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Versions: 00 01 02 03 04 05 06 RFC 7258
Network Working Group S. Farrell
Internet-Draft Trinity College Dublin
Intended status: BCP H. Tschofenig
Expires: June 23, 2014 December 20, 2013
Pervasive Monitoring is an Attack
draft-farrell-perpass-attack-03.txt
Abstract
Pervasive monitoring is a technical attack that should be mitigated
in the design of IETF protocols, where possible.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on June 23, 2014.
Copyright Notice
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1. Pervasive Monitoring is Indistinguishable from an Attack
The technical plenary of the November 2013 IETF meeting
[IETF88Plenary] discussed pervasive monitoring (or surveillance)
which requires the monitoring party to take actions that are
indistinguishable from an attack on Internet communications.
Participants at that meeting therefore expressed strong agreement
that this was an attack that should be mitigated where possible via
the design of protocols that make pervasive monitoring significantly
more expensive or infeasible. This Best Current Practice (BCP, see
[RFC2026] Section 5) formally documents that consensus.
For the purposes of this document "pervasive monitoring" means often
covert and very widespread intrusive gathering of protocol artefacts
including application content, protocol meta-data such as headers, or
cryptographic keys used to secure protocols. Active or passive
wiretaps, traffic analysis, correlation, timing or measuring packet
sizes can also be used as part of pervasive monitoring.
The term "attack" is used here in a technical sense that differs
somewhat from common English usage. In common English usage, an
"attack" is an aggressive action perpetrated by an opponent, intended
to enforce the opponent's will on the attacked party. Here, the term
is used to refer to a behavior that subverts the intent of a
communicator without the agreement of the parties to the
communication. It may change the content of the communication,
record the content of the communication, or through correlation with
other communication events, reveal information the communicator did
not intend to be revealed. It may also have other effects that
similarly subvert the intent of a communicator. [RFC4949] contains a
more complete definition for the term "attack." We also use the term
in the singular here, even though pervasive monitoring in reality may
require a multi-faceted set of coordinated attacks.
In particular, the term "attack", when used technically, implies
nothing about the motivation of the actor mounting the attack. The
motivation behind pervasive monitoring is not relevant for this
document, but can range from non-targeted nation-state surveillance,
to legal but privacy-unfriendly purposes by commercial enterprises,
to illegal purposes by criminals. The same techniques can be used
regardless of motivation and we cannot defend against the most
nefarious actors while allowing monitoring by other actors no matter
how benevolent some might consider them to be. As technology
advances, techniques that were once only available to extremely well
funded actors become more widely accessible. Mitigating this attack
is therefore a protection against wider usage of pervasive
monitoring.
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2. The IETF will work to Mitigate Pervasive Monitoring
"Mitigation" is a technical term that does not imply an ability to
completely prevent or thwart an attack. Protocols that mitigate
pervasive monitoring will not prevent the attack, but can
significantly change the threat. (See the diagram on page 24 of RFC
4949 for how the terms attack and threat are related.) This can
significantly increase the cost of attacking, force what was covert
to be overt, or make the attack more likely to be detected, possibly
later.
IETF standards already provide mechanisms to protect Internet
communications and there are guidelines [RFC3552] for applying these
in protocol design. But those generally do not consider pervasive
monitoring, the confidentiality of protocol meta-data, countering
traffic analysis nor data minimisation. [RFC6973] And in all cases,
there will remain some privacy-relevant information that is
inevitably disclosed by protocols.
It is nonetheless timely to revisit the security and privacy
properties of our standards. The IETF will work to mitigate the
technical parts of the pervasive monitoring threat, just as we do for
other protocol vulnerabilities. The ways in which IETF protocols
mitigate pervasive monitoring will change over time as mitigation and
attack techniques evolve and so are not described here.
Those developing IETF specifications need to be able to describe how
they have considered pervasive monitoring, and, if the attack is
relevant to the work to be published, be able to justify related
design decisions. This does not mean a new "pervasive monitoring
considerations" section is needed in IETF documentation. It means
that, if asked, there needs to be a good answer to the question "is
pervasive monitoring relevant to this work and if so how has it been
addressed?"
While pervasive monitoring is an attack, other forms of monitoring
can be beneficial and not part of any attack, e.g. network management
functions monitor packets or flows, anti-spam mechanisms see mail
message content and monitoring can even be a mitigation for pervasive
monitoring in the case of Certificate Transparency. [RFC6962] There
is though a clear potential for monitoring mechanisms to be abused
for pervasive monitoring, so this tension needs careful consideration
in protocol design. Making networks unmanageable to mitigate
pervasive monitoring is not an acceptable outcome, but ignoring
pervasive monitoring would go against the consensus documented in
this BCP. An appropriate balance will likely emerge over time as
real instances of this tension are considered.
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Finally, the IETF, as a standards development organisation, does not
control the implementation or deployment of our specifications
(though IETF participants do develop many implementations), nor does
the IETF specify all layers of the protocol stack. And the non-
technical (e.g. legal and political) aspects of mitigating pervasive
monitoring are outside of the scope of the IETF. The broader
Internet community will need to step forward to tackle pervasive
monitoring, if it is to be fully addressed.
3. Process Note
In the past, architectural statements of this sort, e.g., [RFC1984]
and [RFC2804] have been published as joint products of the Internet
Engineering Steering Group (IESG) and the Internet Architecture Board
(IAB). However, since those documents were published, the IETF and
IAB have separated their publication "streams" as described in
[RFC4844] and [RFC5741]. This document was initiated by both the
IESG and IAB, but is published as an IETF-stream consensus document,
in order to ensure that it properly reflects the consensus of the
IETF community as a whole.
[[Note (to be removed before publication): This draft is written as
if IETF consensus has been established for the text.]]
4. Security Considerations
This BCP is entirely about privacy. More information about the
relationship between security and privacy threats can be found in
[RFC6973]. Section 5.1.1 of [RFC6973] specifically addresses
surveillance as a combined security-privacy threat.
5. IANA Considerations
There are none. We hope the RFC editor deletes this section before
publication.
6. Acknowledgements
We would like to thank the participants of the IETF 88 technical
plenary for their feedback. Thanks in particular to the following
for useful suggestions or comments: Jari Arkko, Fred Baker, Marc
Blanchet, Tim Bray, Scott Brim, Randy Bush, Brian Carpenter, Benoit
Claise, Alissa Cooper, Dave Crocker, Spencer Dawkins, Avri Doria,
Wesley Eddy, Adrian Farrel, Joseph Lorenzo Hall, Ted Hardie, Sam
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Hartmann, Bjoern Hoehrmann, Phillip Hallam-Baker, Russ Housley, Joel
Jaeggli, Stephen Kent, Eliot Lear, Barry Leiba, Ted Lemon,
Subrahamian Moonesamy, Erik Nordmark, Pete Resnick, Peter Saint-
Andre, Andrew Sullivan, Sean Turner, and Stefan Winter.
Additionally, we would like to thank all those who contributed
suggestions on how to improve Internet security and privacy or who
commented on this on various IETF mailing lists, such as the
ietf@ietf.org and the perpass@ietf.org lists.
7. Informative References
[IETF88Plenary]
IETF, "IETF 88 Plenary Meeting Materials", URL:
https://datatracker.ietf.org/meeting/88/materials.html,
Nov 2013.
[RFC1984] IAB, IESG, Carpenter, B., and F. Baker, "IAB and IESG
Statement on Cryptographic Technology and the Internet",
RFC 1984, August 1996.
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, October 1996.
[RFC2804] IAB and IESG, "IETF Policy on Wiretapping", RFC 2804,
May 2000.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552,
July 2003.
[RFC4844] Daigle, L. and Internet Architecture Board, "The RFC
Series and RFC Editor", RFC 4844, July 2007.
[RFC4949] Shirey, R., "Internet Security Glossary, Version 2",
RFC 4949, August 2007.
[RFC5741] Daigle, L., Kolkman, O., and IAB, "RFC Streams, Headers,
and Boilerplates", RFC 5741, December 2009.
[RFC6962] Laurie, B., Langley, A., and E. Kasper, "Certificate
Transparency", RFC 6962, June 2013.
[RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
Morris, J., Hansen, M., and R. Smith, "Privacy
Considerations for Internet Protocols", RFC 6973,
July 2013.
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Authors' Addresses
Stephen Farrell
Trinity College Dublin
Dublin, 2
Ireland
Phone: +353-1-896-2354
Email: stephen.farrell@cs.tcd.ie
Hannes Tschofenig
Brussels,
Belgium
Phone:
Email: hannes.tschofenig@gmx.net
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