Volume 3/4
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
28 February 1994
Patrick R. Gallagher, Jr.
Director
National Computer Security Center
Acknowledgement is also given to the primary author, Joan Fowler, Grumman Data Systems (GDS); and the contributions of Dan Gambel, GDS; Nicholas Pantiuk, GDS; Virgil Gibson, GDS; Yvonne Smith, GDS; Judy Hemenway, GDS and Howard Johnson, Information Intelligence Sciences, Inc.
Organizations that were particularly helpful in providing constructive reviews
and advice besides many NSA organizations, included: Contel Federal Systems; CTA, Inc.; DCA; DLA; DOE; GSA; MITRE; NISMC; USA, CECOM; USA, OSA; USAF, AFCC; USAF, AFCSC; USAF, USCINCPAC/C3; USMC; USN, ITAC; USN, NCTC; and USN, NISMC.
Special thanks to Carol Oakes, Senior Technical Editor, MITRE, for her
assistance with the final editing of this guideline.
Table 2.Summary of DID Subsections to be Deleted for Each Security
Document 35
Figure 2.Test Documentation Correspondence 13
Figure 3.Contract Data Requirements List Form (DD Form 1423-1) 16
This guideline is Volume 3 of a 4-volume series of Automated Information System (AIS) procurement guidelines produced by the National Computer Security Center (NCSC). The complete set of documents is intended to help clarify the complex issues associated with the acquisition process relevant to computers, security, and contracting by explaining to procurement initiators specification and Statement of Work (SOW) procedures to follow for including computer security requirements in procurements. Volume 1, An Introduction to Procurement Initiators on Computer Security Requirements, provides guidance to promote the understanding of requirements and guide the acquisition of secure products within the DoD. Volume 2, Language for RFP Specifications and Statements of Work - An Aid to Procurement Initiators, provides SOW contract language for the specification of Evaluated Products List (EPL) commercial products or their equivalents. Volume 4, How to Evaluate a Bidder`s Proposal Document - An Aid to Procurement Initiators and Contractors, provides specific guidance for a procurement initiator in writing a Request for Proposal for computer security systems.
The material contained herein as Volume 3 specifies the data deliverables to meet security assurance needs by providing guidance on Contract Data Requirements Lists (CDRLs) and their associated Data Item Descriptions (DIDs).
This guideline is intended for use by DoD procurement initiators when considering the acquisition of trusted computer products. The emphasis of the guideline is on the data requirements for products.
Many trusted data requirements dictate the documentation required for integration, testing, assurance, certification, and accreditation. Additionally, there are numerous documentation requirements for general software (e.g., Defense System Software Development, Military Standard (MIL-STD)-2167A). This guideline addresses only the data requirements that are specifically required by the TCSEC.
Finally, this guideline is geared toward the data requirements involved in the acquisition of Evaluated Products List (EPL) Commercial Off-the-Shelf (COTS) packages. However, the data requirements are the same whether the product is on the EPL or not. Therefore, this guideline is applicable to the data requirements for any acquisition in which security is a factor.
The following limitations should be noted when using this guideline:
*The procurement initiator is responsible under Enclosure 4 of Department of Defense Directive (DoDD) 5200.28 for assessing the minimum Automated Information System (AIS) computer-based security requirements for the mission profile being acquired. The result of this assessment is a TCSEC Class that is to be used to index into the appropriate sections of this guideline. It is not sufficient only to quote a TCSEC Class in Requests for Proposal (RFPs) -- all of the individual requirements must be included in the RFP.
*This is not a complete acquisition guideline; it is a guideline to procure only security-related documentation. Only the requirements of the CDRL and DID sections of an RFP are addressed in this guideline.
*This document is not a revision or interpretation of the TCSEC; it is a reformatting and reordering into a form suitable for DIDs and the use of these DIDs. There is no intent to change the TCSEC or any vendor-specific interpretations of the TCSEC in this document.
This guideline will facilitate the acquisition and proliferation of products on the EPL. The guideline is intended to enable the procurement initiator to obtain security documentation for those EPL products that are available and have documentation.
If a product is evaluated as meeting a TCSEC class, then its evaluation and evaluation documentation remains valid (i.e., nothing in this guideline is to be interpreted as invalidating an EPL evaluation). However, since products not yet on the EPL may also be used to satisfy an acquisition, the cost advantage of having completed the EPL evaluation documentation provides an incentive for industry to submit products for evaluation. Once evaluated and on the EPL, the products can be proposed at a lower risk and cost in meeting government requirements at certain levels and, depending on the product, without modification. This approach provides a competitive advantage to those companies that expend the effort to obtain product evaluation on the EPL with the associated evaluation documentation, and provides a cost savings to the government.
The acquisition process (as defined in DoDD 5000.1) is a directed, funded effort that is designed to provide a new or improved capability in response to a validated need. The directive establishes a disciplined approach for translating operational needs into a stable, affordable program.
For the purposes of this guideline, the most important process in acquiring documentation for trusted products is the definition of the documentation required. This is done in the RFP, which is the most widely used document for acquisitions. The key components of the RFP package are description/specification; special contract requirements; list of documents, exhibits, and other attachments; and instructions, conditions, and notices to offerors.
The description/specification section of an RFP describes the mandatory technical and performance requirements to the contractor. It contains a Statement of Work (SOW) that identifies the specific tasks the contractor will perform during the contract period as well as the specification containing the definition/requirements of the acquisition. (This definition of the entity being acquired becomes the target for the security documentation.) The SOW also provides the opportunity to require delivery of information or specific data. This is done by referencing the appropriate CDRL number in the SOW paragraph. The information or specific data are a by-product of the actual SOW task. Thus, each SOW task normally refers to one or more CDRL items. The data referenced by the CDRL could be a list, plan, manual, computer-produced file or program, or a report.
The CDRL identifies the data that the contractor is required to prepare and deliver as part of the contract. The CDRL is also the vehicle by which data delivery dates are established, as well as providing delivery instructions and any other special requirements (e.g., number of copies). Each CDRL refers, in turn, to one DID. The DID should be referred to by the latest revision number and the name.
The DID specifies the actual content and format of the deliverable data, and therefore it drives the effort required to prepare the data item. In most acquisitions, the government reviews the documentation delivered with the product or service and uses it to assess whether all contractual requirements have been satisfied. Currently, about 2,000 standard approved DIDs exist. These DIDs were created by various DoD offices, forwarded through channels to the DoD Data Administrator, and subsequently approved for general use in contracts.
The DoD guide to the available DIDs is published semiannually as the Acquisition Management Systems and Data Requirements Control List (AMSDL). The AMSDL lists all standard DIDs in three different sequences: numerical, keyword (indexed), and functional area program category. It also provides a list of superseded and deleted DIDs. The DID numbers on the AMSDL are frequently changing when new DIDs supersede other DIDs. Less frequently, DID names change. It is a good habit to use both the DID number and name whenever referring to a DID.
The DIDs needed for security-relevant documentation are very specific in nature. Only recently has the AMSDL listed all the DIDs required to satisfy TCSEC requirements for documentation. We have included these DIDs in Appendix B of this guideline for the reader's convenience.
The special contract requirements section of the RFP contains clauses that are unique and specially tailored for each acquisition. The attachments section contains a list of all documents, exhibits, attachments, and other forms used to build and execute the RFP. There are usually a series of attachments, each one dedicated to a list of specific items. For example, the CDRLs would be one attachment. The actual exhibits and attachments, including the CDRLs and DIDs, are physically appended to the end of the RFP.
Finally, the instructions section of the solicitation contains the instructions, conditions, and notices to offerors of the acquisition, covering such areas as proposal format, oral presentations, and the proposal preparation instructions.
Appendix A contains sample CDRLs for each relevant TCSEC class of each security document. These CDRLs can be used by the procurement initiator as sample CDRLs to include in an RFP. The italicized data should be replaced with project information. The blocks on the sample CDRLs that have been left blank should be filled in with the appropriate information for a specific RFP. Section 3 provides the guidance for completing these blocks, as well as a description of all of the blocks on the CDRL. Block 16 of the sample CDRLs is especially noteworthy because it contains all pertinent data item information not specified elsewhere on the form and any required amplifications of other block inputs. This block can be used as shown in the sample.
Appendix B contains 14 AMSDL approved Security DIDs that describe all of the documentation required by the TCSEC. Each DID can be included in an RFP with a corresponding CDRL to tailor the DID for the specific RFP.
Appendixes C, D, and E contain the References, Glossary, and Acronyms, respectively. These appendixes provide a common understanding of the terms and references used in this guideline.
The security documentation requirements in the TCSEC are defined for each class. As with the functional requirements for trusted products, the documentation requirements for the most part are cumulative. This means that generally the documentation requirements at the lower class levels are usually also required at the upper class levels, with additional requirements added at the upper class levels. This is not always true for a specific document.
The level of classification of all of these security documents is determined by the classification of the processing and information being described. Naturally, if the source code or design that is described in the security documentation is classified, then the documents describing this source code or design in detail will also be classified. At times, no single portion of the source code is classified, but the combination of all the source code is classified. If this is the case, then the combination of all of the detailed documentation would be classified.
Documentation required by the TCSEC falls into three high-level categories: Operational Manuals, Design Documentation, and Assurance Documentation. The descriptions below for each of these three categories discuss the general contents of the documents included in the category.
The TFM explains the roles of the Security Administrator, System Administrator, and System Operator in establishing, operating, and maintaining a secure environment. It describes the procedures for selecting security options to ensure that the operational requirements will be met in a secure manner. The level of detail of the TFM spans the gap between the user-oriented SFUG and the security engineer-oriented design documentation.
The Philosophy of Protection Report provides a description of the security policy for the product. It also contains the overall high-level design of a TCB, delineating each of the protection mechanisms employed to enforce the policy.
An informal security policy model is an abstract representation of a TCB and the security policy enforced by the TCB. The Informal Security Policy Model document contains the informal security policy model, its associated convincing assurance arguments, and supporting explanations and documentation for both the model and assurance arguments. The model consists of two segments: (1) an informal description of the policy that is to be enforced by the TCB, and (2) an informal description of the abstract protection mechanism(s) within the TCB, which enforce the described policy. The model includes the representation of the initial state of the TCB; the representation of subjects, objects, modes of access, and security labels; the set of security properties enforced by the TCB; and the representations of the operations performed.
A formal security policy model is a mathematically precise abstract representation of a security policy and the abstract protection mechanisms that enforce the policy. To be acceptable as a basis for a TCB, the model must be supported by formal proof. The Formal Security Policy Model document contains the formal security policy model, its associated proofs, and the supporting explanations and documentation for both the model and proofs. The model contained in the Formal Security Policy Model document consists of two segments: (1) the mathematical representation of the policy, and (2) the mathematical representation of the abstract protection mechanism(s) within the TCB.
The DTLS is a top-level specification using English language descriptions. It completely and accurately describes the TCB in terms of exceptions, error messages, and effects. The DTLS is an accurate description of the TCB interface. It describes the security capabilities in functional terms and concepts, and therefore takes the broad form of a "security features functional description." The DTLS is traceable to the formal security policy model.
The FTLS is a mathematically precise abstract representation of the TCB. The TCSEC requires that the FTLS provide an accurate description of the TCB interface; describe the TCB in terms of exceptions, error messages, and effects; and include hardware or firmware elements if their properties are visible at the TCB interface. The FTLS document contains the Formal Top-Level Specification, its associated proofs and assurance arguments, and supporting explanations and documentation for the specification, proofs, and assurance arguments.
The Design Specification demonstrates that correct implementation and enforcement of the security policy exists in the TCB. It explains the protection mechanisms of the TCB to the extent that the effect of a change on the TCB can be evaluated prior to a change being performed. The Design Specification contains enough information so that it may serve as a guide to understanding the implementation of the TCB.
At the TCB Class B3 level, the TCB Verification Report provides the correspondence between the DTLS and the implementing source code to demonstrate that the TCB has been correctly and accurately implemented. At the TCB Class A1 level, the FTLS is mapped to the source code to demonstrate that the FTLS has been accurately implemented in the selected programming language (and hardware).
The CCA Report is a description of the analysis of covert channels. Covert channels can be used to circumvent the access control features built into a TCB. There are two different types of malicious covert channels: storage channels and timing channels. These channels present opportunities to maliciously exploit characteristics of the TCB, or operating system-provided functions. By doing so, information can bypass mandatory access controls. The exploitation of covert channels causes unintentional side effects and unavoidably visible system calls/acknowledgments. For TCB classes B2, B3, and A1, covert channels must be identified, removed if possible, and their activity audited.
The TCB CM Plan details the configuration management procedures for a TCB. It addresses hardware, firmware, software, testing, and documentation. The TCB CM Plan indicates how the security requirements baseline will be maintained. It provides assurance that the security protections are safe from the introduction of improper hardware, firmware, and software during the developmental and operational life of the system. Finally, it describes the configuration control process, configuration management procedures, and review and approval procedures for changes to the security design implementation of the TCB.
The security test documentation consists of three documents, the Security Test Plan, Security Test Procedures, and the Security Test Report. The Security Test Plan provides the strategy to test the security mechanisms of the TCB. It also documents in detail the plan for conducting security tests (e.g., what security features will be tested, why they will be tested, and how they will be tested). Essentially, the Security Test Plan explains how the test results will be analyzed to show that the TCB will satisfy the security requirements. The Security Test Procedures identify the step-by-step testing operations to be performed in sufficient detail to permit total duplication of the test program. The document identifies the items to be tested, the test equipment and support required, the test conditions to be imposed, the parameters to be measured, and the pass/fail criteria against which the test results will be measured. Finally, the Security Test Report describes the tests performed, discusses the test analyses, and provides the results of the tests. The report includes all recorded test data or logs.
Table 1: Documentation Requirements by TCSEC Class
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DOCUMENTATION TCSEC CLASS
C2 B1 B2 B3 A1
Security Features User`s Guide X X X X X
Trusted Facility Manual X X X X X
Philosophy of Protection X X X X X
Informal Security Policy Model Y
Formal Security Policy Model Y X X X
Descriptive Top-Level Specification X X X
Formal Top-Level Specification X X X
Design Specification X X X X X
TCB Verification Report X X
Covert Channel Analysis Report X X X
TCB Configuration Management Plan X X X
Security Test Plan X X X X X
Test Procedure X X X X X
Test/Inspection Reports X X X X X
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X = Required at the TCSEC Class
Y = For TCSEC Class B1, either an informal or a formal security policy model is required
Table 1 cross references the security documentation described above to the TCSEC classes. An "X" indicates the class at which the TCSEC contains a requirement for the documentation. For those documents which are required at multiple classes, the specific requirements for the document change at each of the higher classes.
As reflected in Table 1, the required class for all of the security documentation (except the informal and formal security policy model) is explicitly defined in the TCSEC. The TCSEC requires either an informal or a formal security policy model at TCSEC Class B1. The determination of which security policy model should be required at TCSEC Class B1 should be made by the program office for each specific program.
Whether or not the product is on the EPL, generic user manuals are always available for any COTS product. These user manuals provide information on all of the features of the product, usually not just the security features. If the product requires an administrator, administrator manuals will be available. Design and test documentation, either for general features or security features, usually are not provided with COTS packages unless expressly purchased.
If the COTS product is on the EPL, a whole spectrum of TCSEC documents will be available for the class at which the product was evaluated. However, these documents (except the user and administrator manuals) are not normally included in the standard delivery of the product and must be specifically ordered for each procurement. Since these documents may be highly proprietary to the company developing the COTS product, the cost of the detailed documentation may be prohibitive to an acquisition. Careful assessment of the requirement for the detailed product documentation, particularly since the product is on the EPL, must be made to determine the cost-benefit trade-off for this documentation.
If the COTS product is under evaluation by the National Computer Security Center (NCSC), but has not yet passed evaluation, the stage that the product has reached in the evaluation will determine the amount of security documentation readily available for the product. The same caveats discussed above for COTS products on the EPL apply to those undergoing evaluation. However, the products which are under evaluation are by their very nature more advanced, since they are still under development and can make use of the latest technology for trusted products. Including products that are under evaluation benefits a program due to the volatile nature of security technology. On the other hand, there is also a greater risk in using a product that is undergoing evaluation. Such a product, being new, is less likely to have been tested in an operational environment. The product will not have as much, if any, field use from which to draw experience.
If the COTS product is not on the EPL, no security assurance documentation is likely to exist for the product. Therefore, any security documentation required for the product must be generated for the acquisition. Once again, depending on the detail of the documentation required, the cost of the development of this documentation may be prohibitive to the acquisition. This cost may include, for example, the procurement of a source code license for the product in order to have the data available to develop the security documentation. This prohibitive cost for source code licenses is especially true for closed proprietary systems. The cost may not be as prohibitive in an open systems environment, although developing documentation will always be substantially more expensive to the government than buying COTS documentation. Again, a cost-benefit analysis should be performed that includes the real requirements for detailed security documentation.
COTS product documentation can be a detailed description of the product. The DIDs for Commercial Off-the-Shelf (COTS) Manuals, DI-TMSS-80527, and Supplemental Data for Commercial Off-the-Shelf (COTS) Manuals, DI-TMSS-80528, should be addressed when requiring COTS documentation. Whatever method is used to request the COTS documentation, the documentation will be geared toward the generic design and use of the product. If the product must be modified or extended for a program, the COTS documentation for the product will not include these modifications and extensions, unless the modifications are performed by the vendor and the updated documentation is purchased during the acquisition.
The preparation of security documentation demands an engineering discipline be imposed on the development of the software. The use of a strict engineering discipline during development further contributes toward a more consistent implementation of the TCB. A result of this strict engineering discipline permeates the program, not just the TCB implementation.
The TCSEC describes the type of written evidence in the form of operational manuals and design and assurance documentation required for each class. During the procurement process, the required documentation must be explicitly defined. During the implementation process, this documentation must be developed, reviewed, and inspected to prove the ability of the security mechanisms to enforce the security policy. During the operational phase, the operational manuals for users and administrators are used to apply the provided security mechanisms. During any maintenance phase, the documentation is used to determine what effect a change may have on security. This evaluation must be accomplished prior to a change being performed. Finally, during the implementation, operational, and maintenance phases, configuration control verifies that only approved changes are included in the trusted product.
Security documentation is a subset of the software and hardware documentation required for a TCB. There are numerous documentation approaches and standards (e.g., MIL-STD-2167A) used today with their associated documentation requirements. The security documentation defined in this guideline is to be used in addition to the standard software and hardware documentation (e.g., Software Requirements Specifications, Software Design Documents, Interface Design Documents, or Software Test Plans). Security documentation is not a replacement for this standard documentation, nor is standard documentation a replacement for security documentation.
The security documentation defined in this guideline can fit very easily into the timeline defined by MIL-STD-2167A. Figure 1 illustrates the security documentation along with interdependencies and relative delivery schedules. The reviews on the timeline are the MIL-STD-2167A reviews. Each of the documents can be acquired, along with the standard software and hardware documentation, within the standard MIL-STD-2167A review cycle. Several iterations may be required before some security documents may be finalized. Additionally, although all of the lines in Figure 1 point downward, it may be necessary in any acquisition to change documents and models to reflect the actual implementation. As changes are made in a program for a multitude of reasons, the earlier documents may require revision. For simplification, no feedback mechanism is reflected in the figure.
Figure 2 relates the test documentation to other security documentation. The dotted box containing "Risk Assessment" indicates a process that is not performed by the developer/integrator team. The risk assessment process identifies some acquisition-specific security requirements that need to be included in the System Specification. Additionally, the risk assessment process enumerates the specific system vulnerabilities that are used to develop the Security Test Plan.
*Block 1-Sequence Number
*Block 2-Title or Description of Data
*Block 3 -Subtitle
*Block 4-Authority (Data Item (or DID) Number)
*Block 5-Contract Reference
*Block 6-Technical Office
*Block 7 -DD Form 250 Requirement
*Block 8-Approval (APP) Code
*Block 9 -Input to Integrating Associated Contractor (IAC)
*Block 10-Frequency
*Block 11-As of Date
*Block 12 -Date for First Submission
*Block 13-Date of Subsequent Submission/Event Identification
*Block 14-Distribution and Addressees
*Block 15-Total
*Block 16-Remarks
*Block 17-26 - Not Contractual Information
A few of these blocks are critical in amplifying the delivery requirements of data. Block 16 is the most critical in that it is used to tailor the requirements of the DID to best suit the specific acquisition. Blocks 10 through 13 are also critical in defining the delivery schedule for the data. The following subsections describe the general instructions and information needed to complete each block on the CDRL. Appendix A contains sample CDRLs for each TCSEC class, as appropriate. These sample CDRLs can be used for any acquisition by completing the blocks left blank and replacing the italicized information.
For the purposes of this guideline, the procurement instrument is the RFP and, specifically, the SOW (Section C of the RFP). The specific SOW paragraph (C.X, where X is a place holder which will have to be replaced with the appropriate number) should be cited in this block. (See Volume 2, pg. 11, of this Procurement Guideline series for more details.)
inspection and acceptance. The acceptance indicated in this block is not the same as the approval of a document indicated in block 8.
This block has been left blank in the sample CDRLs in Appendix A. However, in actual CDRLs, a blank in this block indicates that the inspection and acceptance location is specified in Block 16. If this is not true for the specific acquisition, the block should indicate the location for the inspection and acceptance.
This block has been left blank in the sample CDRLs in Appendix A. It is the responsibility of the procurement initiator to identify the appropriate information for this block in the specific acquisition.
This block is used if the government must provide input to a contractor so that the contractor can produce a document. For the data described in this guideline, this block will be left blank in most cases. This block is blank in the sample CDRLs in Appendix A.
A frequent error in the content of this block is "ASREQ" (As Required) without
amplification in Block 16. There is no way that a contractor can determine the cost of an "As Required" document during the proposal writing phase of a procurement. Therefore, in a proposal the contractor must assume "not required" for the frequency of delivery of documents with the "ASREQ" frequency. The result of this assumption is that the contractor will not include the cost of draft and final versions of a document in the price. Additionally, the government would not have the opportunity to conduct the draft and review cycle, which is beneficial to a complete document. The contractor may indicate that the draft and review cycle is to be done either as an option or through a task order, with the resulting additional cost to the contract. Therefore, it is always best to be explicit in stating the exact number of drafts that will be required for any data procured. This explicit definition does not belong in Block 10, but rather in Block 16.
This block has been left blank in the sample CDRLs in Appendix A. The milestones in Figure 1 should be used to constrain the data. Blocks 13 or 16 should be used for further explanation of the date in Block 11.
All of the sample CDRLs in Appendix A have "See Block 16" in Block 12 because the first submission of all security documentation is predicated on an event, or a review. The documentation shou