Security Test Plan in accordance with CDRL 012.
The contractor shall deliver the Test Procedure in accordance with CDRL 013.
The contractor shall deliver the Test Report in accordance with CDRL 014 using as input Test Reports generated in Section C.3.3, "Security Testing Statement of Work."
Important References
None
Security Testing Procurement Considerations
The contractor should analyze the sensitivity of information processed on the delivered system, the desired mode of operation, and the DAA's certification requirements to assist in developing the test approach.
If an entity other than a contractor is to do the Security Testing and Test Report, this should be clarified in the Statement of Work. The Test Plan (which is a management tool detailing who does what and when) and Procedures (which is a step--by--step testing script) should be prepared by the contractor to ensure that specific knowledge of the TCB implementation can be included in the development. These may later be augmented or modified by the entity doing the testing under separate contract or agreement.
For B2 and above, penetration testing must consider the specific operational environment and threat model of this particular application.
Where the given Division/Class is applicable, the corresponding section of the TCSEC should be repeated in the Statement of Work portion of the RFP verbatim:
For Class C2, repeat TCSEC Section 2.2.4.4.
For Class B1, repeat TCSEC Section 3.1.4.4.
For Class B2, repeat TCSEC Section 3.2.4.4.
For Class B3, repeat TCSEC Section 3.3.4.4.
For Class A1, repeat TCSEC Section 4.1.4.4.
(Class C2)
Documentation resulting from this effort shall be provided in accordance with CDRL 003, Philosophy of Protection Report, and CDRL 008, Design Specification.
(Class B1)
Documentation resulting from this effort shall be provided in accordance with CDRL 003, Philosophy of Protection Report; CDRL 004, Informal Security Policy Model; and CDRL 008, Design Specification.
Initial delivery of CDRL 004 and CDRL 008 is addressed under this task. Subsequent deliveries shall be delivered under Section C.3.4, "Design Specification and Verification Statement of Work."
Initial delivery of CDRL 008 is addressed under this task. Subsequent deliveries shall be delivered under Section C.3.4, "Design Specification and Verification Statement of Work."
(Class B2)
Documentation resulting from this effort shall be provided in accordance with CDRL 003, Philosophy of Protection Report; CDRL 005, Formal Security Policy Model; CDRL 0