ETSI GS NFV-SEC 022 V2.7.1 (2020-01)

Network Functions Virtualisation (NFV) Release 2; Security; Access Token Specification for API Access

RGS/NFV-SEC022ed271

General Information

• Status: Published
• Publication Date: 06-Jan-2020
• Technical Committee: NFV SEC - Security
• Current Stage: 12 - Completion
• Due Date: 03-Feb-2020
• Completion Date: 07-Jan-2020

Standards Content (Sample)

ETSI GS NFV-SEC 022 V2.7.1 (2020-01)






GROUP SPECIFICATION
Network Functions Virtualisation (NFV) Release 2;
Security;
Access Token Specification for API Access
Disclaimer
The present document has been produced and approved by the Network Functions Virtualisation (NFV) ETSI Industry
Specification Group (ISG) and represents the views of those members who participated in this ISG.
It does not necessarily represent the views of the entire ETSI membership.

---------------------- Page: 1 ----------------------
2 ETSI GS NFV-SEC 022 V2.7.1 (2020-01)



Reference
RGS/NFV-SEC022ed271
Keywords
API, authentication, authorization, NFV, security

ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE

Tel.: [phone]  Fax: [phone]

Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88

Important notice
The present document can be downloaded from:
http://www.etsi.org/standards-search
The present document may be made available in electronic versions and/or in print. The content of any electronic and/or
print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any
existing or perceived difference in contents between such versions and/or in print, the prevailing version of an ETSI
deliverable is the one made publicly available in PDF format at www.etsi.org/deliver.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
https://portal.etsi.org/TB/ETSIDeliverableStatus.aspx
If you find errors in the present document, please send your comment to one of the following services:
https://portal.etsi.org/People/CommiteeSupportStaff.aspx
Copyright Notification
No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying
and microfilm except as authorized by written permission of ETSI.
The content of the PDF version shall not be modified without the written authorization of ETSI.
The copyright and the foregoing restriction extend to reproduction in all media.

© ETSI 2020.
All rights reserved.

DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its Members.

3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and
of the 3GPP Organizational Partners.
oneM2M™ logo is a trademark of ETSI registered for the benefit of its Members and
of the oneM2M Partners.
®
GSM and the GSM logo are trademarks registered and owned by the GSM Association.
ETSI

---------------------- Page: 2 ----------------------
3 ETSI GS NFV-SEC 022 V2.7.1 (2020-01)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 8
3 Definition of terms, symbols and abbreviations . 8
3.1 Terms . 8
3.2 Symbols . 8
3.3 Abbreviations . 8
4 Security requirements for API access tokens . 9
4.1 Authorization for API access using OAuth2.0 defined in ETSI GS NFV-SOL 013 . 9
4.1.0 Authorization for API access using OAuth2.0 . 9
4.1.1 Mapping roles for Authorization for API access using OAuth2.0 . 9
4.1.2 Authorization grant for Authorization for API access using OAuth2.0 . 9
4.1.3 High level procedures for API access and notifications using OAuth2.0 . 9
4.1.4 Access token for API access and notifications using OAuth2.0 . 10
4.2 Threat Analysis . 11
4.2.0 Access token defined in ETSI GS NFV-SOL 013 . 11
4.2.1 Risk analysis and assessment . 11
4.3 Security requirements . 16
5 NFV Access Token Definition . 18
5.1 Authorization Server discovery . 18
5.1.1 Authorization Server discovery description . 18
5.1.2 Manual Authorization Server Identifier discovery . 19
5.1.3 Dynamic Authorization Server Identifier discovery . 19
5.1.4 Authorization Server Configuration discovery . 20
5.2 Registration process . 22
5.2.1 Disposition . 22
5.2.2 Registration process description . 23
5.2.3 Client metadata . 23
5.3 Token Request . 25
5.4 NFV Access Token Format . 26
5.5 NFV access token associated Metadata . 27
6 Token Verification Process . 29
Annex A (informative): Analysis of existing Access Token specifications . 30
®
A.1 OpenStack Keystone . 30
A.1.0 Introduction . 30
A.1.1 Authorization scopes . 30
A.1.2 Token binding . 30
A.1.3 Fernet token . 30
A.1.4 Fernet keys . 31
A.1.5 Advantage of Fernet tokens . 31
®
A.2 OpenID Connect ID-Token . 31
A.2.0 Introduction . 31
A.2.1 ID Token . 32
A.2.2 Advantage of ID Token . 32
A.3 IETF TLS-Based AccessToken Binding . 33
ETSI

---------------------- Page: 3 ----------------------
4 ETSI GS NFV-SEC 022 V2.7.1 (2020-01)
A.3.0 Introduction . 33
A.3.1 OAuth 2.0 Token Binding . 33
A.3.1.1 Token Binding ID . 33
A.3.1.2 Token Binding for ID Token . 33
A.3.1.3 Advantage of Token Binding . 34
A.3.1.4 Security considerations . 34
A.3.1.4.1 Security Token Replay . 34
A.3.1.4.2 Downgrade attacks . 34
A.3.2 OAuth 2.0 Certificate Bound Access Tokens . 34
A.3.2.0 Basic principle . 34
A.3.2.1 Certificate bound access token using JWT . 34
A.3.3 OAuth 2.0 Token Binding and OAuth2.0 Certificate Token binding comparison . 35
A.4 3GPP authorization framework . 35
A.4.0 OAuth 2.0 authorization in 3GPP . 35
A.4.1 Authentication between Network Functions . 35
A.4.2 Access Token Request . 36
A.4.3 3GPP Access Token . 36
A.4.4 Service access request . 36
Annex B (informative): Synthesis on existing Access Token . 37
Annex C (informative): IANA Registry Considerations . 45
C.1 "Well-Known URIs" Registry . 45
C.1.1 Introduction . 45
C.1.2 Registry contents . 45
C.2 JSON Web Token Claims registry . 45
C.2.1 Introduction . 45
C.2.2 Registry contents . 45
C.3 OAuth Parameters registry . 46
C.3.1 Introduction . 46
C.3.2 Registry contents . 46
C.4 OAuth Dynamic Client Registration Metadata registry . 46
C.4.1 Introduction . 46
C.4.2 Registry contents . 46
C.5 OAuth Authorization Server Metadata registry . 47
C.5.1 Introduction . 47
C.5.2 Registry contents . 47
Annex D (informative): Change History . 48
History . 49


ETSI

---------------------- Page: 4 ----------------------
5 ETSI GS NFV-SEC 022 V2.7.1 (2020-01)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables 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
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
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 Group Specification (GS) has been produced by ETSI Industry Specification Group (ISG) Network Functions
Virtualisation (NFV) .
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 common aspects for RESTful NFV MANO APIs have been defined in ETSI GS NFV-SOL 013 [22].
The ETSI NFV-MANO APIs are only allowed to be accessed by authorized consumers.
The Authorization of API Request and Authorization of notifications sending has been defined in SOL group. One
solution for authorizing access is the use of OAuth with access token.
The aim of the present document is to define the Access Token for this access Authorization and associated procedure
for the verification of the Access Token, ensuring security and interoperability. The present document results in a NFV
profile of the OAuth2.0 for the NFV-MANO API Request and notification sending Authorization.


ETSI

---------------------- Page: 5 ----------------------
6 ETSI GS NFV-SEC 022 V2.7.1 (2020-01)
1 Scope
The present document defines the access tokens and related metadata for RESTful protocols and data model for ETSI
NFV management and orchestration (MANO) interfaces. It defines also the process for the token verification by the
API Producer.
For this aim, the present document:
• Analyses the security threat arising from the misuse of the access token and defines the security requirements
associated to access token.
• Analyses existing specifications related to access token for API access and their compliancy with the
requirements defined.
• Defines the token request and generation profile, the token format and associated metadata considering the
result of existing access token specifications analysis.
• Defines the token verification procedures for the API Producer.
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.
[1] ETSI GS NFV 003: "Network Functions Virtualisation (NFV); Terminology for Main Concepts in
NFV".
[2] ETSI GS NFV-SEC 002: "Network Functions Virtualisation (NFV); NFV Security; Cataloguing
security features in management software".
[3] ETSI GS NFV-IFA 007: "Network Functions Virtualisation (NFV) Release 2; Management and
Orchestration; Or-Vnfm reference point - Interface and Information Model Specification".
[4] ETSI GS NFV-IFA 013: "Network Functions Virtualisation (NFV) Release 2; Management and
Orchestration; Os-Ma-Nfvo reference point - Interface and Information Model Specification".
[5] ETSI GS NFV-IFA 008: "Network Functions Virtualisation (NFV) Release 2; Management and
Orchestration; Ve-Vnfm reference point - Interface and Information Model Specification".
[6] IETF RFC 6749: "The OAuth 2.0 Authorization Framework".
NOTE: Available at https://tools.ietf.org/html/rfc6749.
[7] IETF RFC 6750: "The OAuth 2.0 Authorization Framework: Bearer Token Usage".
NOTE: Available at https://tools.ietf.org/html/rfc6750.
[8] IETF RFC 7519: "JSON Web Token (JWT)".
NOTE: Available at https://tools.ietf.org/html/rfc7519.
ETSI

---------------------- Page: 6 ----------------------
7 ETSI GS NFV-SEC 022 V2.7.1 (2020-01)
[9] IETF RFC 3339: "Date and Time on the Internet: Timestamps".
NOTE: Available at https://tools.ietf.org/html/rfc3339.
[10] IETF RFC 7515: "JSON Web Signature (JWS)".
NOTE: Available at https://tools.ietf.org/html/rfc7515.
[11] IETF RFC 7516: "JSON Web Encryption (JWE)".
NOTE: Available at https://tools.ietf.org/html/rfc7516.
[12] NIST Special Publication 800-90B: "Recommendation for the Entropy Sources Used for Random
Bit Generation", January 2018.
NOTE: Available at https://nvlpubs.nist.gov/nistpubs/specialpublications/nist.sp.800-90b.pdf.
[13] IETF RFC 8414: "OAuth 2.0 Authorization Server Metadata".
NOTE: Available at https://tools.ietf.org/html/rfc8414.
[14] IETF RFC 7033: "WebFinger".
NOTE: Available at https://tools.ietf.org/html/rfc7033.
[15] ETSI GS NFV-IFA 011: "Network Functions Virtualisation (NFV) Release 2; Management and
Orchestration; VNF Descriptor and Packaging Specification".
[16] IETF RFC 3986: "Uniform Resource Identifier (URI): Generic Syntax".
NOTE: Available at https://tools.ietf.org/html/rfc3986.
[17] IETF RFC 8615: "Well-Known Uniform Resource Identifiers (URIs)".
NOTE: Available at https://www.rfc-editor.org/info/rfc8615.
[18] IETF RFC 7591: "OAuth 2.0 Dynamic Client Registration Protocol".
NOTE: Available at https://tools.ietf.org/html/rfc7591.
[19] IETF RFC 7517: "JSON Web Key (JWK)".
NOTE: Available at https://tools.ietf.org/html/rfc7517.
[20] IETF RFC 7518: "JSON Web Algorithms (JWA)".
NOTE: Available at https://tools.ietf.org/html/rfc7518.
[21] IETF RFC 7662: "OAuth 2.0 Token Introspection".
NOTE: Available at https://tools.ietf.org/html/rfc7662.
[22] ETSI GS NFV-SOL 013: "Network Functions Virtualisation (NFV) Release 2; Protocols and Data
Models; Specification of common aspects for RESTful NFV MANO APIs".
[23] draft-ietf-oauth-mtls-17: "OAuth 2.0 Mutual TLS Client Authentication and Certificate-Bound
Access Tokens". Work in progress.
NOTE: Available at https://tools.ietf.org/wg/oauth/draft-ietf-oauth-mtls/.
[24] ETSI GS NFV-IFA 005: "Network Functions Virtualisation (NFV) Release 2; Management and
Orchestration; Or-Vi reference point - Interface and Information Model Specification".
[25] ETSI GS NFV-IFA 006: "Network Functions Virtualisation (NFV) Release 2; Management and
Orchestration; Vi-Vnfm reference point - Interface and Information Model Specification".
ETSI

---------------------- Page: 7 ----------------------
8 ETSI GS NFV-SEC 022 V2.7.1 (2020-01)
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] https://docs.openstack.org/keystone/latest/admin/tokens.html.
[i.2] https://openid.net/specs/openid-connect-core-1_0.html#IDToken.
[i.3] IETF RFC 8471: "The Token Binding Protocol Version 1.0".
NOTE: Available at https://tools.ietf.org/html/rfc8471.
[i.4] IETF RFC 6819: "OAuth 2.0 Threat Model and Security Considerations".
NOTE: Available at https://tools.ietf.org/html/rfc6819.
[i.5] ETSI GS NFV-SEC 006: "Network Functions Virtualisation (NFV); Security Guide; Report on
Security Aspects and Regulatory Concerns".
[i.6] ETSI TS 133 501: "5G; Security architecture and procedures for 5G System (3GPP TS 33.501)".
[i.7] draft-ietf-oauth-token-binding-08: "OAuth 2.0 Token Binding", Work in progress.
NOTE: Available at https://tools.ietf.org/pdf/draft-ietf-oauth-token-binding-08.pdf.
3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the terms given in ETSI GS NFV 003 [1] apply.
3.2 Symbols
Void.
3.3 Abbreviations
For the purposes of the present document, the abbreviations given in ETSI GS NFV 003 [1] and the following apply:
rd
3GPP 3 Generation Partnership Project
HSM Hardware Security Module
JRD JSON Resource Descriptor
JSON JavaScript Object Notation
JWE JSON Web Encryption
JWS JSON Web Signature
JWT JSON Web Token
MAC Message Authentication Code
MTLS Mutual TLS
NRF Network Resource Function
OTP One-Time Password
PKI Public Key Infrastructure
ETSI

---------------------- Page: 8 ----------------------
9 ETSI GS NFV-SEC 022 V2.7.1 (2020-01)
REST REpresentational State Transfer
SAML Security Assertion Markup Language
TLS Transport Layer Security
URI Uniform Resource Identifier
URL Uniform Resource Locator
4 Security requirements for API access tokens
4.1 Authorization for API access using OAuth2.0 defined in
ETSI GS NFV-SOL 013
4.1.0 Authorization for API access using OAuth2.0
The requirements on interfaces supported by the reference point of MANO's entities have been defined in ETSI
GS NFV-IFA 005 [24], ETSI GS NFV-IFA 006 [25], ETSI GS NFV-IFA 007 [3], ETSI GS NFV-IFA 013 [4] and ETSI
GS NFV-IFA 008 [5].
One of these requirements concerns authentication and authorization of the API consumer for all operations on
interfaces supported by the reference point.
To fulfil this requirement for the NFV-MANO reference points, authorization of API requests and notifications has
been defined in ETSI GS NFV-SOL 013 [22] specification.
One solution defined to handle these authorizations for API request and notification is the use of OAuth 2.0 protocol as
defined by IETF RFC 6749 [6].
4.1.1 Mapping roles for Authorization for API access using OAuth2.0
For API calls, the producer functional block of an API in NFV terms corresponds to the "resource server", and the
consumer functional block of an API corresponds to the "client" as defined by IETF RFC 6749 [6]. For sending a
notification, these roles are reversed: The producer (notification sender) corresponds to the "client", and the consumer
(notification receiver) corresponds to the "resource server".
Before invoking an HTTP method on a REST resource provided by a resource server, a consumer functional block
(referred to as "client" from now on) first obtains authorization from another functional block fulfilling the role of the
"authorization server".
4.1.2 Authorization grant for Authorization for API access using OAuth2.0
Authorization grant, which is a credential representing the resource owner's authorization to access the API resources is
used by the client to obtain an access token from the authorization server as defined by IETF RFC 6749 [6]. OAuth 2.0
defined 4 types of authorization grant (authorization code, implicit, resource owner password credentials, and client
credentials).
For the reference points listed in clause 4.1, access to API is performed by a machine which is a non-interactive Client,
acting on its own behalf and being the Resource owner. Example of such client is the EM requesting the creation of an
instance of its related VNF to the corresponding VNFM; this EM is the resource owner for the management resource of
the VNF. The authorization grant suitable to this case is the client credentials authorization grant. This is the
authorization grant type that has been selected for the NFV-MANO interfaces and defined in ETSI
GS NFV-SOL 013 [22].
4.1.3 High level procedures for API access and notifications using
OAuth2.0
The roles and exchanges are shown in figure 4.1.3-1 in case of API calls and in figure 4.1.3-2 for sending a notification.
ETSI

---------------------- Page: 9 ----------------------
...