ISO/IEC TR 15443-2:2005

Information technology - Security techniques - A framework for IT security assurance - Part 2: Assurance methods

ISO/IEC TR 15443-2:2005 describes a variety of IT security assurance methods and approaches and relates them to the IT security assurance framework in ISO/IEC TR 15443-1. The emphasis is to identify qualitative properties of the assurance methods and elements that contribute to assurance, and where possible, to define assurance ratings. This material is intended for IT security professionals for the understanding of how to obtain assurance in a given life-cycle stage of a product or service. The objective is to describe and categorize assurance methods and approaches in a manner enabling a review of their comparable and synergetic properties. This will facilitate selection of the appropriate assurance method or and possible combination of assurance methods for a given IT security product, system, or service and its specific environment.

Technologies de l'information — Techniques de sécurité — Un canevas pour l'assurance de la sécurité dans les technologies de l'information — Partie 2: Méthodes d'assurance

General Information

• Status: Withdrawn
• Publication Date: 18-Sep-2005
• Withdrawal Date: 18-Sep-2005
• ICS: 35.030 - IT Security
• ICS: 35.040 - Information coding
• Technical Committee: ISO/IEC JTC 1/SC 27 - Information security, cybersecurity and privacy protection
• Drafting Committee: ISO/IEC JTC 1/SC 27/WG 3 - Security evaluation, testing and specification
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 16-Nov-2012
• Completion Date: 30-Oct-2025

Relations

• Revised: ISO/IEC TR 15443-2:2012 - Information technology - Security techniques - Security assurance framework - Part 2: Analysis
• Effective Date: 29-Jan-2011

Standards Content (Sample)

TECHNICAL ISO/IEC
REPORT TR
15443-2
First edition
2005-09-01
Information technology — Security
techniques — A framework for IT security
assurance —
Part 2:
Assurance methods
Technologies de l'information — Techniques de sécurité — Un canevas
pour l'assurance de la sécurité dans les technologies de l'information —
Partie 2: Méthodes d'assurance

Reference number
©
ISO/IEC 2005
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©  ISO/IEC 2005
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ii © ISO/IEC 2005 – All rights reserved

Contents Page
Foreword. v
Introduction . vi
1 Scope. 1
1.1 Purpose. 1
1.2 Field of Application. 1
1.3 Limitations. 2
2 Normative references. 2
3 Terms, definitions and abbreviated terms . 3
4 Overview and Presentation of Methods . 3
5 Assurance Life Cycle Phase and Legend . 4
5.1 Assurance Approach and Legend . 4
5.2 Actuality and Legend. 5
5.3 Security Relevance and Legend. 5
5.4 Overview Table. 5
5.5 Presentation Methodology. 7
6 Assurance Methods. 9
6.1 ISO/IEC 15408 – Evaluation criteria for IT security ±. 9
6.2 TCSEC – Trusted Computer System Evaluation Criteria ±. 10
6.3 ITSEC/ITSEM – Information Technology Security Evaluation Criteria and Methodology ± . 12
6.4 CTCPEC – Canadian Trusted Product Evaluation Criteria ± . 14
6.5 KISEC/KISEM – Korea Information Security Evaluation Criteria and Methodology ± . 15
6.6 RAMP – Rating Maintenance Phase ±. 17
6.7 ERM – Evaluation Rating Maintenance (in general) ± . 18
6.8 TTAP – Trust Technology Assessment Program ± . 20
6.9 TPEP – Trusted Product Evaluation Program ±. 21
6.10 Rational Unified Process® (RUP®) . 22
6.11 ISO/IEC 15288 – System Life Cycle Processes.24
6.12 ISO/IEC 12207 – Software Life Cycle Processes . 26
6.13 V–Model. 28
6.14 ISO/IEC 14598 – Software product evaluation . 30
6.15 X/Open Baseline Security Services±. 32
6.16 SCT – Strict Conformance Testing . 33
6.17 ISO/IEC 21827 – Systems Security Engineering – Capability Maturity Model
(SSE-CMM®) ± . 34
6.18 TCMM – Trusted Capability Maturity Model ± . 36
6.19 CMMI – Capability Maturity Model ® Integration .37
6.20 ISO/IEC 15504 – Software Process Assessment . 39
6.21 CMM – Capability Maturity Model® (for Software) . 40
6.22 SE-CMM® – Systems Engineering Capability Maturity Model ® . 42
6.23 TSDM – Trusted Software Development Methodology. 43
6.24 SdoC – Supplier’s declaration of Conformity . 45
6.25 SA-CMM® – Software Acquisition Capability Maturity Model®. 46
6.26 ISO 9000 Series – Quality Management . 47
6.27 ISO 13407 – Human Centered Design (HCD) . 48
6.28 Developer’s Pedigree (in general). 49
6.29 ISO/IEC 17025 – Accreditation Assurance . 50
6.30 ISO/IEC 13335 – Management of information and communications technology security
(MICTS) . 51
© ISO/IEC 2005 – All rights reserved iii

6.31 BS 7799-2 – Information security management systems – Specification with guidance for
use ±. 53
6.32 ISO/IEC 17799 – Code of practice for information security management ± . 54
6.33 FR – Flaw Remediation (in general) . 56
6.34 IT Baseline Protection Manual ± . 57
6.35 Penetration Testing ± . 58
6.36 Personnel Certification (in general) . 59
6.37 Personnel Certification (security related)±. 61
Bibliography . 63

iv © ISO/IEC 2005 – All rights reserved

Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
In exceptional circumstances, the joint technical committee may propose the publication of a Technical Report
of one of the following types:
— type 1, when the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts;
— type 2, when the subject is still under technical development or where for any other reason there is the
future but not immediate possibility of an agreement on an International Standard;
— type 3, when the joint technical committee has collected data of a different kind from that which is normally
published as an International Standard (“state of the art”, for example).
Technical Reports of types 1 and 2 are subject to review within three years of publication, to decide whether
they can be transformed into International Standards. Technical Reports of type 3 do not necessarily have to
be reviewed until the data they provide are considered to be no longer valid or useful.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC TR 15443-2, which is a Technical Report of type 3, was prepared by Joint Technical Committee
ISO/IEC JTC 1, Information technology, Subcommittee SC 27, IT Security techniques.
ISO/IEC TR 15443 consists of the following parts, under the general title Information technology — Security
techniques — A framework for IT security assurance:
⎯ Part 1: Overview and framework
⎯ Part 2: Assurance methods
The following part is under preparation:
⎯ Part 3: Analysis of assurance methods

© ISO/IEC 2005 – All rights reserved v

Introduction
The objective of this part of ISO/IEC TR 15443 is to describe a variety of assurance methods and approaches
that may be applicable to ICT security, as proposed or used by various types of organizations whether they
are generally acknowledged, de-facto approved or standardized, and to relate them to the assurance model of
ISO/IEC TR 15443-1. The emphasis is to identify qualitative properties of the assurance methods that
contribute to assurance, and where possible, to define assurance ratings. This material is catering to an ICT
Security professional for the understanding of how to obtain assurance in a given life cycle stage of product or
service.
This part of ISO/IEC TR 15443 gives for each item of the collection its aim, description and reference. Each
item of collection of assurance methods is then placed within the framework defined in ISO/IEC TR 15443-1.
The assurance methods listed in this part of ISO/IEC TR 15443 are considered to comprise generally known
items at the time of its writing. New methods may appear, and enhancements or other modification to the
existing ones may occur.
Developers, evaluators, quality managers and acquirers may select assurance methods from this part of
ISO/IEC TR 15443 for assurance of the ICT security software and systems; defining assurance requirements,
evaluating products, measuring security aspects and other purposes. In complement, they may also use
assurance methods which are not included here. This part of ISO/IEC TR 15443 is applicable to the
assurance of security aspects, although many of the methods may also be applicable for the assurance of
other critical aspects of software and systems.
This part of ISO/IEC TR 15443 is intended to be used together with ISO/IEC TR 15443-1.
This part of ISO/IEC TR 15443 will analyze assurance methods that may not be unique to ICT security;
however, guidance given in this part of ISO/IEC TR 15443 will be limited to ICT security requirements.
Similarly, additional terms and concepts defined in other International standardization initiatives (i.e. CASCO)
and International guides (e.g., ISO/IEC Guide 2) will be incorporated; however, guidance will be provided
specific to the field of ICT security and is not intended for general quality management and assessment, or
ICT conformity.
vi © ISO/IEC 2005 – All rights reserved

TECHNICAL REPORT ISO/IEC TR 15443-2:2005(E)

Information technology — Security techniques — A framework
for IT security assurance —
Part 2:
Assurance methods
1 Scope
1.1 Purpose
This part of ISO/IEC TR 15443 provides a collection of assurance methods including those not unique to ICT
security as long as they contribute to overall ICT security. It gives an overview as to their aim and describes
their features, reference and standardization aspects.
In principle, the resultant ICT security assurance is the assurance of the product, system or service in
operation. The resultant assurance is therefore the sum of the assurance increments obtained by each of the
assurance methods applied to the product, system or service during its life cycle stages. The large number of
available assurance methods makes guidance necessary as to which method to apply to a given ICT field to
gain recognized assurance.
Each item of the collection presented in this part of ISO/IEC TR 15443 is classified in an overview fashion
using the basic assurance concepts and terms developed in ISO/IEC TR 15443-1.
Using this categorization, this part of ISO/IEC TR 15443 guides the ICT professional in the selection, and
possible combination, of the assurance method(s) suitable for a given ICT security product, system, or service
and its specific environment.
1.2 Field of Application
This part of ISO/IEC TR 15443 gives guidance in a summary and overview fashion. It is suitable to obtain from
the presented collection a reduced set of applicable methods to choose from, by way of exclusion of
inappropriate methods.
The summaries are informative to provide the basics to facilitate the understanding of the analysis without
requiring the source standards.
Intended users of this part of ISO/IEC TR 15443 include the following:
1. acquirer (an individual or organization that acquires or procures a system, software product or software
service from a supplier);
2. evaluator (an individual or organization that performs an evaluation; an evaluator may, for example, be a
testing laboratory, the quality department of a software development organization, a government
organization or a user);
3. developer (an individual or organization that performs development activities, including requirements
analysis, design, and testing through acceptance during the software life cycle process);
© ISO/IEC 2005 – All rights reserved 1

4. maintainer (an individual or organization that performs maintenance activities);
5. supplier (an individual or organization that enters into a contract with the acquirer for the supply of a
system, software product or software service under the terms of the contract) when validating software
quality at qualification test;
6. user (an individual or organization that uses the software product to perform a specific function) when
evaluating quality of software product at acceptance test;
7. security officer or department (an individual or organization that perform a systematic examination of the
software product or software services) when evaluating software quality at qualification test.
1.3 Limitations
This part of ISO/IEC TR 15443 gives guidance in an overview fashion only. ISO/IEC TR 15443-3 provides
guidance to refine this choice for better resolution of assurance requirements enabling a review of their
comparable and synergetic properties.
The regulatory infrastructure to support verification of an assurance approach and the personnel to perform
verification is outside the scope of this part of ISO/IEC TR 15443.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 9000, Quality management systems — Fundamentals and vocabulary
ISO 9001, Quality management systems — Requirements
ISO/IEC 9126-1, Software engineering — Product quality — Part 1: Quality model
ISO/IEC 12207, Information technology — Software life cycle processes
ISO/IEC 13335-1, Information technology — Security techniques — Management of information and
communications technology security — Part 1: Concepts and models for information and communications
technology security management
ISO/IEC TR 13335-2, Information technology — Guidelines for the management of IT Security — Part 2:
Managing and planning IT Security
ISO/IEC TR 13335-3, Information technology — Guidelines for the management of IT Security — Part 3:
Techniques for the management of IT Security
ISO/IEC TR 13335-4, Information technology — Guidelines for the management of IT Security — Part 4:
Selection of safeguards
ISO/IEC TR 13335-5, Information technology — Guidelines for the management of IT Security — Part 5:
Management guidance on network security
ISO/IEC 14598-1, Information technology — Software product evaluation — Part 1: General overview
ISO/IEC 15939, Software engineering — Software measurement process
ISO/IEC 15288, Systems engineering — System life cycle processes
2 © ISO/IEC 2005 – All rights reserved

ISO/IEC 15408-1, Information technology —Security techniques — Evaluation criteria for IT security — Part 1:
Introduction and general model
ISO/IEC 15408-2, Information technology — Security techniques — Evaluation criteria for IT security — Part 2:
Security functional requirements
ISO/IEC 15408-3, Information technology — Security techniques — Evaluation criteria for IT security — Part 3:
Security assurance requirements
ISO/IEC 15504-1, Information technology — Process assessment — Part 1: Concepts and vocabulary
ISO/IEC 15504-2, Information technology — Process assessment — Part 2: Performing and assessment
ISO/IEC 15504-3, Information technology — Process assessment — Part 3: Guidance on performing an
assessment
ISO/IEC 15504-4, Information technology — Process assessment — Part 4: Guidance on use for process
improvement and process capability determination
ISO/IEC TR 15504-5, Information technology — Software Process Assessment — Part 5: An assessment
model and indicator guidance
ISO/IEC 17799, Information technology — Security techniques — Code of practice for information security
management
ISO/IEC 21827, Information technology — Systems Security Engineering — Capability Maturity Model
(SSE-CMM®)
ISO/IEC 90003, Software engineering — Guidelines for the application of ISO 9001:2000 to computer
software
3 Terms, definitions and abbreviated terms
For the purposes of this document, the terms, definitions and abbreviated terms given in ISO/IEC TR 15443-1
apply.
4 Overview and Presentation of Methods
Part 1 of this technical report provides a framework for the categorization of existing assurance methods. This
clause lists and presents the available assurance methods that are of interest and directly related to the field
of ICT security. It classifies these methods according to the framework:
⎯ according to the different assurance phases - describing its lifecycle aspect: Design, Implementation,
Integration, Verification, Deployment, Transition, or Operation;
⎯ according to the different assurance approach: Product, Process or Environment.
As stated in Part 1 of this technical report an assurance method may comprise a combination of assurance
approach and assurance phase.
For additional user guidance the overview table in sub-clause 5.4 presents this categorization along with a
mention of:
⎯ the ICT security relevance of the individual methods and
⎯ the actuality of the individual methods.
© ISO/IEC 2005 – All rights reserved 3

5 Assurance Life Cycle Phase and Legend
The overview table in sub-clause 5.4 lists the later presented methods classified according to their Life Cycle
Phase. The subclause title of each individual listing repeats this classification.
The different Life Cycle Phases of interest are graphically represented by four columns of the table. For this
purpose and approaching the concepts of ISO/IEC 15288 and ISO 9000, the Technical Life Cycle Processes
are grouped into four stages, one for each column and abbreviated by one letter as follows:
D Design, including the processes Stakeholder Requirements Definition, Requirements Analysis,
Architectural Design and Implementation
I Integration, including the processes Integration and Verification
T Transition, including the processes Replication, Transition, Deployment and Validation
O Operation, including the processes Operation, Maintenance and Disposal
Note 1: A given assurance method may cover one life cycle phase only remotely. In this case, this phase is not
flagged in the graphical presentation.
Note 2: The life cycle processes D-I-T-O are those applicable to a specific ICT system and its components, i.e.,
hardware, software. The development and improvement of the life cycle processes are a second dimension which may be
graphically represented but presently is not shown. In ICT security this dimension is particularly important for the security
management methods applied to ICT systems in the operations phase, such as ISO/IEC 17799 and BS 7799-2. This
second dimension essentially comprises process assessment and documentation, development, measurement,
improvement and certification. This second dimension is orthogonal to the D-I-T-O dimension.
5.1 Assurance Approach and Legend
The overview table in sub-clause 5.4 lists the later presented methods categorized according to their
assurance approach. The subclause title of each individual listing repeats this categorization.
The respective assurance approach categories of the methods are represented symbolically (refer to Table 1):
— Product Assurance: showing the life cycle phase letter within arrows, in a blank " field, e.g. ⇒D⇒
— Process Assurance: showing the life cycle phase letter white on shaded background, e.g., D
— Environmental assurance: showing the life cycle phase cell as with side bars left and right, e.g.  D .
Table 1 — Assurance methods in the framework - Legend
Clause
Design/
Assurance --Phase→
Integration/ Deployment
Implemen- Operation
Verification /Transition
--Approach↓
tation
Product[/System/Service] [±] ⇒D⇒ ⇒I⇒ ⇒T⇒ ⇒O⇒
Process [±] D I T O
Environment D I T O
[/Organization/Personnel] [±]
Note 1: As methods may feature a combination of approaches, the symbols may be cumulated; e.g., a method
offering both process and environmental assurance will be the letter on a dark field with a dark frame.
Note 2: A given assurance method may cover one approach more or less extensively. This visual overview
presentation is not suited to represent the extent of coverage of the various assurance approaches by a given method.
4 © ISO/IEC 2005 – All rights reserved

Note 3: A given assurance method may cover one approach only remotely. In this case, this approach is not flagged in
the graphical presentation.
5.2 Actuality and Legend
As of the great number of methods the user of This part of ISO/IEC TR 15443 is given some direction as to
their status. The overview table in sub-clause 5.4 reflects this status as follows:
— the methods presently in relatively wide-spread use and active maintenance are represented in the
overview table of sub-clause 5.4 in bold characters.
— the methods becoming obsolete, superseded, merged or otherwise loosing actuality are represented in
the overview table of sub-clause 5.4 in regular slim characters.
Note: This legend is not repeated in the subclause title of the individual listing.
5.3 Security Relevance and Legend
As of the great number of methods the user of This part of ISO/IEC TR 15443 is given some direction as to
their ICT security relevance. The overview table in sub-clause 5.4 and the applicable subclause title reflect
this status as follows:
— Methods which are specifically oriented towards ICT security have been awarded a "lock" sign (±).
5.4 Overview Table
Table 2 presents an overview of the considered assurance methods, together with their classification
according to the framework developed in Part 1 of this Technical Report, as explained above.
© ISO/IEC 2005 – All rights reserved 5

Table 2 — Assurance methods in the framework - Overview
Clause
Assurance --Phase→
Design/
Integration/ Deployment/
Operation
Implemen-
Verification Transition
--Approach↓
tation
6.1 ISO/IEC 15408 – Evaluation criteria
⇒D⇒ ⇒I⇒ ⇒T⇒ ⇒O⇒
for IT security ±
6.2 TCSEC – Trusted Computer System
⇒D⇒ ⇒I⇒ ⇒O⇒
Evaluation Criteria ±
6.3 ITSEC/ITSEM – Information
Technology Security Evaluation Criteria ⇒D⇒ ⇒I⇒ ⇒O⇒
and Methodology ±
6.4 CTCPEC – Canadian Trusted Product
⇒D⇒ ⇒I⇒
Evaluation Criteria ±
6.5 KISEC/KISEM – Korea Information
⇒D⇒ ⇒I⇒ ⇒O⇒
Security Evaluation Criteria and
Methodology ±
6.6 RAMP – Rating Maintenance
⇒D⇒ ⇒I⇒ ⇒O⇒
Phase ±
6.7 ERM – Evaluation Rating
⇒D⇒ ⇒I⇒ ⇒O⇒
Maintenance (in general) ±
6.8 TTAP – Trust Technology
⇒D⇒ ⇒I⇒
Assessment Program ±
6.9 TPEP – Trusted Product Evaluation
⇒D⇒ ⇒I⇒
Program ±
6.10 Rational Unified Process® (RUP®) ⇒D⇒ ⇒I⇒ ⇒T⇒
6.11 ISO/IEC 15288 – System Life Cycle
⇒D⇒ ⇒I⇒ ⇒T⇒ ⇒O⇒
Processes
6.12 ISO/IEC 12207 – Software Life Cycle
⇒D⇒ ⇒I⇒ ⇒T⇒ ⇒O⇒
Processes
6.13 V–Model ⇒D⇒ ⇒I⇒ ⇒T⇒ ⇒O⇒
6.14 ISO/IEC 14598 – Software product
⇒D⇒  ⇒O⇒
evaluation
6.15 X/Open Baseline Security Services± ⇒D⇒
6.16 SCT – Strict Conformance Testing ⇒I⇒
6.17 ISO/IEC 21827 – Systems Security
Engineering – Capability Maturity D I T O
Model (SSE-CMM®) ±
6.18 TCMM – Trusted Capability Maturity
D I
Model ±
6.19 CMMI – Capability Maturity Model ®
D I T O
Integration
6.20 ISO/IEC 15504 – Software Process
D I T O
Assessment
6.21 CMM – Capability Maturity Model®
D I
(for Software)
6 © ISO/IEC 2005 – All rights reserved

Table 2 (continued)
Design/
Assurance --Phase→
Integration/ Deployment/
Clause Operation
Implemen-
Verification Transition
--Approach↓
tation
6.22 SE-CMM® – Systems Engineering
D I
Capability Maturity Model ®
6.23 TSDM – Trusted Software
D I
Development Methodology
6.24 SdoC – Supplier’s declaration of
D
Conformity
6.25 SA-CMM® – Software Acquisition
T
Capability Maturity Model®
6.26 ISO 9000 Series – Quality
D I T O
Management
6.27 ISO 13407 – Human Centered Design
D
(HCD)
6.28 Developer’s Pedigree (in general) D
6.29 ISO/IEC 17025 – Accreditation
D I
Assurance
6.30 ISO/IEC TR 13335 – Guidelines for
the management of IT Security I T O
(GMITS) ±
6.31 BS 7799-2 – Information security
management systems – Specification
O
with guidance
for use ±
6.32 ISO/IEC 17799 – Code of practice for
O
information security management ±
6.33 FR – Flaw Remediation (in general)  O
6.34 IT Baseline Protection Manual ±  ⇒O⇒
6.35 Penetration Testing ±  ⇒O⇒
6.36 Personnel Certification (non security
O
related)
6.37 Personnel Certification (security
D I T O
related)±
5.5 Presentation Methodology
Clause 6 is intended to provide a review of identified assurance methods. Because many assurance methods
contribute to different assurance approaches and assurance, each assurance method shall be presented here
with its own way of description and views. No comparing is provided at this stage.
In the subclauses Clause 6 there will be a structured synopsis for each assurance method identified in this
technical framework.
© ISO/IEC 2005 – All rights reserved 7

The title of the method is the a self explanatory name, if possible the full and official name of the assurance
method for proper reference, as well as a Mnemonic for its reference when appropriate.
Each synopsis is broken down into:
• Aim: Brief characteristic purpose of the method.
• Description: Short description of the method.
• Sources: Address/Reference to committees and/or organizations involved, documents the
describing method and/or standardisation thereof.
8 © ISO/IEC 2005 – All rights reserved

6 Assurance Methods
6.1 ISO/IEC 15408 – Evaluation criteria for IT security ±
⇒D⇒ ⇒I⇒ ⇒T⇒ ⇒O⇒
6.1.1 Aim
To provide a harmonized framework and detailed evaluation criteria for ICT security evaluation, suitable for
both government and general use.
6.1.2 Description
The Common Criteria were developed on behalf of a number of governmental information security agencies
as a way of independently assessing the security characteristics of ICT products and systems. The criteria
were developed in conjunction with JTC 1 Subcommittee 27, Security Techniques, and published as
International Standard ISO/IEC 15408.
The Common Criteria separate consideration of security functionality from security assurance and specify
detailed techniques and functions that can aid in the development of confidence that a security product or
system meets its security objectives. The specific assurance techniques and functions are defined in
ISO/IEC 15408-3, and are primarily, but not exclusively, aimed towards assurance obtained through
independent assessment or verification. It is intended that consistent application of the evaluation criteria can
be verified through national certification schemes.
Within ISO/IEC 15408-3, assurance techniques are divided into different areas of applicability, called classes.
Within each class, different techniques are identified, called families. Each family then identifies one or more
levels of rigor by which the technique can be applied; these are called components. Each component specifies
the precise actions and evidence elements required.
A number of packages of assurance components that work together in a complementary manner are defined
within ISO/IEC 15408-3. These are called Evaluation Assurance Levels (Earls).
A supporting methodology for application of these criteria, the Common Evaluation Methodology, is being
developed by the Common Evaluation Methodology Working Group, part of the Common Criteria project.
6.1.3 Sources
Refer to Clause 2: ISO/IEC 15408-1, ; ISO/IEC 15408-2, ; ISO/IEC 15408-3,
Note: ISO/IEC 15408 is a product of the committee:
ISO/IEC JTC 1/SC 27/WG 3 Information technology - Security techniques - Security evaluation criteria
© ISO/IEC 2005 – All rights reserved 9

6.2 TCSEC – Trusted Computer System Evaluation Criteria ±
⇒D⇒ ⇒I⇒ ⇒O⇒
6.2.1 Aim
To grade or rate the security offered by a computer system product.
6.2.2 Description
The Trusted Computer System Evaluation Criteria (TCSEC) is a collection of criteria that was previously used
to grade or rate the security offered by a computer system product. No new evaluations are being conducted
using the TCSEC although there are some still ongoing at this time. The TCSEC is sometimes referred to as
"the Orange Book" because of its orange cover.
A product is "compliant" with the TCSEC if it has been evaluated by the Trusted Product Evaluation Program
(TPEP) or Trust Technology Assessment Program (TTAP) to comply with the requirements of a rated class of
TCSEC and if an independent assessment showed the product to have the features and assurances of that
class.
A class is the specific collection of requirements in the Trusted Computer System Evaluation Criteria (TCSEC)
to which an evaluated system conforms. There are seven classes in the TCSEC A1, B3, B2, B1, C2, C1, and
D, in decreasing order of features and assurances. Thus, a system evaluated at class B3 has more security
features and/or a higher confidence that the security features work as intended than a system evaluated at
class B1. The requirements for a higher class are always a superset of the lower class. Thus a B2 system
meets every C2 functional requirement and has a higher level of assurance.
A division is a set of classes (see Question 11) from the Trusted Computer System Evaluation Criteria
(TCSEC) (see TCSEC Criteria Concepts FAQ, Question 1). There are 4 divisions A, B, C, and D in decreasing
order of assurance and features. Thus, a system evaluated at a class in division B has more security features
and/or a higher confidence that the features work as intended than a system evaluated at a class in division C.
Although the Computer Security Subsystem Interpretation (CSSI) of the TCSEC specifies criteria for various D
ratings, these are not reflected in the TCSEC itself, which has no requirements for D division systems. An
unrated system is, by default, division D.
The Requirements for the different classes are:
Class D: Minimal Protection - is reserved for those systems that have been evaluated but that fail to meet
the requirements for a higher evaluation class.
Class 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 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 of
sensitivity.
Class 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.
Class 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 labeling (e.g., secret or
proprietary), and mandatory access control over named subjects and objects must be present.
The capability must exist for accurately labeling exported information.
10 © ISO/IEC 2005 – All rights reserved

Class B2: Structured Protection - In clas 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
automated data processing 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.
Class B3: Security Domains - The clas 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.
Class A1: Verified Design - Systems in clas 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. An FTLS is a top level specification of the
system written in a formal mathematical language to allow theorems (showing the
correspondence of the system specification to its formal requirements) to be hypothesized and
formally proven. In keeping with the extensive design and development analysis of the TCB
required of systems in class A1, more stringent configuration management is required and
procedures are established for securely distributing the system to sites. A system security
administrator is supported.
6.2.3 Sources
Refer to Bibliography [45] Trusted Computer System Evaluation Criteria (TCSEC), 1985.
Note: The TCSEC, its interpretations, and guidelines all have different color covers and are sometimes known as the
"Rainbow Series". The TCSEC is a standard internal to and product of:
Department of Defense, Washington, D.C., USA.
© ISO/IEC 2005 – All rights reserved 11

6.3 ITSEC/ITSEM – Information Technology Security Evaluation Criteria
and Methodology ±
⇒D⇒ ⇒I⇒ ⇒O⇒
6.3.1 Aim
To provide a framework of evaluation criteria and evaluation methodology for IT security evaluation for the
European market.
6.3.2 Description
The evaluation criteria ”Information Technology Security Evaluation Criteria (ITSEC)” and the evaluation
manual ”Information Technology Security Evaluation Manual (ITSEM)” are among the predecessor documents
of the Common Criteria and of the Common Evaluation Methodology. They have been developed in the early
1990s by the four European nations France, Germany, the Netherlands and the United Kingdom.
The ITSEC assurance is based on the approach introduced in the TCSEC. However, the separation between
functional and assurance requirements in the ITSEC allows a greater flexibility. The assurance requirements
are themselves again split into the two aspects of effectiveness and correctness. Assessment of effectiveness
involves consideration of the following aspects of the Target of Evaluation (TOE):
⎯ the suitability of the Toe's security enforcing functions to counter the threats to the security of the TOE
identified in the security target;
⎯ the ability of the Toe's security enforcing functions and mechanisms to bind together in a way that is
mutually supportive and provides an integrated and effective whole
⎯ the ability of the Toe's security mechanisms to withstand direct attack;
⎯ whether known security vulnerabilities in the construction of the TOE could in practice compromise the
security of the TOE;
⎯ that the TOE cannot be configured or used in a manner which is insecure but which an administrator or
end-user of the TOE would reasonably believe to be secure;
⎯ whether known security vulnerabilities in the operation of the TOE could in practice compromise the
security of the TOE.
The focus of the assurance effectiveness requirements is more on those aspects where the evaluator has to
use the own knowledge and experience to assess whether the security approach in the evaluated IT product
or system is reasonable.
The focus of the assurance correctness requirements in the ITSEC is more on the aspects which shall confirm
that the developer information concerning the IT security of the evaluated product or system is correct.
The ITSEC distinguishes between correctness requirements for the construction and the operation of the TOE.
The construction criteria cover the Development Process with different specification layers beginning with a
high level description of the requirements which can be instantiated to an Architectural Design which can
again be instantiated to a Detailed Design and to the implementation representation. Construction aspects of
the Development Environment covered by the ITSEC are Configuration Control, Programming Languages and
Compilers, and Developers Security.
The operation requirements are further subdivided into the aspects of Operational Documentation with User
Documentation and Administration Documentation and the Operational Environment with Delivery and
Configuration, and Start-up and Operation.
12 © ISO/IEC 2005 – All rights reserved

The correctness requirements in the ITSEC are presented in the form of six hierarchically ordered assurance
levels E1 to E6. From level to level additional requirements ensure a more
...