draft-ietf-dime-e2e-sec-req-03.txt   draft-ietf-dime-e2e-sec-req-04.txt 
DIME H. Tschofenig DIME H. Tschofenig
Internet-Draft ARM Limited Internet-Draft ARM Limited
Intended status: Informational J. Korhonen, Ed. Intended status: Informational J. Korhonen, Ed.
Expires: December 19, 2015 Broadcom Corporation Expires: July 16, 2016 Broadcom Corporation
G. Zorn G. Zorn
Network Zen Network Zen
K. Pillay K. Pillay
Oracle Communications Oracle Communications
June 17, 2015 January 13, 2016
Diameter AVP Level Security End-to-End Security: Scenarios and Diameter AVP Level Security End-to-End Security: Scenarios and
Requirements Requirements
draft-ietf-dime-e2e-sec-req-03.txt draft-ietf-dime-e2e-sec-req-04.txt
Abstract Abstract
This specification discusses requirements for providing Diameter This specification discusses requirements for providing Diameter
security at the level of individual Attribute Value Pairs. security at the level of individual Attribute-Value Pairs.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 19, 2015. This Internet-Draft will expire on July 16, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
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1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Security Threats . . . . . . . . . . . . . . . . . . . . . . 3 3. Security Threats . . . . . . . . . . . . . . . . . . . . . . 3
4. Scenarios for Diameter AVP-Level Protection . . . . . . . . . 5 4. Scenarios for Diameter AVP-Level Protection . . . . . . . . . 5
5. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 7 5. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.1. Normative References . . . . . . . . . . . . . . . . . . 8 9.1. Normative References . . . . . . . . . . . . . . . . . . 8
9.2. Informative References . . . . . . . . . . . . . . . . . 8 9.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction 1. Introduction
The Diameter Base specification [2] offers security protection The Diameter base protocol specification [2] offers security
between neighboring Diameter peers and mandates that either TLS (for protection between neighboring Diameter peers and mandates that peer
TCP), DTLS (for SCTP), or IPsec is used. These security protocols connections must be protected by TLS (for TCP), DTLS (for SCTP) or
offer a wide range of security properties, including entity alternative security mechanisms independent of Diameter (e.g., IPsec)
authentication, data-origin authentication, integrity, is used. These security protocols offer a wide range of security
confidentiality protection and replay protection. They also support properties, including entity authentication, data-origin
a large number of cryptographic algorithms, algorithm negotiation, authentication, integrity, confidentiality protection and replay
and different types of credentials. protection. They also support a large number of cryptographic
algorithms, algorithm negotiation, and different types of
credentials. It should be understood that TLS/DTLS/IPsec in Diameter
context does not provide end-to-end security unless the Diameter
nodes are direct peers i.e., neighboring Diameter nodes. The current
Diameter security is realized hop-by-hop.
The need to also offer additional security protection of AVPs between The need to also offer additional security protection of AVPs between
non-neighboring Diameter nodes was recognized very early in the work non-neighboring Diameter nodes was recognized very early in the work
on Diameter. This led to work on Diameter security using the on Diameter. This led to work on Diameter security using the
Cryptographic Message Syntax (CMS) [3]. Due to lack of deployment Cryptographic Message Syntax (CMS) [3]. Due to lack of deployment
interest at that time (and the complexity of the developed solution) interest at that time (and the complexity of the developed solution)
the specification was, however, never completed. the specification was, however, never completed.
In the meanwhile Diameter had received a lot of deployment interest In the meanwhile Diameter had received a lot of deployment interest
from the cellular operator community and because of the from the cellular operator community and because of the
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specification [2]. specification [2].
In the figures below we use the symbols 'AVP' and '{AVP}k'. AVP In the figures below we use the symbols 'AVP' and '{AVP}k'. AVP
refers to an unprotected AVP and {AVP}k refers to an AVP that refers to an unprotected AVP and {AVP}k refers to an AVP that
experiences security protection (using key "k") without further experiences security protection (using key "k") without further
distinguishing between integrity and confidentiality protection. distinguishing between integrity and confidentiality protection.
3. Security Threats 3. Security Threats
The following description aims to illustrate various security threats The following description aims to illustrate various security threats
that raise the need for protecting Diameter Attribute Value Pairs that raise the need for protecting Diameter Attribute-Value Pairs
(AVPs). Figure 1 illustrates an example Diameter topology where a (AVPs). Figure 1 illustrates an example of Diameter based roaming
Diameter clients want to interact with the example.com home domain. architecture in which Diameter clients within the visited networks
To interconnect the two visited networks a AAA interconnection need to interact with Diameter servers in the home domain. AAA
provider, labeled as AAA Broker, is used. domains are interconnected using a Diameter-based AAA interconnection
network labeled as AAA Broker.
+oooooooooooooooooo+ +====================+ +oooooooooooooooooo+ +====================+
| Example.net | | | | Example.net | | |
| | | | | | | |
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+ +--------+ +--------+
|Diameter| |Diameter+--------+Diameter| |Diameter| |Diameter| |Diameter+--------+Diameter| |Diameter|
|Client 1+------+Proxy A1| +------+Proxy B +--------+Proxy C |----+ |Client 1+------+Proxy A1| +------+Proxy B +--------+Proxy C |----+
+--------+ +--------+ | +--------+ +--------+ | +--------+ +--------+ | +--------+ +--------+ |
| | | | | | | | | | | |
| Visited Domain 1 | | | AAA Broker | | | Visited Domain 1 | | | AAA Broker | |
skipping to change at page 4, line 38 skipping to change at page 4, line 38
| | | |
| Visited Domain 2 | | Visited Domain 2 |
+oooooooooooooooooo+ +oooooooooooooooooo+
Figure 1: Example Diameter Deployment. Figure 1: Example Diameter Deployment.
Eavesdropping: Some Diameter applications carry information that is Eavesdropping: Some Diameter applications carry information that is
only intended for consumption by end points, either by the only intended for consumption by end points, either by the
Diameter client or by the Diameter server but not by Diameter client or by the Diameter server but not by
intermediaries. As an example, consider the Diameter EAP intermediaries. As an example, consider the Diameter EAP
application [4] that allows keying material for the protection of application [4] that allows the transport of keying material
air interface between the end device and the network access server between the Diameter server to the Diameter client (using the EAP-
to be carried from the Diameter server to the Diameter client Master-Session-Key AVP) for the protection of air interface
(using the EAP-Master-Session-Key AVP). The content of the EAP- between the end device and the network access server. The content
Master-Session-Key AVP would benefit from protection against of the EAP-Master-Session-Key AVP should benefit from protection
eavesdropping by intermediaries. Other AVPs might also carry against eavesdropping by intermediaries. Other AVPs, for example
sensitive personal data that, when collected by intermediaries, those listed in Section 13.3 of [2], might also carry sensitive
allow for traffic analysis. personal data that, when collected by intermediaries, allow for
traffic analysis.
In context of the deployment shown in Figure 1 the adversary In context of the deployment shown in Figure 1 the adversary
could, for example, be in the AAA broker network. could, for example, be in the AAA broker network.
Injection and Manipulation: The Diameter base specification mandates Injection and Manipulation: The Diameter base protocol specification
security protection between neighboring nodes but Diameter agents mandates security protection between neighboring nodes but
may be compromised or misconfigured and inject/manipulate AVPs. Diameter agents may be compromised or misconfigured and inject/
To detect such actions additional security protection needs to be manipulate AVPs. To detect such actions additional security
applied at the Diameter layer. protection needs to be applied at the Diameter layer.
Nodes that could launch such an attack are any Diameter agents Nodes that could launch such an attack are any Diameter agents
along the end-to-end communication path. along the end-to-end communication path.
Impersonation: Imagine a case where a Diameter message from Impersonation: Imagine a case where a Diameter message from
Example.net contains information claiming to be from Example.org. Example.net contains information claiming to be from Example.org.
This would either require strict verification at the edge of the This would either require strict verification at the edge of the
AAA broker network or cryptographic assurance at the Diameter AAA broker network or cryptographic assurance at the Diameter
layer to prevent a successful impersonation attack. layer to prevent a successful impersonation attack.
Any Diameter realm could launch such an attack aiming for Any Diameter realm could launch such an attack aiming for
financial benefits or to disrupt service availability. financial benefits or to disrupt service availability.
4. Scenarios for Diameter AVP-Level Protection 4. Scenarios for Diameter AVP-Level Protection
This scenario outlines a number of cases for deploying security This scenario outlines a number of cases for deploying security
protection of individual Diameter AVPs. protection of individual Diameter AVPs.
In the first scenario, shown in Figure 2, end-to-end security In the first scenario, shown in Figure 2, end-to-end security
protection is provided between the Diameter client and the Diameter protection is provided between the Diameter client and the Diameter
server. Diameter AVPs exchanged between these two Diameter nodes are server with any number of intermediate Diameter agents. Diameter
protected. AVPs exchanged between these two Diameter nodes may be protected end-
to-end (notation '{AVP}k') or unprotected (notation 'AVP').
+--------+ +--------+ +--------+ +--------+
|Diameter| AVP, {AVP}k |Diameter| |Diameter| AVP, {AVP}k |Diameter|
|Client +-----------------........... -------------------+Server | |Client +-----------------........... -------------------+Server |
+--------+ +--------+ +--------+ +--------+
Figure 2: End-to-End Diameter AVP Security Protection. Figure 2: End-to-End Diameter AVP Security Protection.
In the second scenario, shown in Figure 3, a Diameter proxy acts on In the second scenario, shown in Figure 3, a Diameter proxy acts on
behalf of the Diameter client with regard to security protection. It behalf of the Diameter client with regard to security protection. It
applies security protection to outgoing Diameter AVPs and verifies applies security protection to outgoing Diameter AVPs and verifies
incoming AVPs. incoming AVPs. Typically, the proxy enforcing the security
protection belongs to the same domain as the Diameter client/server
without end-to-end security features.
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+
|Diameter| AVP |Diameter| AVP, {AVP}k |Diameter| |Diameter| AVP |Diameter| AVP, {AVP}k |Diameter|
|Client +-----+Proxy A +---------- .......... -----------+Server | |Client +-----+Proxy A +---------- .......... -----------+Server |
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+
Figure 3: Middle-to-End Diameter AVP Security Protection. Figure 3: Middle-to-End Diameter AVP Security Protection.
In the third scenario shown in Figure 4 a Diameter proxy acts on In the third scenario shown in Figure 4 a Diameter proxy acts on
behalf of the Diameter server. behalf of the Diameter server.
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+--------+ +--------+ +--------+ +--------+ +--------+ +--------+
Figure 4: End-to-Middle Diameter AVP Security Protection. Figure 4: End-to-Middle Diameter AVP Security Protection.
The fourth and the final scenario (see Figure 5) is a combination of The fourth and the final scenario (see Figure 5) is a combination of
the end-to-middle and the middle-to-end scenario shown in Figure 4 the end-to-middle and the middle-to-end scenario shown in Figure 4
and in Figure 3. From a deployment point of view this scenario is and in Figure 3. From a deployment point of view this scenario is
easier to accomplish for two reasons: First, Diameter clients and easier to accomplish for two reasons: First, Diameter clients and
Diameter servers remain unmodified. This ensures that no Diameter servers remain unmodified. This ensures that no
modifications are needed to the installed Diameter infrastructure. modifications are needed to the installed Diameter infrastructure.
Second, key management is also simplified since fewer number of key Second, key management is also simplified since fewer number of keys
pairs need to be negotiated and provisioned. need to be negotiated and provisioned.
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+ +--------+ +--------+
|Diameter| AVP |Diameter| AVP, {AVP}k |Diameter| AVP |Diameter| |Diameter| AVP |Diameter| AVP, {AVP}k |Diameter| AVP |Diameter|
|Client +-----+Proxy A +-- .......... ----+Proxy D +-----+Server | |Client +-----+Proxy A +-- .......... ----+Proxy D +-----+Server |
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+ +--------+ +--------+
Figure 5: Middle-to-Middle Diameter AVP Security Protection. Figure 5: Middle-to-Middle Diameter AVP Security Protection.
Various security threats are mitigated by selectively applying Various security threats are mitigated by selectively applying
security protection for individual Diameter AVPs. Without protection security protection for individual Diameter AVPs. Without protection
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Modification of certain Diameter AVPs may not necessarily be the act Modification of certain Diameter AVPs may not necessarily be the act
of malicious behavior but could also be the result of of malicious behavior but could also be the result of
misconfiguration. An over-aggressively configured firewalling misconfiguration. An over-aggressively configured firewalling
Diameter proxy may also remove certain AVPs. In most cases data Diameter proxy may also remove certain AVPs. In most cases data
origin authentication and integrity protection of AVPs will provide origin authentication and integrity protection of AVPs will provide
the most benefits for existing deployments with minimal overhead and the most benefits for existing deployments with minimal overhead and
(potentially) operating in a full-backwards compatible manner. (potentially) operating in a full-backwards compatible manner.
5. Requirements 5. Requirements
Requirement #1: Solutions MUST support an extensible set of Requirement #1: The solution MUST support an extensible set of
cryptographic algorithms. cryptographic algorithms.
Motivation: Solutions MUST be able to evolve to adapt to Motivation: Solutions MUST be able to evolve to adapt to
evolving cryptographic algorithms and security requirements. evolving cryptographic algorithms and security requirements.
This may include the provision of a modular mechanism to allow This may include the provision of a modular mechanism to allow
cryptographic algorithms to be updated without substantial cryptographic algorithms to be updated without substantial
disruption to deployed implementations. disruption to deployed implementations.
Requirement #2: Solutions MUST support confidentiality, integrity, Requirement #2: The solution MUST support confidentiality,
and data-origin authentication. Solutions for integrity integrity, and data-origin authentication. Solutions for
protection MUST work in a backwards-compatible way with existing integrity protection MUST work in a backwards-compatible way with
Diameter applications. existing Diameter applications.
Requirement #3: Solutions MUST support replay protection. All Requirement #3: The solution MUST support replay protection. All
Diameter nodes have access to network time and thus can Diameter nodes have access to network time and thus can
synchronize their clocks. synchronize their clocks.
Requirement #4: Solutions MUST support the ability to delegate Requirement #4: The solution MUST support the ability to delegate
security functionality to another entity security functionality to another entity
Motivation: As described in Section 4 the ability to let a Motivation: As described in Section 4 the ability to let a
Diameter proxy to perform security services on behalf of all Diameter proxy to perform security services on behalf of all
clients within the same administrative domain is important for clients within the same administrative domain is important for
incremental deployability. The same applies to the other incremental deployability. The same applies to the other
communication side where a load balancer terminates security communication side where a load balancer terminates security
services for the servers it interfaces. services for the servers it interfaces.
Requirement #5: Solutions MUST be able to selectively apply their Requirement #5: The solution MUST be able to selectively apply their
cryptographic protection to certain Diameter AVPs. cryptographic protection to certain Diameter AVPs.
Motivation: Some Diameter applications assume that certain AVPs Motivation: Some Diameter applications assume that certain AVPs
are added, removed, or modified by intermediaries. As such, it are added, removed, or modified by intermediaries. As such, it
MUST be possible to apply security protection selectively. MUST be possible to apply security protection selectively.
Furthermore, there are AVPs that MUST NOT be confidentiality Furthermore, there are AVPs that MUST NOT be confidentiality
protected but MAY still be integrity protected such as those protected but MAY still be integrity protected such as those
required for Diameter message routing. required for Diameter message routing.
Requirement #6: Solutions MUST recommend a mandatory-to-implement Requirement #6: The solution MUST define a mandatory-to-implement
cryptographic algorithm. cryptographic algorithm.
Motivation: For interoperability purposes it is beneficial to Motivation: For interoperability purposes it is beneficial to
have a mandatory-to-implement cryptographic algorithm specified have a mandatory-to-implement cryptographic algorithm specified
(unless profiles for specific usage environments specify (unless profiles for specific usage environments specify
otherwise). otherwise).
Requirement #7: Solutions MUST support symmetric keys and asymmetric Requirement #7: The solution MUST support symmetric keys and
keys. asymmetric keys.
Motivation: Symmetric and asymmetric cryptographic algorithms Motivation: Symmetric and asymmetric cryptographic algorithms
provide different security services. Asymmetric algorithms, provide different security services. Asymmetric algorithms,
for example, allow non-repudiation services to be offered. for example, allow non-repudiation services to be offered.
Requirement #8: A solution for dynamic key management MUST be Requirement #8: A solution for dynamic key management MUST be
included in the overall solution framework. However, it is included in the overall solution framework.
assumed that no "new" key management protocol needs to be
developed; instead existing ones are re-used, if at all possible. However, it is assumed that no "new" key management protocol
Rekeying could be triggered by (a) management actions and (b) needs to be developed; instead existing ones are re-used, if at
expiring keying material. all possible. Rekeying could be triggered by (a) management
actions and (b) expiring keying material.
6. Security Considerations 6. Security Considerations
This entire document focused on the discussion of new functionality This entire document focused on the discussion of new functionality
for securing Diameter AVPs selectively between non-neighboring nodes. for securing Diameter AVPs selectively between non-neighboring nodes.
7. IANA Considerations 7. IANA Considerations
This document does not require actions by IANA. This document does not require actions by IANA.
8. Acknowledgments 8. Acknowledgments
We would like to thank Guenther Horn, Martin Dolly, Steve Donovan and We would like to thank Guenther Horn, Martin Dolly, Steve Donovan,
Tom Taylor for their review comments. Lionel Morand and Tom Taylor (rest in peace Tom) for their review
comments.
9. References 9. References
9.1. Normative References 9.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate [1] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[2] Fajardo, V., Arkko, J., Loughney, J., and G. Zorn, [2] Fajardo, V., Ed., Arkko, J., Loughney, J., and G. Zorn,
"Diameter Base Protocol", RFC 6733, October 2012. Ed., "Diameter Base Protocol", RFC 6733,
DOI 10.17487/RFC6733, October 2012,
<http://www.rfc-editor.org/info/rfc6733>.
9.2. Informative References 9.2. Informative References
[3] Calhoun, P., Farrell, S., and W. Bulley, "Diameter CMS [3] Calhoun, P., Farrell, S., and W. Bulley, "Diameter CMS
Security Application", draft-ietf-aaa-diameter-cms-sec-04 Security Application", draft-ietf-aaa-diameter-cms-sec-04
(work in progress), March 2002. (work in progress), March 2002.
[4] Eronen, P., Hiller, T., and G. Zorn, "Diameter Extensible [4] Eronen, P., Ed., Hiller, T., and G. Zorn, "Diameter
Authentication Protocol (EAP) Application", RFC 4072, Extensible Authentication Protocol (EAP) Application",
August 2005. RFC 4072, DOI 10.17487/RFC4072, August 2005,
<http://www.rfc-editor.org/info/rfc4072>.
Authors' Addresses Authors' Addresses
Hannes Tschofenig Hannes Tschofenig
ARM Limited ARM Limited
Austria Austria
Email: Hannes.tschofenig@gmx.net Email: Hannes.tschofenig@gmx.net
URI: http://www.tschofenig.priv.at URI: http://www.tschofenig.priv.at
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