ETSI TS 102 165-1 V5.2.3 (2017-10)

CYBER; Methods and protocols; Part 1: Method and pro forma for Threat, Vulnerability, Risk Analysis (TVRA)

RTS/CYBER-0018

General Information

• Status: Published
• Publication Date: 16-Oct-2017
• Technical Committee: CYBER - Cyber Security
• Current Stage: 12 - Completion
• Due Date: 16-Oct-2017
• Completion Date: 17-Oct-2017

Standards Content (Sample)

TECHNICAL SPECIFICATION
CYBER;
Methods and protocols;
Part 1: Method and pro forma for Threat,
Vulnerability, Risk Analysis (TVRA)

�
2 ETSI TS 102 165-1 V5.2.3 (2017-10)

Reference
RTS/CYBER-0018
Keywords
authentication, confidentiality, security

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3 ETSI TS 102 165-1 V5.2.3 (2017-10)
Contents
Intellectual Property Rights . 6
Foreword . 6
Modal verbs terminology . 6
Introduction . 6
1 Scope . 8
2 References . 8
2.1 Normative references . 8
2.2 Informative references . 8
3 Definitions, symbols and abbreviations . 10
3.1 Definitions . 10
3.2 Symbols . 11
3.3 Abbreviations . 12
4 Introduction . 13
4.1 Role of TVRA . 13
4.2 Generic TVRA relationships . 16
4.3 Countermeasure strategies . 18
4.3.0 Overview of strategies . 18
4.3.1 Asset redesign . 18
4.3.2 Asset hardening . 18
4.4 Relationship with Common Criteria evaluation . 18
5 TVRA method . 19
5.1 Overview . 19
5.1.0 Introduction. 19
5.1.1 Target of Evaluation description . 21
5.1.1.0 Introduction . 21
5.1.1.1 Security environment . 21
5.1.1.2 Security objectives . 22
5.1.1.3 Security requirements. 23
5.1.1.3.1 The relationship between security objectives and security requirements . 23
5.1.1.3.2 Security requirements statements . 23
5.1.1.3.3 Interaction with ISO/IEC 15408 . 24
5.1.2 Threats and threat agents . 25
5.2 Actors and roles . 27
5.3 Rationale. 27
6 Method process . 27
6.1 Overview . 27
6.2 Step 1: Identification of Target Of Evaluation (TOE) . 28
6.3 Step 2: Identification of objectives . 29
6.4 Step 3: Identification of functional security requirements . 29
6.5 Step 4: Systematic inventory of the assets . 30
6.6 Step 5: Systematic identification of vulnerabilities and threat level . 32
6.6.0 Overview . 32
6.6.1 Identification of weakness . 32
6.6.2 Identification of a vulnerability . 32
6.6.3 Identification of attack method . 32
6.6.3.0 Introduction . 32
6.6.3.1 Assessment of the practicality . 32
6.6.3.1.0 Core assessment. 32
6.6.3.1.1 Knowledge factor . 33
6.6.3.1.2 Time factor . 33
6.6.3.1.3 Expertise factor . 34
6.6.3.1.4 Opportunity factor . 34
6.6.3.1.5 Equipment factor . 35
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4 ETSI TS 102 165-1 V5.2.3 (2017-10)
6.6.3.1.6 Intensity factor . 35
6.7 Step 6: Calculation of the likelihood of the attack and its impact . 37
6.8 Step 7: Establishment of the risks . 38
6.8.0 Overview . 38
6.8.1 Impact of intensity . 38
6.8.2 Classification of risk . 38
6.8.2.1 Overview . 38
6.9 Step 8: Security countermeasure identification . 39
6.9.0 Introduction. 39
6.9.1 Countermeasures in the system . 40
6.9.2 Composite countermeasures applied to the system . 40
6.9.3 Impact of composite countermeasures applied to the system . 40
6.10 Step 9: Countermeasure Cost-benefit analysis . 41
6.10.0 Introduction. 41
6.10.1 Standards design . 41
6.10.2 Implementation . 41
6.10.3 Operation . 41
6.10.4 Regulatory impact . 42
6.10.5 Market acceptance . 42
6.11 Step 10: Specification of detailed requirements . 42
Annex A (normative): TVRA pro forma . 43
Annex B (informative): The role of motivation . 44
Annex C: Void . 45
Annex D (informative): Denial of service attacks . 46
D.0 Introduction . 46
D.1 Void . 46
D.2 DDoS characteristics . 46
D.2.1 Introduction . 46
D.2.2 L2 DDoS attacks . 47
D.2.3 L3 DDoS attacks . 47
D.2.4 L4 DDoS attacks . 47
D.2.5 L7 DDoS attacks . 48
D.2a Difficulties of defence . 48
D.3 Defence against DDoS . 48
D.3.0 Overview . 48
D.3.1 Preventive Mechanisms . 49
D.3.1.0 Introduction. 49
D.3.1.1 Firewalling . 49
D.3.1.2 TCP anti-spoofing . 49
D.3.1.3 Traffic shaping . 49
D.3.1.4 Border Session Manager . 49
D.3.1.5 GeoIP blocking . 49
D.3.2 Reactive Mechanisms . 49
D.3.2.0 Introduction. 49
D.3.2.1 Signature detection mechanisms . 49
D.3.2.2 Anomaly detection mechanisms . 50
D.3.3 Void . 50
D.3.4 Information sharing schemes for prevention and reaction . 50
Annex E (informative): TVRA database structure . 51
E.1 Database structure . 51
E.2 SQL code for TVRA database . 53
E.2.0 Introduction . 53
E.2.1 Lookup tables . 53
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5 ETSI TS 102 165-1 V5.2.3 (2017-10)
E.2.1a Lookup table initialization . 55
E.2.2 Core tables . 57
E.2.3 Linking tables . 58
E.2.4 Void . 59
Annex F: Void . 60
Annex G (informative): TVRA Risk Calculation Template and Tool . 61
Annex H (informative): TVRA Countermeasure Cost-Benefit Analysis Template and Tool . 62
Annex I (informative): Bibliography . 64
I.1 UML . 64
I.2 Others . 64
Annex J (informative): Change history . 65
History . 66

ETSI
6 ETSI TS 102 165-1 V5.2.3 (2017-10)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (https://ipr.etsi.org/).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Trademarks
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ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
Foreword
This Technical Specification (TS) has been produced by ETSI Technical Committee Cyber Security (CYBER).
The present document is part 1 of a multi-part deliverable covering methods and protocols for security standardization,
as identified below:
Part 1: "Method and pro forma for Threat, Vulnerability, Risk Analysis (TVRA)";
Part 2: "Protocol Framework Definition; Security Counter Measures".
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
The present document is one of a set of documents that addresses standardization of security protocols and mechanisms
within the context of the eEurope 2005 programme and which, within ETSI, has been considered as a tool in the
"Design for Assurance" approach to achieving security in ICT systems. The suite of documents is composed as follows:
• ETSI EG 202 387 [i.1]: "Telecommunications and Internet converged Services and Protocols for Advanced
Networking (TISPAN); Security Design Guide; Method for application of Common Criteria to ETSI
deliverables".
• ETSI ES 202 383 [i.23]: "Telecommunications and Internet converged Services and Protocols for Advanced
Networking (TISPAN); Security Design Guide; Method and proforma for defining Security Targets".
• ETSI ES 202 382 [i.24]: "Telecommunications and Internet converged Services and Protocols for Advanced
Networking (TISPAN); Security Design Guide; Method and proforma for defining Protection Profiles".
• ETSI TS 102 165-1: "CYBER; Methods and protocols; Method and pro forma for Threat,
Vulnerability, Risk Analysis (TVRA)" (the present document).
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7 ETSI TS 102 165-1 V5.2.3 (2017-10)
• ETSI TS 102 165-2 [i.25]: "CYBER; Methods and protocols; Protocol Framework Definition; Security
Counter Measures".
• ETSI TS 102 556 [i.5]: "Telecommunication and Internet converged Services and Protocols for Advanced
Networking (TISPAN); Protection Profile".
• ETSI EG 202 549 [i.6]: "Telecommunication and Internet converged Services and Protocols for Advanced
Networking (TISPAN); Design Guide; Application of security countermeasures to service capabilities".
These documents are developed based on the objectives of the eEurope programme and are also developed to ensure
they comply with the overall objectives of the European regulatory framework as defined in the following documents:
• Directive 2002/19/EC [i.16] of the European Parliament and of the council of 7 March 2002 on access to, and
interconnection of, electronic communications networks and associated facilities (Access Directive).
• Directive 2002/20/EC [i.17] of the European Parliament and of the council of 7 March 2002 on the
authorization of electronic communications networks and services (Authorization Directive).
• Directive 2002/21/EC [i.18] of the European Parliament and of the council of 7 March 2002 on a common
regulatory framework for electronic communications networks and services (Framework Directive).
• Directive 2002/22/EC [i.19] of the European Parliament and of the council of 7 March 2002 on universal
service and users' rights relating to electronic communications networks and services (Universal Service
Directive).
• Directive 2002/58/EC [i.20] of the European Parliament and of the council of 12 July 2002 concerning the
processing of personal data and the protection of privacy in the electronic communications sector (Directive on
privacy and electronic communications).
The eEurope 2005 action plan has been drawn up to focus on "the widespread availability and use of broadband
networks throughout the Union … and the security of networks and information, eGovernment, eHealth and eBusiness"
requiring a supporting infrastructure, which is truly pan-European. To quote COM(2002)263 [i.8]: "By 2005 Europe
should have … a secure information infrastructure".
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8 ETSI TS 102 165-1 V5.2.3 (2017-10)
1 Scope
The present document defines a method primarily for use by ETSI standards developers in undertaking an analysis of
the threats, risks and vulnerabilities of an Information and Communications Technology (ICT) system.
NOTE: The method described has been tailored to apply to pre-production but can be applied to production
devices with due attention given to possibility that the application of countermeasures may be
unachievable for a re-design strategy.
The method described in the present document builds from the Common Criteria for security assurance and evaluation
defined in ISO/IEC 15408 [i.27], [i.28], [i.29] and specifically targets the means to build a Threat Vulnerability and
Risk Analysis (TVRA) to allow its reference by an ETSI specification developed using the guidelines given in ETSI
EG 202 387 [i.1] and ETSI ES 202 382 [i.24]. The TVRA forms part of the documentation set for the Target Of
Evaluation as specified in ETSI ES 202 382 [i.24] with its intended audience being a developer of standards based
Protection Profiles.
The use of the method described in the present document for application outside the "Design for Assurance" paradigm
described in ETSI EG 202 387 [i.1] is supported but some of the examples and stages of evaluation may not be
appropriate.
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
https://docbox.etsi.org/Reference/.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI EG 202 387: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Security Design Guide; Method for application of Common
Criteria to ETSI deliverables".
[i.2] ETSI TR 187 011: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); NGN Security; Application of ISO-15408-2 requirements to
ETSI standards - guide, method and application with examples".
[i.3] ETSI TR 187 002: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); TISPAN NGN Security (NGN-SEC); Threat, Vulnerability and
Risk Analysis".
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9 ETSI TS 102 165-1 V5.2.3 (2017-10)
[i.4] ETSI TR 102 055: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); ENUM scenarios for user and infrastructure ENUM".
[i.5] ETSI TS 102 556: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Protection Profile".
[i.6] ETSI EG 202 549: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Design Guide; Application of security countermeasures to
service capabilities".
[i.7] ETSI TS 102 051: "ENUM Administration in Europe".
[i.8] COM(2002)263: "Communication from the Commission to the Council, the European Parliament,
the Economic and Social Committee and the Committee of the regions".
NOTE: Available at http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=COM:2002:0263:FIN:EN:PDF.
[i.9] ETSI ETR 332 (1996): "Security Techniques Advisory Group (STAG); Security requirements
capture".
[i.10] CESG: "HMG IA Standard Numbers 1 & 2 - Supplement - Technical Risk Assessment and Risk
Treatment", Issue No: 1.0, April 2012.
NOTE: The document is no longer supported by CESG and has been replaced with new guidance. See for more
information: https://www.cesg.gov.uk/articles/outcomes-over-process-how-risk-management-changing-
government.
The document is still available at:
https://www.ncsc.gov.uk/content/files/guidance_files/IS1%20%26%202%20Supplement%20-
%20Technical%20Risk%20Assessment%20and%20Risk%20Treatment%20-
%20issue%201.0%20April%202012%20-%20NCSC%20Web.pdf, and is available for use under the
Open Government Licence: http://www.nationalarchives.gov.uk/doc/open-government-
licence/version/1/open-government-licence.htm.
[i.11] CC Users Forum (September 2014): "Collaborative Protection Profiles: The Benefits of an
Evolved Common Criteria Implementation".
NOTE: Available from http://www.ccusersforum.org/library/wp/cPP_White_Paper.pdf.
[i.12] ISO/IEC 27002:2005: "Information technology -- Security techniques -- Code of practice for
information security management".
[i.13] ISO/IEC 27001:2005: "Information Technology - Security Techniques - Information Security
Management Systems - Requirements".
[i.14] ptc/04-10-02: "Object Management Group. UML 2.0 Superstructure Specification", edition, 2004.
[i.15] IETF RFC 3761: "The E.164 to Uniform Resource Identifiers (URI) Dynamic Delegation
Discovery System (DDDS) Application (ENUM)".
[i.16] Directive 2002/19/EC of the European Parliament and of the Council of 7 March 2002 on access
to, and interconnection of, electronic communications networks and associated facilities (Access
Directive).
[i.17] Directive 2002/20/EC of the European Parliament and of the Council of 7 March 2002 on the
authorization of electronic communications networks and services (Authorization Directive).
[i.18] Directive 2002/21/EC of the European Parliament and of the Council of 7 March 2002 on a
common regulatory framework for electronic communications networks and services (Framework
Directive).
[i.19] Directive 2002/22/EC of the European Parliament and of the Council of 7 March 2002 on
universal service and users' rights relating to electronic communications networks and services
(Universal Service Directive).
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10 ETSI TS 102 165-1 V5.2.3 (2017-10)
[i.20] Directive 2002/58/EC of the European Parliament and of the Council of 12 July 2002 concerning
the processing of personal data and the protection of privacy in the electronic communications
sector (Directive on privacy and electronic communications).
[i.21] ISO 31000:2009: "Risk management - Principles and guidelines".
NOTE: The above reference supersedes the reference to AS/NZS 4360: "Standards Australian, Risk
Management" in earlier editions of the present document.
[i.22] ISO/IEC 18028:2005 (Parts 4 and 5): "Information technology -- Security techniques -- IT
network security".
NOTE: ISO/IEC 18028 is a multipart publication and the reference above is used to refer to the series.
[i.23] ETSI ES 202 383: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Security Design Guide; Method and proforma for defining
Security Targets".
[i.24] ETSI ES 202 382: "Telecommunications and Internet converged Services and Protocols for
Advanced Networking (TISPAN); Security Design Guide; Method and proforma for defining
Protection Profiles".
[i.25] ETSI TS 102 165-2 (2007): "Telecommunications and Internet converged Services and Protocols
for Advanced Networking (TISPAN); Methods and protocols; Part 2: Protocol Framework
Definition; Security Counter Measures".
[i.26] ETSI TS 187 001: "Network Technologies (NTECH); NGN SECurity (SEC); Requirements".
[i.27] ISO/IEC 15408-1: "Information technology - Security techniques - Evaluation criteria for IT
security - Part 1: Introduction and general model".
[i.28] ISO/IEC 15408-2: "Information technology - Security techniques - Evaluation criteria for IT
security - Part 2: Security functional requirements".
[i.29] ISO/IEC 15408-3: "Information technology - Security techniques - Evaluation criteria for IT
security - Part 3: Security assurance requirements".
[i.30] ISO/IEC 15408: "Information technology - Security techniques - Evaluation criteria for IT
security".
NOTE: When referring to all parts of ISO/IEC 15408 the reference above is used.
[i.31] ISO/IEC 17799: "Information technology -- Security techniques -- Code of practice for
information security management".
[i.32] Common Methodology for Information Technology Security Evaluation: "Evaluation
methodology", July 2009 Version 3.1 Revision 3 Final.
NOTE: Available at https://www.commoncriteriaportal.org/files/ccfiles/CEMV3.1R3.pdf.
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in ETSI EG 202 387 [i.1],
ISO/IEC 17799 [i.31], ISO/IEC 18028 [i.22] and the following apply:
asset: anything that has value to the organization, its business operations and its continuity
authentication: ensuring that the identity of a subject or resource is the one claimed
availability: property of being accessible and usable on demand by an authorized entity ISO/IEC 18028 [i.22]
confidentiality: ensuring that information is accessible only to those authorized to have access
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11 ETSI TS 102 165-1 V5.2.3 (2017-10)
cyber herd immunity: a form of immunity to attack wherein a critical mass of vulnerable assets are protected against a
certain type of attack such that it becomes unprofitable for attackers to attempt to discover unprotected assets to attack
impact: result of an information security incident, caused by a threat, which affects assets
integrity: safeguarding the accuracy and completeness of information and processing methods
mitigation: limitation of the negative consequences of a particular event
nonce: arbitrary number that is generated for security purposes (such as an initialization vector) that is used only one
time in any security session
NOTE: Although random and pseudo-random numbers theoretically produce unique numbers, there is the
possibility that the same number can be generated more than once.
non-repudiation: ability to prove an action or event has taken place, so that this event or action cannot be repudiated
later
residual risk: risk remaining after risk treatment
risk: potential that a given threat will exploit vulnerabilities of an asset or group of assets and thereby cause harm to the
organization
threat: potential cause of an incident that may result in harm to a system or organization
NOTE 1: A threat consists of an asset, a threat agent and an adverse action of that threat agent on that asset
(clause 6.2 of Common Criteria part 1 - ISO/IEC 15408-1 [i.27]).
NOTE 2: A threat is enacted by a threat agent, and may lead to an unwanted incident breaking certain
pre-defined security objectives.
threat agent: entity that can adversely act on an asset
unwanted incident: incident such as loss of confidentiality, integrity and/or availability
NOTE: See ISO 31000 [i.21].
user: person or process using the system in order to gain access to some system resident or system accessible service
vulnerability: weakness of an asset or group of assets that can be exploited by one or more threats
NOTE: A vulnerability, consistent with the definition given in ISO/IEC 18028 [i.22], is modelled as the
combination of a weakness that can be exploited by one or more threats.
3.2 Symbols
For the purposes of the present document, the symbols given in OMG UML2 [i.14] and the following apply:
Generalization/Specialization: UML concept showing relationship between entities A and B where the
two entities exhibit the property that A (top of arrow) is the general case whereas B is the specific case

EXAMPLE: A countermeasure is a specialized asset.
Composition: UML concept showing relationship between entities A and B where A "is composed of"
B
EXAMPLE: Vulnerability "is composed of" a threat and a weakness.
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12 ETSI TS 102 165-1 V5.2.3 (2017-10)
Dependency: UML concept showing relationship between entities A and B where B is dependent upon
A
EXAMPLE: Security requirements "depend on" security objectives.
Aggregation: UML concept showing relationship between entities A and B where A "is an aggregate of"
B
EXAMPLE: System "is an aggregate of" assets.
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ACK ACKnkowlegement
ANSI American National Standards Institute
ARP Address Resolution Protocol
CC Common Criteria
CIA Confidentiality Integrity Availability
CIAAA Confidentiality, Integrity, Availability, Authenticity and Accountability
CM Configuration Management
CPU Core Processor Unit
DDDS Dynamic Delegation Discovery System
DDoS Distributed Denial of Service
DNS Domaine Name Service
DNSSEC DNS SECurity
DoS Denial of Service
EAL Evaluation Assurance Level
ENUM Electronic NUMbering
ERD Entity Relationship Diagram
FAU Functional class AUdit
NOTE: From ISO/IEC 15408-2 [i.28].
FCO Functional class Communication
NOTE: From ISO/IEC 15408-2 [i.28].
FCS Functional class Cryptographic Support
NOTE: From ISO/IEC 15408-2 [i.28].
FDP Functional class user Data Protection
NOTE: From ISO/IEC 15408-2 [i.28].
FIA Functional class Identification and Authentication
NOTE: From ISO/IEC 15408-2 [i.28].
FMT Functional class Security Management
NOTE: From ISO/IEC 15408-2 [i.28].
FPR Functional class Privacy
NOTE: From ISO/IEC 15408-2 [i.28].
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FPT Functional class Protection of the TSF
NOTE: From ISO/IEC 15408-2 [i.28].
FRU Functional class Resource Utilization
NOTE: From ISO/IEC 15408-2 [i.28].
FTA Functional class TOE Access
NOTE: From ISO/IEC 15408-2 [i.28].
FTP Functional class Trusted Path/Channels
NOTE: From ISO/IEC 15408-2 [i.28].
HTTP Hyper Text Transmission Protocol
ICMP Internet Control Message Protocol
IMS IP Multimedia Subsystem
IN Intelligent Network
IP Internet Protocol
ISO International Standards Orgainsation
IT Information Technology
LAN Local Area Network
NAPTR Naming Authority PoinTeR
NGN Next Generation Network
NTP Network Time Protocol
OSI Open System Interconnection
PP Protection Profile
SIP Session Initiation Protocol
SNMP Simple Network Management Protocol
SQL Structured Query Language
SSH Secure SHell
ST Security Targets
SYN (TCP) SYN(chronize)
TCP Transport Control Protocol
TISPAN Telecommunications and Internet converged Services and Protocols for Advanced Networking
TOE Target Of Evaluation
TSF TOE Security Function
TSP TOE Security Policy
TTP Trusted Third Party
TVRA Threat Vulnerability and Risk Analysis
UDP User Datagram Protocol
UML Unified Modelling Language
URI Uniform Resource Identifiers
4 Introduction
4.1 Role of TVRA
It is recognized that without an understanding of the system, the threats to the system and a systematic countermeasure
cost-benefit analysis that appropriate selection of countermeasures cannot be made. Within ETSI a Threat Vulnerability
and Risk Analysis (TVRA) is used to identify risk to the system based upon the product of the likelihood of an attack,
and the impact that such an attack will have on the system. The TVRA method described in the present document is
primarily aimed at use within the standards domain to give justification for the development of standards based security
solutions. In addition the TVRA may be used as the source of parts of a Protection Profile (PP), see ETSI
ES 202 382 [i.24]. Large parts of the descriptive text of a PP may in turn be derived from the TVRA:
• Security objectives;
• Security requirements;
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14 ETSI TS 102 165-1 V5.2.3 (2017-10)
• Rationale.
The method described in the present document provides a means of documenting the rationale for designing security
countermeasures in a system by application of a systematic method, and by using part of the method to visualize the
relationship of objectives, requirements, system design and system vulnerabilities.
The method systematically addresses those aspects of ICT systems covered by standardization and quantifies their
assets, vulnerabilities and threats. The primary focus of the TVRA is on the assets of a system and it is required to
ensure that they can perform their primary function when subjected to malicious attack. The output of the TVRA is a
quantified measure of the risks to the assets and a set of detailed security requirements that will minimize that risk.
For the purposes of analysis all assets are considered to have weaknesses.
The depth of the TVRA changes as the system design becomes more detailed. A TVRA working from the system
objectives will identify at a very coarse level the required security functionality to ensure that the objectives can be met
without damage to the system. The structure of activities in development of a TVRA is shown in figure 1. The process
is shown as recursive wherein in any change to any aspect of the system or its environment requires the process to be
restarted.
ETSI
15 ETSI TS 102 165-1 V5.2.3 (2017-10)

Establish Security Objectives
Security Assurance
Objectives Objectives
Carry Out Vulnerability Analysis
( Objectives )
Specify Security Requirements
Security
Threats
Requirements
Carry Out Vulnerability Analysis
( Requirements )
System Design
Security
Security
Security Services
Mechanisms
Architecture
Carry Out Vulnerability Analysis
( System )
Key :
Control
Process
Information
Process
Input / Output
Figure 1: Structure of security analysis and development in standards documents
The purpose of the TVRA is to determine how open to attack the system, or components of the sys
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