Challenges and Changes in the Internet Threat Model
draft-arkko-farrell-arch-model-t-01
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draft-arkko-farrell-arch-model-t-01
Network Working Group J. Arkko
Internet-Draft Ericsson
Intended status: Informational S. Farrell
Expires: June 17, 2020 Trinity College Dublin
December 15, 2019
Challenges and Changes in the Internet Threat Model
draft-arkko-farrell-arch-model-t-01
Abstract
Communications security has been at the center of many security
improvements in the Internet. The goal has been to ensure that
communications are protected against outside observers and attackers.
This memo suggests that the existing threat model, while important
and still valid, is no longer alone sufficient to cater for the
pressing security issues in the Internet. For instance, it is also
necessary to protect systems against endpoints that are compromised,
malicious, or whose interests simply do not align with the interests
of the users. While such protection is difficult, there are some
measures that can be taken.
It is particularly important to ensure that as we continue to develop
Internet technology, non-communications security related threats, and
privacy issues, are properly understood.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 17, 2020.
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Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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to this document. Code Components extracted from this document must
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Observations . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1. Communications Security Improvements . . . . . . . . . . 6
2.2. Beyond Communications Security . . . . . . . . . . . . . 6
2.3. Examples . . . . . . . . . . . . . . . . . . . . . . . . 9
2.3.1. Deliberate adversarial behaviour in applications . . 9
2.3.2. Inadvertent adversarial behaviours . . . . . . . . . 13
3. Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.1. The Role of End-to-end . . . . . . . . . . . . . . . . . 14
3.2. Trusted networks . . . . . . . . . . . . . . . . . . . . 16
3.2.1. Even closed networks can have compromised nodes . . . 17
3.3. Balancing Threats . . . . . . . . . . . . . . . . . . . . 18
4. Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.1. Basic Guidelines . . . . . . . . . . . . . . . . . . . . 19
4.2. Potential Further Guidelines . . . . . . . . . . . . . . 21
4.2.1. Consider ABuse-cases as well as use-cases . . . . . . 21
4.2.2. Isolation . . . . . . . . . . . . . . . . . . . . . . 21
4.2.3. Transparency . . . . . . . . . . . . . . . . . . . . 21
4.2.4. Minimise . . . . . . . . . . . . . . . . . . . . . . 22
4.2.5. Same-Origin Policy . . . . . . . . . . . . . . . . . 22
4.2.6. Greasing . . . . . . . . . . . . . . . . . . . . . . 22
4.2.7. Generalise OAuth Threat Model . . . . . . . . . . . . 22
4.2.8. Look again at how well we're securing infrastructure 23
4.2.9. Consider recovery from attack as part of protocol
design . . . . . . . . . . . . . . . . . . . . . . . 23
4.2.10. Don't think in terms of hosts . . . . . . . . . . . . 23
4.2.11. Trusted Computing . . . . . . . . . . . . . . . . . . 24
4.2.12. Trust Boundaries . . . . . . . . . . . . . . . . . . 24
4.3. Does IETF Analysis of Protocols Need to Change? . . . . . 25
4.3.1. Develop a BCP for privacy considerations . . . . . . 25
4.3.2. Re-consider protocol design "lore" . . . . . . . . . 25
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4.3.3. Consider the user perspective . . . . . . . . . . . . 25
4.3.4. Potential changes in RFC 3552 . . . . . . . . . . . . 25
4.3.5. Potential Changes in RFC 7258 . . . . . . . . . . . . 26
5. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 27
6. Informative References . . . . . . . . . . . . . . . . . . . 28
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 35
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36
1. Introduction
Communications security has been at the center of many security
improvements in the Internet. The goal has been to ensure that
communications are protected against outside observers and attackers.
At the IETF, this approach has been formalized in BCP 72 [RFC3552],
which defined the Internet threat model in 2003.
The purpose of a threat model is to outline what threats exist in
order to assist the protocol designer. But RFC 3552 also ruled some
threats to be in scope and of primary interest, and some threats out
of scope [RFC3552]:
The Internet environment has a fairly well understood threat
model. In general, we assume that the end-systems engaging in a
protocol exchange have not themselves been compromised.
Protecting against an attack when one of the end-systems has been
compromised is extraordinarily difficult. It is, however,
possible to design protocols which minimize the extent of the
damage done under these circumstances.
By contrast, we assume that the attacker has nearly complete
control of the communications channel over which the end-systems
communicate. This means that the attacker can read any PDU
(Protocol Data Unit) on the network and undetectably remove,
change, or inject forged packets onto the wire.
However, the communications-security -only threat model is becoming
outdated. This is due to three factors:
o Advances in protecting most of our communications with strong
cryptographic means. This has resulted in much improved
communications security, but also highlights the need for
addressing other, remaining issues. This is not to say that
communications security is not important, it still is:
improvements are still needed. Not all communications have been
protected, and even out of the already protected communications,
not all of their aspects have been fully protected. Fortunately,
there are ongoing projects working on improvements.
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o Adversaries have increased their pressure against other avenues of
attack, from compromising devices to legal coercion of centralized
endpoints in conversations.
o New adversaries and risks have arisen, e.g., due to creation of
large centralized information sources.
o While communications-security does seem to be required to protect
privacy, more is needed.
In short, attacks are migrating towards the currently easier targets,
which no longer necessarily include direct attacks on traffic flows.
In addition, trading information about users and ability to influence
them has become a common practice for many Internet services, often
without users understanding those practices.
This memo suggests that the existing threat model, while important
and still valid, is no longer alone sufficient to cater for the
pressing security issues in the Internet. For instance, while it
continues to be very important to protect Internet communications
against outsiders, it is also necessary to protect systems against
endpoints that are compromised, malicious, or whose interests simply
do not align with the interests of the users.
Of course, there are many trade-offs in the Internet on who one
chooses to interact with and why or how. It is not the role of this
memo to dictate those choices. But it is important that we
understand the implications of different practices. It is also
important that when it comes to basic Internet infrastructure, our
chosen technologies lead to minimal exposure with respect to the non-
communications threats.
It is particularly important to ensure that non-communications
security related threats are properly understood for any new Internet
technology. While the consideration of these issues is relatively
new in the IETF, this memo provides some initial ideas about
potential broader threat models to consider when designing protocols
for the Internet or when trying to defend against pervasive
monitoring. Further down the road, updated threat models could
result in changes in BCP 72 [RFC3552] (guidelines for writing
security considerations) and BCP 188 [RFC7258] (pervasive
monitoring), to include proper consideration of non-communications
security threats.
It may also be necessary to have dedicated guidance on how systems
design and architecture affect security. The sole consideration of
communications security aspects in designing Internet protocols may
lead to accidental or increased impact of security issues elsewhere.
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For instance, allowing a participant to unnecessarily collect or
receive information may lead to a similar effect as described in
[RFC8546] for protocols: over time, unnecessary information will get
used with all the associated downsides, regardless of what deployment
expectations there were during protocol design.
This memo does not stand alone. To begin with, it is a merge of
earlier work by the two authors [I-D.farrell-etm]
[I-D.arkko-arch-internet-threat-model]. There are also other
documents discussing this overall space, e.g.
[I-D.lazanski-smart-users-internet] [I-D.arkko-arch-dedr-report].
The authors of this memo envisage independent development of each of
those (and other work) with an eventual goal to extract an updated
(but usefully brief!) description of an extended threat model from
the collection of works. We consider it an open question whether
this memo, or any of the others, would be usefully published as an
RFC.
The rest of this memo is organized as follows. Section 2 makes some
observations about the situation, with respect to communications
security and beyond. The section also provides a number of real-
world examples.
Section 3 discusses some high-level implications that can be drawn,
such as the need to consider what the "ends" really are in an "end-
to-end" communication.
Section 4 discusses some potential remedies, both from the point of
view of a system design, as well as from the point of IETF procedures
and recommended analysis procedures when designing new protocols.
For instance, Section 4.1 will also discuss high-level guidance to
addressing these threats, and Section 4.3.4 suggests some potential
changes to the definition of the IETF's "Internet Threat Model". It
is also apparent that the dangers posed by pervasive monitoring need
to be taken in a broader light, given the evolution of the threats
beyond communications security.
Comments are solicited on these and other aspects of this document.
The best place for discussion is on the arch-discuss list
(https://www.ietf.org/mailman/listinfo/Architecture-discuss).
Finally, Section 5 draws some conclusions for next steps.
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2. Observations
2.1. Communications Security Improvements
Being able to ask about threat model improvements is due to progress
already made: The fraction of Internet traffic that is
cryptographically protected has grown tremendously in the last few
years. Several factors have contributed to this change, from Snowden
revelations to business reasons and to better available technology
such as HTTP/2 [RFC7540], TLS 1.3 [RFC8446], QUIC
[I-D.ietf-quic-transport].
In many networks, the majority of traffic has flipped from being
cleartext to being encrypted. Reaching the level of (almost) all
traffic being encrypted is no longer something unthinkable but rather
a likely outcome in a few years.
At the same time, technology developments and policy choices have
driven the scope of cryptographic protection from protecting only the
pure payload to protecting much of the rest as well, including far
more header and meta-data information than was protected before. For
instance, efforts are ongoing in the IETF to assist encrypting
transport headers [I-D.ietf-quic-transport], server domain name
information in TLS [I-D.ietf-tls-esni], and domain name queries
[RFC8484].
There have also been improvements to ensure that the security
protocols that are in use actually have suitable credentials and that
those credentials have not been compromised, see, for instance, Let's
Encrypt [RFC8555], HSTS [RFC6797], HPKP [RFC7469], and Expect-CT
[I-D.ietf-httpbis-expect-ct].
This is not to say that all problems in communications security have
been resolved - far from it. But the situation is definitely
different from what it was a few years ago. Remaining issues will be
and are worked on; the fight between defense and attack will also
continue. Communications security will stay at the top of the agenda
in any Internet technology development.
2.2. Beyond Communications Security
There are, however, significant issues beyond communications security
in the Internet. To begin with, it is not necessarily clear that one
can trust all the endpoints in any protocol interaction.
Of course, the endpoints were never trusted, but the pressures
against endpoints issues seem to be mounting. For instance, the
users may not be in as much control over their own devices as they
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used to be due to manufacturer-controlled operating system
installations and locked device ecosystems. And within those
ecosystems, even the applications that are available tend to have
privileges that users by themselves would most likely not desire
those applications have, such as excessive rights to media, location,
and peripherals. There are also designated efforts by various
authorities to hack end-user devices as a means of intercepting data
about the user.
The situation is different, but not necessarily better on the side of
servers. The pattern of communications in today's Internet is almost
always via a third party that has at least as much information as the
other parties have. For instance, these third parties are typically
endpoints for any transport layer security connections, and able to
see any communications or other messaging in cleartext. There are
some exceptions, of course, e.g., messaging applications with end-to-
end protection.
With the growth of trading users' information by many of these third
parties, it becomes necessary to take precautions against endpoints
that are compromised, malicious, or whose interests simply do not
align with the interests of the users.
Specifically, the following issues need attention:
o Security of users' devices and the ability of the user to control
their own equipment.
o Leaks and attacks related to data at rest.
o Coercion of some endpoints to reveal information to authorities or
surveillance organizations, sometimes even in an extra-territorial
fashion.
o Application design patterns that result in cleartext information
passing through a third party or the application owner.
o Involvement of entities that have no direct need for involvement
for the sake of providing the service that the user is after.
o Network and application architectures that result in a lot of
information collected in a (logically) central location.
o Leverage and control points outside the hands of the users or end-
user device owners.
For instance, while e-mail transport security [RFC7817] has become
much more widely distributed in recent years, progress in securing
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e-mail messages between users has been much slower. This has lead to
a situation where e-mail content is considered a critical resource by
some mail service providers who use the content for machine learning,
advertisement targeting, and other purposes unrelated to message
delivery. Equally however, it is unclear how some useful anti-spam
techniques could be deployed in an end-to-end encrypted mail universe
(with today's end-to-end mail sercurity protocols).
The Domain Name System (DNS) shows signs of ageing but due to the
legacy of deployed systems has changed very slowly. Newer technology
[RFC8484] developed at the IETF enables DNS queries to be performed
confidentially, but its initial deployment is happening mostly in
browsers that use global DNS resolver services, such as Cloudflare's
1.1.1.1 or Google's 8.8.8.8. This results in faster evolution and
better security for end users.
However, if one steps back and considers the potential security and
privacy effects of these developments, the outcome could appear
different. While the security and confidentiality of the protocol
exchanges improves with the introduction of this new technology, at
the same time this could lead to a move from using a worldwide
distributed set of DNS resolvers into a far smaller set of
centralised global resolvers. While these resolvers are very well
maintained (and a great service), they are potential high-value
targets for pervasive monitoring and Denial-of-Service (DoS) attacks.
In 2016, for example, DoS attacks were launched against Dyn, one of
the largest DNS providers, leading to some outages. It is difficult
to imagine that DNS resolvers wouldn't be a target in many future
attacks or pervasive monitoring projects.
Unfortunately, there is little that even large service providers can
do to not be a DDoS target, not to refuse authority-sanctioned
pervasive monitoring. As a result it seems that a reasonable defense
strategy may be to aim for outcomes where such highly centralised
control points are unecessary or don't handle sensitive data.
(Recalling that with the DNS, information about the requestor and the
act of requesting an answer are what is potentially sensitive, rather
than the content of the answer.)
There are other examples of the perils of centralised solutions in
Internet infrastructure. The DNS example involves an interesting
combination of information flows (who is asking for what domain
names) as well as a potential ability to exert control (what domains
will actually resolve to an address). Routing systems are primarily
about control. While there are intra-domain centralized routing
solutions (such as PCE [RFC4655]), a control within a single
administrative domain is usually not the kind of centralization that
we would be worried about. Global centralization would be much more
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concerning. Fortunately, global Internet routing is performed a
among peers. However, controls could be introduced even in this
global, distributed system. To secure some of the control exchanges,
the Resource Public Key Infrastructure (RPKI) system ([RFC6480])
allows selected Certification Authorities (CAs) to help drive
decisions about which participants in the routing infrastructure can
make what claims. If this system were globally centralized, it would
be a concern, but again, fortunately, current designs involve at
least regional distribution.
In general, many recent attacks relate more to information than
communications. For instance, personal information leaks typically
happen via information stored on a compromised server rather than
capturing communications. There is little hope that such attacks can
be prevented entirely. Again, the best course of action seems to be
avoid the disclosure of information in the first place, or at least
to not perform that in a manner that makes it possible that others
can readily use the information.
2.3. Examples
2.3.1. Deliberate adversarial behaviour in applications
In this section we describe a few documented examples of deliberate
adversarial behaviour by applications that could affect Internet
protocol development. The adversarial behaviours described below
involve various kinds of attack, varying from simple fraud, to
credential theft, surveillance and contributing to DDoS attacks.
This is not intended to be a comprehensive nor complete survey, but
to motivate us to consider deliberate adversarial behaviour by
applications.
While we have these examples of deliberate adversarial behaviour,
there are also many examples of application developers doing their
best to protect the security and privacy of their users or customers.
That's just the same as the case today where we need to consider in-
network actors as potential adversaries despite the many examples of
network operators who do act primarily in the best interests of their
users.
2.3.1.1. Malware in curated application stores
Despite the best efforts of curators, so-called App-Stores frequently
distribute malware of many kinds and one recent study [Curated]
claims that simple obfuscation enables malware to avoid detection by
even sophisticated operators. Given the scale of these deployments,
distribution of even a small percentage of malware-infected
applictions can affect a huge number of people.
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2.3.1.2. Virtual private networks (VPNs)
Virtual private networks (VPNs) are supposed to hide user traffic to
various degrees depending on the particular technology chosen by the
VPN provider. However, not all VPNs do what they say, some for
example misrepresenting the countries in which they provide vantage
points [Vpns].
2.3.1.3. Compromised (home) networks
What we normally might consider network devices such as home routers
do also run applications that can end up being adversarial, for
example running DNS and DHCP attacks from home routers targeting
other devices in the home. One study [Home] reports on a 2011 attack
that affected 4.5 million DSL modems in Brazil. The absence of
software update [RFC8240] has been a major cause of these issues and
rises to the level that considering this as intentional behaviour by
device vendors who have chosen this path is warranted.
2.3.1.4. Web browsers
Tracking of users in order to support advertising based business
models is ubiquitous on the Internet today. HTTP header fields (such
as cookies) are commonly used for such tracking, as are structures
within the content of HTTP responses such as links to 1x1 pixel
images and (ab)use of Javascript APIs offered by browsers [Tracking].
While some people may be sanguine about this kind of tracking, others
consider this behaviour unwelcome, when or if they are informed that
it happens, [Attitude] though the evidence here seems somewhat harder
to interpret and many studies (that we have found to date) involve
small numbers of users. Historically, browsers have not made this
kind of tracking visible and have enabled it by default, though some
recent browser versions are starting to enable visibility and
blocking of some kinds of tracking. Browsers are also increasingly
imposing more stringent requirements on plug-ins for varied security
reasons.
2.3.1.5. Web site policy deception
Many web sites today provide some form of privacy policy and terms of
service, that are known to be mostly unread [Unread]. This implies
that, legal fiction aside, users of those sites have not in reality
agreed to the specific terms published and so users are therefore
highly exposed to being exploited by web sites, for example
[Cambridge] is a recent well-publicised case where a service provider
abused the data of 87 million users via a partnership. While many
web site operators claim that they care deeply about privacy, it
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seems prudent to assume that some (or most?) do not in fact care
about user privacy, or at least not in ways with which many of their
users would agree. And of course, today's web sites are actually
mostly fairly complex web applications and are no longer static sets
of HTML files, so calling these "web sites" is perhaps a misnomer,
but considered as web applications, that may for example link in
advertising networks, it seems clear that many exist that are
adversarial.
2.3.1.6. Tracking bugs in mail
Some mail user agents (MUAs) render HTML content by default (with a
subset not allowing that to be turned off, perhaps particularly on
mobile devices) and thus enable the same kind of adversarial tracking
seen on the web. Attempts at such intentional tracking are also seen
many times per day by email users - in one study [Mailbug] the
authors estimated that 62% of leakage to third parties was
intentional, for example if leaked data included a hash of the
recipient email address.
2.3.1.7. Troll farms in online social networks
Online social network applications/platforms are well-known to be
vulnerable to troll farms, sometimes with tragic consequences where
organised/paid sets of users deliberately abuse the application
platform for reasons invisible to a normal user. For-profit
companies building online social networks are well aware that subsets
of their "normal" users are anything but. In one US study, [Troll]
sets of troll accounts were roughly equally distributed on both sides
of a controversial discussion. While Internet protocol designers do
sometimes consider sybil attacks [Sybil], arguably we have not
provided mechanisms to handle such attacks sufficiently well,
especially when they occur within walled-gardens. Equally, one can
make the case that some online social networks, at some points in
their evolution, appear to have prioritised counts of active users so
highly that they have failed to invest sufficient effort for
detection of such troll farms.
2.3.1.8. Smart televisions
There have been examples of so-called "smart" televisions spying on
their owners and one survey of user attitudes [SmartTV] found "broad
agreement was that it is unacceptable for the data to be repurposed
or shared" although the level of user understanding may be
questionable. What is clear though is that such devices generally
have not provided controls for their owners that would allow them to
meaningfully make a decision as to whether or not they want to share
such data.
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2.3.1.9. Internet of things
Internet of Things (IoT) devices (which might be "so-called Internet
of Things" as all devices were already things:-) have been found
deficient when their security and privacy aspects were analysed, for
example children's toys [Toys]. While in some cases this may be due
to incompetence rather than being deliberately adversarial behaviour,
the levels of incompetence frequently seen imply these aspects have
simply not been considered a priority.
2.3.1.10. Attacks leveraging compromised high-level DNS infrastructure
Recent attacks [DeepDive] against DNS infrastructure enable
subsequent targetted attacks on specific application layer sources or
destinations. The general method appears to be to attack DNS
infrastructure, in these cases infrastructure that is towards the top
of the DNS naming hierarchy and "far" from the presumed targets, in
order to be able to fake DNS responses to a PKI, thereby acquiring
TLS server certificates so as to subsequently attack TLS connections
from clients to services (with clients directed to an attacker-owned
server via additional fake DNS responses).
Attackers in these cases seem well resourced and patient - with
"practice" runs over months and with attack durations being
infrequent and short (e.g. 1 hour) before the attacker withdraws.
These are sophisticated multi-protocol attacks, where weaknesses
related to deployment of one protocol (DNS) bootstrap attacks on
another protocol (e.g. IMAP/TLS), via abuse of a 3rd protocol
(ACME), partly in order to capture user IMAP login credentials, so as
to be able to harvest message store content from a real message
store.
The fact that many mail clients regularly poll their message store
means that a 1-hour attack is quite likely to harvest many cleartext
passwords or crackable password hashes. The real IMAP server in such
a case just sees fewer connections during the "live" attack, and some
additional connections later. Even heavy email users in such cases
that might notice a slight gap in email arrivals, would likely
attribute that to some network or service outage.
In many of these cases the paucity of DNSSEC-signed zones (about 1%
of existing zones) and the fact that many resolvers do not enforce
DNSSEC validation (e.g., in some mobile operating systems) assisted
the attackers.
It is also notable that some of the personnel dealing with these
attacks against infrastructure entites are authors of RFCs and
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Internet-drafts. That we haven't provided protocol tools that better
protect against these kinds of attack ought hit "close to home" for
the IETF.
In terms of the overall argument being made here, the PKI and DNS
interactions, and the last step in the "live" attack all involve
interaction with a deliberately adversarial application. Later, use
of acquired login credentials to harvest message store content
involves an adversarial client application. It all cases, a TLS
implementation's PKI and TLS protocol code will see the fake
endpoints as protocol-valid, even if, in the real world, they are
clearly fake. This appears to be a good argument that our current
threat model is lacking in some respect(s), even as applied to our
currently most important security protocol (TLS).
2.3.1.11. BGP hijacking
There is a clear history of BGP hijacking [BgpHijack] being used to
ensure endpoints connect to adversarial applications. As in the
previous example, such hijacks can be used to trick a PKI into
issuing a certificate for a fake entity. Indeed one study
[HijackDet] used the emergence of new web server TLS key pairs during
the event, (detected via Internet-wide scans), as a distinguisher
between one form of deliberate BGP hijacking and indadvertent route
leaks.
2.3.2. Inadvertent adversarial behaviours
Not all adversarial behaviour by applications is deliberate, some is
likely due to various levels of carelessness (some quite
understandable, others not) and/or due to erroneous assumptions about
the environments in which those applications (now) run.
We very briefly list some such cases:
o Application abuse for command and control, for example, use of IRC
or apache logs for [CommandAndControl]
o Carelessly leaky data stores [LeakyBuckets], for example, lots of
Amazon S3 leaks showing that careless admins can too easily cause
application server data to become available to adversaries
o Virtualisation exposing secrets, for example, Meltdown and Spectre
[MeltdownAndSpectre] [Kocher2019] [Lipp2018] and other similar
side-channel attacks.
o Compromised badly-maintained web sites, that for example, have led
to massive online [Passwords].
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o Supply-chain attacks, for example, the [TargetAttack] or malware
within pre-installed applications on Android phones [Bloatware].
o Breaches of major service providers, that many of us might have
assumed would be sufficiently capable to be the best large-scale
"Identity providers", for example:
* 3 billion accounts: https://www.wired.com/story/yahoo-breach-
three-billion-accounts/
* "up to 600M" account passwords stored in clear:
https://www.pcmag.com/news/367319/facebook-stored-up-to-600m-
user-passwords-in-plain-text
* many millions at risk: https://www.zdnet.com/article/us-telcos-
caught-selling-your-location-data-again-senator-demands-new-
laws/
* 50 million accounts: https://www.cnet.com/news/facebook-breach-
affected-50-million-people/
* 14 million accounts: https://www.zdnet.com/article/millions-
verizon-customer-records-israeli-data/
* "hundreds of thousands" of accounts:
https://www.wsj.com/articles/google-exposed-user-data-feared-
repercussions-of-disclosing-to-public-1539017194
* unknown numbers, some email content exposed:
https://motherboard.vice.com/en_us/article/ywyz3x/hackers-
could-read-your-hotmail-msn-outlook-microsoft-customer-support
o Breaches of smaller service providers: Too many to enumerate,
sadly
3. Analysis
3.1. The Role of End-to-end
[RFC1958] notes that "end-to-end functions can best be realised by
end-to-end protocols":
The basic argument is that, as a first principle, certain required
end-to-end functions can only be performed correctly by the end-
systems themselves. A specific case is that any network, however
carefully designed, will be subject to failures of transmission at
some statistically determined rate. The best way to cope with
this is to accept it, and give responsibility for the integrity of
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communication to the end systems. Another specific case is end-
to-end security.
The "end-to-end argument" was originally described by Saltzer et al
[Saltzer]. They said:
The function in question can completely and correctly be
implemented only with the knowledge and help of the application
standing at the endpoints of the communication system. Therefore,
providing that questioned function as a feature of the
communication system itself is not possible.
These functional arguments align with other, practical arguments
about the evolution of the Internet under the end-to-end model. The
endpoints evolve quickly, often with simply having one party change
the necessary software on both ends. Whereas waiting for network
upgrades would involve potentially a large number of parties from
application owners to multiple network operators.
The end-to-end model supports permissionless innovation where new
innovation can flourish in the Internet without excessive wait for
other parties to act.
But the details matter. What is considered an endpoint? What
characteristics of Internet are we trying to optimize? This memo
makes the argument that, for security purposes, there is a
significant distinction between actual endpoints from a user's
interaction perspective (e.g., another user) and from a system
perspective (e.g., a third party relaying a message).
This memo proposes to focus on the distinction between "real ends"
and other endpoints to guide the development of protocols. A
conversation between one "real end" to another "real end" has
necessarily different security needs than a conversation between,
say, one of the "real ends" and a component in a larger system. The
end-to-end argument is used primarily for the design of one protocol.
The security of the system, however, depends on the entire system and
potentially multiple storage, compute, and communication protocol
aspects. All have to work properly together to obtain security.
For instance, a transport connection between two components of a
system is not an end-to-end connection even if it encompasses all the
protocol layers up to the application layer. It is not end-to-end,
if the information or control function it carries actually extends
beyond those components. For instance, just because an e-mail server
can read the contents of an e-mail message does not make it a
legitimate recipient of the e-mail.
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This memo also proposes to focus on the "need to know" aspect in
systems. Information should not be disclosed, stored, or routed in
cleartext through parties that do not absolutely need to have that
information.
The proposed argument about real ends is as follows:
Application functions are best realised by the entities directly
serving the users, and when more than one entity is involved, by
end-to-end protocols. The role and authority of any additional
entities necessary to carry out a function should match their part
of the function. No information or control roles should be
provided to these additional entities unless it is required by the
function they provide.
For instance, a particular piece of information may be necessary for
the other real endpoint, such as message contents for another user.
The same piece of information may not be necessary for any additional
parties, unless the information had to do with, say, routing
information for the message to reach the other user. When
information is only needed by the actual other endpoint, it should be
protected and be only relayed to the actual other endpoint. Protocol
design should ensure that the additional parties do not have access
to the information.
Note that it may well be that the easiest design approach is to send
all information to a third party and have majority of actual
functionality reside in that third party. But this is a case of a
clear tradeoff between ease of change by evolving that third party
vs. providing reasonable security against misuse of information.
Note that the above "real ends" argument is not limited to
communication systems. Even an application that does not communicate
with anyone else than its user may be implemented on top of a
distributed system where some information about the user is exposed
to untrusted parties.
The implications of the system security also extend beyond
information and control aspects. For instance, poorly design
component protocols can become DoS vectors which are then used to
attack other parts of the system. Availability is an important
aspect to consider in the analysis along other aspects.
3.2. Trusted networks
Some systems are thought of as being deployed only in a closed
setting, where all the relevant nodes are under direct control of the
network administrators. Technologies developed for such networks
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tend to be optimized, at least initially, for these environments, and
may lack security features necessary for different types of
deployments.
It is well known that many such systems evolve over time, grow, and
get used and connected in new ways. For instance, the collaboration
and mergers between organizations, and new services for customers may
change the system or its environment. A system that used to be truly
within an administrative domain may suddenly need to cross network
boundaries or even run over the Internet. As a result, it is also
well known that it is good to ensure that underlying technologies
used in such systems can cope with that evolution, for instance, by
having the necessary security capabilities to operate in different
environments.
In general, the outside vs. inside security model is outdated for
most situations, due to the complex and evolving networks and the
need to support mixture of devices from different sources (e.g., BYOD
networks). Network virtualization also implies that previously clear
notions of local area networks and physical proximity may create an
entirely different reality from what appears from a simple notion of
a local network.
Similarly, even trusted, well-managed parties can be problematic,
even when operating openly in the Internet. Systems that collect
data from a large number of Internet users, or that are used by a
large number of devices have some inherent issues: large data stores
attract attempts to use that data in a manner that is not consistent
with the users' interests. They can also become single points of
failure through network management, software, or business failures.
See also [I-D.arkko-arch-infrastructure-centralisation].
3.2.1. Even closed networks can have compromised nodes
This memo argues that the situation is even more dire than what was
explained above. It is impossible to ensure that all components in a
network are actually trusted. Even in a closed network with
carefully managed components there may be compromised components, and
this should be factored into the design of the system and protocols
used in the system.
For instance, during the Snowden revelations it was reported that
internal communication flows of large content providers were
compromised in an effort to acquire information from large numbers of
end users. This shows the need to protect not just communications
targeted to go over the Internet, but in many cases also internal and
control communications.
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Furthermore, there is a danger of compromised nodes, so
communications security alone will be insufficient to protect against
this. The defences against this include limiting information within
networks to the parties that have a need to know, as well as limiting
control capabilities. This is necessary even when all the nodes are
under the control of the same network manager; the network manager
needs to assume that some nodes and communications will be
compromised, and build a system to mitigate or minimise attacks even
under that assumption.
Even airgapped networks can have these issues, as evidenced, for
instance, by the Stuxnet worm. The Internet is not the only form of
connectivity, as most systems include, for instance, USB ports that
proved to be the achilles heel of the targets in the Stuxnet case.
More commonly, every system runs large amount of software, and it is
often not practical or even possible to prevent compromised code even
in a high-security setting, let alone in commercial or private
networks. Installation media, physical ports, both open source and
proprietary programs, firmware, or even innocent-looking components
on a circuit board can be suspect. In addition, complex underlying
computing platforms, such as modern CPUs with underlying security and
management tools are prone to problems.
In general, this means that one cannot entirely trust even a closed
system where you picked all the components yourself. Analysis for
the security of many interesting real-world systems now commonly
needs to include cross-component attacks, e.g., the use of car radios
and other externally communicating devices as part of attacks
launched against the control components such as breaks in a car
[Savage].
3.3. Balancing Threats
Note that not all information needs to be protected, and not all
threats can be protected against. But it is important that the main
threats are understood and protected against.
Sometimes there are higher-level mechanisms that provide safeguards
for failures. For instance, it is very difficult in general to
protect against denial-of-service against compromised nodes on a
communications path. However, it may be possible to detect that a
service has failed.
Another example is from packet-carrying networks. Payload traffic
that has been properly protected with encryption does not provide
much value to an attacker. For instance, it does not always make
sense to encrypt every packet transmission in a packet-carrying
system where the traffic is already encrypted at other layers. But
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it almost always makes sense to protect control communications and to
understand the impacts of compromised nodes, particularly control
nodes.
4. Actions
This section discusses potential actions to be taken by the Internet
community:
4.1. Basic Guidelines
As [RFC3935] says:
We embrace technical concepts such as decentralized control, edge-
user empowerment and sharing of resources, because those concepts
resonate with the core values of the IETF community.
To be more specific, this memo suggests the following guidelines for
protocol designers:
1. Consider first principles in protecting information and systems,
rather than following a specific pattern such as protecting
information in a particular way or at a particular protocol
layer. It is necessary to understand what components can be
compromised, where interests may or may not be aligned, and what
parties have a legitimate role in being a party to a specific
information or a control task.
2. Once you have something, do not pass it onto others without
serious consideration: In other words, minimize information
passed to others. Information passed to another party in a
protocol exchange should be minimized to guard against the
potential compromise of that party.
3. Perform end-to-end protection via other parties: Information
passed via another party who does not intrinsically need the
information to perform its function should be protected end-to-
end to its intended recipient. This guideline is general, and
holds equally for sending TCP/IP packets, TLS connections, or
application-layer interactions. As [RFC8546] notes, it is a
useful design rule to avoid "accidental invariance" (the
deployment of on-path devices that over-time start to make
assumptions about protocols). However, it is also a necessary
security design rule to avoid "accidental disclosure" where
information originally thought to be benign and untapped over-
time becomes a significant information leak. This guideline can
also be applied for different aspects of security, e.g.,
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confidentiality and integrity protection, depending on what the
specific need for information is in the other parties.
4. Minimize passing of control functions to others: Any passing of
control functions to other parties should be minimized to guard
against the potential misuse of those control functions. This
applies to both technical (e.g., nodes that assign resources) and
process control functions (e.g., the ability to allocate number
or develop extensions). Control functions can also become a
matter of contest and power struggle, even in cases where their
function as such is minimal, as we saw with the IANA transition
debates.
5. Avoid centralized resources: While centralized components,
resources, and function provide usually a useful function, there
are grave issues associated with them. Protocol and network
design should balance the benefits of centralized resources or
control points against the threats arising from them. The
general guideline is to avoid such centralized resources when
possible. And if it is not possible, find a way to allow the
centralized resources to be selectable, depending on context and
user settings.
6. Have explicit agreements: When users and their devices provide
information to network entities, it would be beneficial to have
an opportunity for the users to state their requirements
regarding the use of the information provided in this way. While
the actual use of such requirements and the willingness of
network entities to agree to them remains to be seen, at the
moment even the technical means of doing this are limited. For
instance, it would be beneficial to be able to embed usage
requirements within popular data formats.
7. Treat parties that your equipment connects to with suspicion,
even if the communications are encrypted. The other endpoint may
misuse any information or control opportunity in the
communication. Similarly, even parties within your own system
need to be treated with suspicision, as some nodes may become
compromised.
8. Do not take any of this as blanket reason to provide no
information to anyone, encrypt everything to everyone, or other
extreme measures. However, the designers of a system need to be
aware of the different threats facing their system, and deal with
the most serious ones (of which there are typically many).
Similarly, users should be aware of the choices made in a
particular design, and avoid designs or products that protect
against some threats but are wide open to other serious issues.
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4.2. Potential Further Guidelines
4.2.1. Consider ABuse-cases as well as use-cases
Protocol developers and those implementing and deploying Internet
technologies are typically most interested in a few specific use-
cases for which they need solutions. Expanding our threat model to
include adversarial application behaviours [AbuseCases] seems likely
to call for significant attention to be paid to potential abuses of
whatever new or re-purposed technology is being considered.
4.2.2. Isolation
Sophisticated users can sometimes deal with adversarial behaviours in
applications by using different instances of those applications, for
example, differently configured web browsers for use in different
contexts. Applications (including web browsers) and operating
systems are also building in isolation via use of different processes
or sandboxing. Protocol artefacts that relate to uses of such
isolation mechanisms might be worth considering. To an extent, the
IETF has in practice already recognised some of these issues as being
in-scope, e.g. when considering the linkability issues with
mechanisms such as TLS session tickets, or QUIC connection
identifiers.
4.2.3. Transparency
Certificate transparency (CT) [RFC6962] has been an effective
countermeasure for X.509 certificate mis-issuance, which used be a
known application layer misbehaviour in the public web PKI. CT can
also help with post-facto detection of some infrastructure attacks
where BGP or DNS weakenesses have been leveraged so that some
certification authority is tricked into issuing a certificate for the
wrong entity.
While the context in which CT operates is very constrained
(essentially to the public CAs trusted by web browsers), similar
approaches could perhaps be useful for other protocols or
technologies.
In addition, legislative requirements such as those imposed by the
GDPR [GDPRAccess] could lead to a desire to handle internal data
structures and databases in ways that are reminiscent of CT, though
clearly with significant authorisation being required and without the
append-only nature of a CT log.
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4.2.4. Minimise
As recommended in [RFC6973] data minimisation and additional
encryption are likely to be helpful - if applications don't ever see
data, or a cleartext form of data, then they should have a harder
time misbehaving. Similarly, not adding new long-term identifiers,
and not exposing existing ones, would seem helpful.
4.2.5. Same-Origin Policy
The Same-Origin Policy (SOP) [RFC6454] perhaps already provides an
example of how going beyond the RFC 3552 threat model can be useful.
Arguably, the existence of the SOP demonstrates that at least web
browsers already consider the 3552 model as being too limited.
(Clearly, differentiating between same and not-same origins
implicitly assumes that some origins are not as trustworthy as
others.)
4.2.6. Greasing
The TLS protocol [RFC8446] now supports the use of GREASE
[I-D.ietf-tls-grease] as a way to mitigate on-path ossification.
While this technique is not likely to prevent any deliberate
misbehaviours, it may provide a proof-of-concept that network
protocol mechanisms can have impact in this space, if we spend the
time to try analyse the incentives of the various parties.
4.2.7. Generalise OAuth Threat Model
The OAuth threat model [RFC6819] provides an extensive list of
threats and security considerations for those implementing and
deploying OAuth version 2.0 [RFC6749]. That document is perhaps too
detailed to serve as useful generic guidance but does go beyond the
Internet threat model from RFC3552, for example it says:
two of the three parties involved in the OAuth protocol may
collude to mount an attack against the 3rd party. For example,
the client and authorization server may be under control of an
attacker and collude to trick a user to gain access to resources.
It could be useful to attempt to derive a more abstract threat model
from that RFC that considers threats in more generic multi-party
contexts.
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4.2.8. Look again at how well we're securing infrastructure
Some attacks (e.g. against DNS or routing infrastructure) appear to
benefit from current infrastructure mechanisms not being deployed,
e.g. DNSSEC, RPKI. In the case of DNSSEC, deployment is still
minimal despite much time having elapsed. This suggests a number of
different possible avenues for investigation:
o For any protocol dependent on infrastructure like DNS or BGP, we
ought analysse potential outcomes in the event the relevant
infrastructure has been compromised
o Protocol designers perhaps ought consider post-facto detection
compromise mechanisms in the event that it is infeasible to
mitigate attacks on infrastructure that is not under local control
o Despite the sunk costs, it may be worth re-considering
infrastructure security mechanisms that have not been deployed,
and hence are ineffective.
4.2.9. Consider recovery from attack as part of protocol design
Recent work on multiparty messaging security primitives
[I-D.ietf-mls-architecture] considers "post-compromise security" as
an inherent part of the design of that protocol. Perhaps protocol
designers ought generally consider recovery from attack during
protocol design - we do know that all widely used protocols will at
sometime be subject to successful attack, whether that is due to
deployment or implementation error, or, as is less common, due to
protocol design flaws.
4.2.10. Don't think in terms of hosts
More and more, protocol endpoints are not being executed on what used
be understood as a host system. The web and Javascript model clearly
differs from traditional host models, but so do most server-side
deployments these days, thanks to virtualisation.
As yes unpublished work on this topic within the IAB [StackEvo]
programme, appears to posit the same kind of thesis. In the stackevo
case, that work would presumably lead to some new definition of
protocol endpoint, but (consensus on) such a definition may not be
needed for an expanded threat model. For this work, it may be
sufficient to note that protocol endpoints can no longer be
considered to be executing on a traditional host, to assume (at
protocol design time) that all endpoints will be run in a virtualised
environment where co-tenants and (sometimes) hypervisors are
adversaries, and to then call for analysis of such scenarios.
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4.2.11. Trusted Computing
Various trusted computing mechanisms allow placing some additional
trust on a particular endpoint. This can be useful to address some
of the issues in this memo:
o A network manager of a set of devices may be assured that the
devices have not been compromised.
o An outside party may be assured that someone who runs a device
employs a particular software installation in that device, and
that the software runs in a protected environment.
IETF work such as TEEP [I-D.ietf-teep-architecture]
[I-D.ietf-teep-protocol] and RATS [I-D.ietf-rats-eat] may be helpful
in providing attestations to other nodes about a particular endpoint,
or lifecycle management of such endpoints.
One should note, however, that it is often not possible to fully
protect endpoints (see, e.g., [Kocher2019] [Lipp2018]
[I-D.taddei-smart-cless-introduction]
[I-D.mcfadden-smart-endpoint-taxonomy-for-cless]). And of course, a
trusted computing may be set up and controlled by a party that itself
is not trusted; a client that contacts a server that the server's
owner runs in a trusted computing setting does not change the fact
that the client and the server's owner may have different interests.
As a result, there is a need to prepare for the possibility that
another party in a communication is not entirely trusted.
4.2.12. Trust Boundaries
Traditional forms of communication equipment have morphed into
today's virtualized environments, where new trust boundaries exist,
e.g., between different virtualisation layers. And an application
might consider itself trusted while not entirely trusting the
underlying operating system. A browser application wants to protect
itself against Javascript loaded from a website, while the website
considers itself and the Javascript an application that it wants to
protect from the browser.
In general, there are multiple parties even in a single device, with
differing interests, including some that have (or claim to) the
interest of the human user in mind.
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4.3. Does IETF Analysis of Protocols Need to Change?
It may also be necessary to make procedural changes in how new
protocols are defined at the IETF. For instance, our existing
documentation of threat models and requirements for security
considerations sections may not be adequate in today's world.
These suggested changes are entirely tentative.
4.3.1. Develop a BCP for privacy considerations
It may be time for the IETF to develop a BCP for privacy
considerations, possibly starting from [RFC6973].
4.3.2. Re-consider protocol design "lore"
It could be that this discussion demonstrates that it is timely to
reconsider some protocol design "lore" as for example is done in
[I-D.iab-protocol-maintenance]. More specifically, protocol
extensibility mechanisms may inadvertently create vectors for abuse-
cases, given that designers cannot fully analyse their impact at the
time a new protocol is defined or standardised. One might conclude
that a lack of extensibility could be a virtue for some new
protocols, in contrast to earlier assumptions. As pointed out by one
commenter though, people can find ways to extend things regardless,
if they feel the need.
4.3.3. Consider the user perspective
[I-D.nottingham-for-the-users] argues that, in relevant cases where
there are conflicting requirements, the "IETF considers end users as
its highest priority concern." Doing so seems consistent with the
expanded threat model being argued for here, so may indicate that a
BCP in that space could also be useful.
4.3.4. Potential changes in RFC 3552
The earlier quote from OAuth (Section 4.2.7) also has another aspect
- it considers the effect of compromised endpoints on those that are
not compromised. It may therefore be interesting to consider the
consequeneces that would follow from a change to [RFC3552]. RFC 3552
is the RFC that defines "An Internet Threat Model". It also provides
guidance to writing Security Considerations sections in other RFCs.
One initial, draft proposal for such changes would be this:
OLD:
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In general, we assume that the end-systems engaging in a protocol
exchange have not themselves been compromised. Protecting against
an attack when one of the end-systems has been compromised is
extraordinarily difficult. It is, however, possible to design
protocols which minimize the extent of the damage done under these
circumstances.
NEW:
In general, we assume that the end-system engaging in a protocol
exchange has not itself been compromised. Protecting against an
attack of a protocol implementation itself is extraordinarily
difficult. It is, however, possible to design protocols which
minimize the extent of the damage done when the other parties in a
protocol become compromised or do not act in the best interests
the end-system implementing a protocol.
In addition, the following new section could be added to discuss the
capabilities required to mount an attack:
NEW:
3.x. Other endpoint compromise
In this attack, the other endpoints in the protocol become
compromised. As a result, they can, for instance, misuse any
information that the end-system implementing a protocol has sent
to the compromised endpoint.
System and architecture aspects definitely also need more attention
from Internet technology developers and standards organizations.
Here is one possible addition:
NEW:
The design of any Internet technology should start from an
understanding of the participants in a system, their roles, and
the extent to which they should have access to information and
ability to control other participants.
4.3.5. Potential Changes in RFC 7258
Other additional guidelines may be necessary also in [RFC7258], the
RFC that specifies how IETF work should take into account pervasive
monitoring, such as the one performed as a part of broad,
indiscriminate surveillance activity.
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An initial, draft suggestion for starting point of those changes
could be adding the following paragraph after the 2nd paragraph in
Section 2:
NEW:
PM attacks include those cases where information collected by a
legitimate protocol participant is misused for PM purposes. The
attacks also include those cases where a protocol or network
architecture results in centralized data storage or control
functions relating to many users, raising the risk of said misuse.
5. Conclusions
At this stage we don't think it approriate to claim that any strong
conclusion can be reached based on the above. We do however, claim
that the is a topic that could be worth discussion and more work.
To start with, Internet technology developers need to be better aware
of the issues beyond communications security, and consider them in
design. At the IETF it would be beneficial to include some of these
considerations in the usual systematic security analysis of
technologies under development.
In particular, when the IETF develops infrastructure technology for
the Internet (such as routing or naming systems), considering the
impacts of data generated by those technologies is important.
Minimising data collection from users, minimising the parties who get
exposed to user data, and protecting data that is relayed or stored
in systems should be a priority.
A key focus area at the IETF has been the security of transport
protocols, and how transport layer security can be best used to
provide the right security for various applications. However, more
work is needed in equivalently broadly deployed tools for minimising
or obfuscating information provided by users to other entities, and
the use of end-to-end security through entities that are involved in
the protocol exchange but who do not need to know everything that is
being passed through them.
Comments on the issues discussed in this memo are gladly taken either
privately or on the model-t mailing list
(https://www.ietf.org/mailman/listinfo/Model-t).
Some further work includes items listed in Section 4.1 and
Section 4.3, as well as compiling categories of vulnerabilities that
need to be addressed, examples of specific attacks, and continuing
the analysis of the situation and possible new remedies.
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It is also necessary find suitable use cases that the IETF can
address by further work in this space. A completely adversial
situation is not really workable, but there are situations where some
parties are trustworthy, and wish to co-operate to show to each other
that this is really the case. In these situations data minimisation
can be beneficial to both, attestation can provide additional trust,
detection of incidents can alert the parties to action, and so on.
6. Informative References
[AbuseCases]
McDermott, J. and C. Fox, "Using abuse case models for
security requirements analysis", IEEE Annual Computer
Security Applications Conference (ACSAC'99),
https://www.acsac.org/1999/papers/wed-b-1030-john.pdf ,
1999.
[Attitude]
"User Perceptions of Sharing, Advertising, and Tracking",
Symposium on Usable Privacy and Security (SOUPS),
https://www.usenix.org/conference/soups2015/proceedings/
presentation/chanchary , 2015.
[BgpHijack]
Sermpezis, P., Kotronis, V., Dainotti, A., and X.
Dimitropoulos, "A survey among network operators on BGP
prefix hijacking", ACM SIGCOMM Computer Communication
Review 48, no. 1 (2018): 64-69,
https://arxiv.org/pdf/1801.02918.pdf , 2018.
[Bloatware]
Gamba, G., Rashed, M., Razaghpanah, A., Tapiado, J., and
N. Vallina, "An Analysis of Pre-installed Android
Software", arXiv preprint arXiv:1905.02713 (2019) , 2019.
[Cambridge]
Isaak, J. and M. Hanna, "User Data Privacy: Facebook,
Cambridge Analytica, and Privacy Protection", Computer
51.8 (2018): 56-59, https://ieeexplore.ieee.org/stamp/
stamp.jsp?arnumber=8436400 , 2018.
[CommandAndControl]
Botnet, ., "Creating botnet C&C server. What architecture
should I use? IRC? HTTP?", Stackexchange.com question,
https://security.stackexchange.com/questions/100577/
creating-botnet-cc-server-what-architecture-should-i-use-
irc-http , 2014.
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[Curated] Hammad, M., Garcia, J., and S. MaleK, "A large-scale
empirical study on the effects of code obfuscations on
Android apps and anti-malware products", ACM International
Conference on Software Engineering 2018,
https://www.ics.uci.edu/~seal/
publications/2018ICSE_Hammad.pdf , 2018.
[DeepDive]
Krebs on Security, ., "A Deep Dive on the Recent
Widespread DNS Hijacking Attacks", krebsonsecurity.com
blog, https://krebsonsecurity.com/2019/02/a-deep-dive-on-
the-recent-widespread-dns-hijacking-attacks/ , 2019.
[GDPRAccess]
EU, ., "Right of access by the data subject", Article 15,
GDPR, https://gdpr-info.eu/art-15-gdpr/ , n.d..
[HijackDet]
Schlamp, J., Holz, R., Gasser, O., Korste, A., Jacquemart,
Q., Carle, G., and E. Biersack, "Investigating the nature
of routing anomalies: Closing in on subprefix hijacking
attacks", International Workshop on Traffic Monitoring and
Analysis, pp. 173-187. Springer, Cham,
https://www.net.in.tum.de/fileadmin/bibtex/publications/
papers/schlamp_TMA_1_2015.pdf , 2015.
[Home] Nthala, N. and I. Flechais, "Rethinking home network
security", European Workshop on Usable Security
(EuroUSEC), https://ora.ox.ac.uk/objects/
uuid:e2460f50-579b-451b-b14e-b7be2decc3e1/download_file?sa
fe_filename=bare_conf_EuroUSEC2018.pdf&file_format=applica
tion%2Fpdf&type_of_work=Conference+item , 2018.
[I-D.arkko-arch-dedr-report]
Arkko, J. and T. Hardie, "Report from the IAB workshop on
Design Expectations vs. Deployment Reality in Protocol
Development", draft-arkko-arch-dedr-report-00 (work in
progress), November 2019.
[I-D.arkko-arch-infrastructure-centralisation]
Arkko, J., "Centralised Architectures in Internet
Infrastructure", draft-arkko-arch-infrastructure-
centralisation-00 (work in progress), November 2019.
[I-D.arkko-arch-internet-threat-model]
Arkko, J., "Changes in the Internet Threat Model", draft-
arkko-arch-internet-threat-model-01 (work in progress),
July 2019.
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[I-D.farrell-etm]
Farrell, S., "We're gonna need a bigger threat model",
draft-farrell-etm-03 (work in progress), July 2019.
[I-D.iab-protocol-maintenance]
Thomson, M., "The Harmful Consequences of the Robustness
Principle", draft-iab-protocol-maintenance-04 (work in
progress), November 2019.
[I-D.ietf-httpbis-expect-ct]
estark@google.com, e., "Expect-CT Extension for HTTP",
draft-ietf-httpbis-expect-ct-08 (work in progress),
December 2018.
[I-D.ietf-mls-architecture]
Omara, E., Beurdouche, B., Rescorla, E., Inguva, S., Kwon,
A., and A. Duric, "The Messaging Layer Security (MLS)
Architecture", draft-ietf-mls-architecture-03 (work in
progress), September 2019.
[I-D.ietf-quic-transport]
Iyengar, J. and M. Thomson, "QUIC: A UDP-Based Multiplexed
and Secure Transport", draft-ietf-quic-transport-24 (work
in progress), November 2019.
[I-D.ietf-rats-eat]
Mandyam, G., Lundblade, L., Ballesteros, M., and J.
O'Donoghue, "The Entity Attestation Token (EAT)", draft-
ietf-rats-eat-01 (work in progress), July 2019.
[I-D.ietf-teep-architecture]
Pei, M., Tschofenig, H., Thaler, D., and D. Wheeler,
"Trusted Execution Environment Provisioning (TEEP)
Architecture", draft-ietf-teep-architecture-05 (work in
progress), December 2019.
[I-D.ietf-teep-protocol]
Tschofenig, H., Pei, M., Wheeler, D., and D. Thaler,
"Trusted Execution Environment Provisioning (TEEP)
Protocol", draft-ietf-teep-protocol-00 (work in progress),
December 2019.
[I-D.ietf-tls-esni]
Rescorla, E., Oku, K., Sullivan, N., and C. Wood,
"Encrypted Server Name Indication for TLS 1.3", draft-
ietf-tls-esni-05 (work in progress), November 2019.
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[I-D.ietf-tls-grease]
Benjamin, D., "Applying GREASE to TLS Extensibility",
draft-ietf-tls-grease-04 (work in progress), August 2019.
[I-D.lazanski-smart-users-internet]
Lazanski, D., "An Internet for Users Again", draft-
lazanski-smart-users-internet-00 (work in progress), July
2019.
[I-D.mcfadden-smart-endpoint-taxonomy-for-cless]
McFadden, M., "Endpoint Taxonomy for CLESS", draft-
mcfadden-smart-endpoint-taxonomy-for-cless-00 (work in
progress), July 2019.
[I-D.nottingham-for-the-users]
Nottingham, M., "The Internet is for End Users", draft-
nottingham-for-the-users-09 (work in progress), July 2019.
[I-D.taddei-smart-cless-introduction]
Taddei, A., Wueest, C., Roundy, K., and D. Lazanski,
"Capabilities and Limitations of an Endpoint-only Security
Solution", draft-taddei-smart-cless-introduction-01 (work
in progress), July 2019.
[Kocher2019]
Kocher, P., Horn, J., Fogh, A., Genkin, D., Gruss, D.,
Haas, W., Hamburg, M., Lipp, M., Mangard, S., Prescher,
T., Schwarz, M., and Y. Yarom, "Spectre Attacks:
Exploiting Speculative Execution", 40th IEEE Symposium on
Security and Privacy (S&P'19) , 2019.
[LeakyBuckets]
Chickowski, E., "Leaky Buckets: 10 Worst Amazon S3
Breaches", Bitdefender blog,
https://businessinsights.bitdefender.com/
worst-amazon-breaches , 2018.
[Lipp2018]
Lipp, M., Schwarz, M., Gruss, D., Prescher, T., Haas, W.,
Fogh, A., Horn, J., Mangard, S., Kocher, P., Genkin, D.,
Yarom, Y., and M. Hamburg, "Meltdown: Reading Kernel
Memory from User Space", 27th USENIX Security Symposium
(USENIX Security 18) , 2018.
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[Mailbug] Englehardt, S., Han, J., and A. Narayanan, "I never signed
up for this! Privacy implications of email tracking",
Proceedings on Privacy Enhancing Technologies 2018.1
(2018): 109-126, https://www.degruyter.com/downloadpdf/j/
popets.2018.2018.issue-1/popets-2018-0006/
popets-2018-0006.pdf , 2018.
[MeltdownAndSpectre]
CISA, ., "Meltdown and Spectre Side-Channel Vulnerability
Guidance", Alert (TA18-004A),
https://www.us-cert.gov/ncas/alerts/TA18-004A , 2018.
[Passwords]
com, haveibeenpwned., "Pwned Passwords", Website
https://haveibeenpwned.com/Passwords , 2019.
[RFC1958] Carpenter, B., Ed., "Architectural Principles of the
Internet", RFC 1958, DOI 10.17487/RFC1958, June 1996,
<https://www.rfc-editor.org/info/rfc1958>.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552,
DOI 10.17487/RFC3552, July 2003,
<https://www.rfc-editor.org/info/rfc3552>.
[RFC3935] Alvestrand, H., "A Mission Statement for the IETF",
BCP 95, RFC 3935, DOI 10.17487/RFC3935, October 2004,
<https://www.rfc-editor.org/info/rfc3935>.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC6454] Barth, A., "The Web Origin Concept", RFC 6454,
DOI 10.17487/RFC6454, December 2011,
<https://www.rfc-editor.org/info/rfc6454>.
[RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support
Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480,
February 2012, <https://www.rfc-editor.org/info/rfc6480>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012,
<https://www.rfc-editor.org/info/rfc6749>.
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[RFC6797] Hodges, J., Jackson, C., and A. Barth, "HTTP Strict
Transport Security (HSTS)", RFC 6797,
DOI 10.17487/RFC6797, November 2012,
<https://www.rfc-editor.org/info/rfc6797>.
[RFC6819] Lodderstedt, T., Ed., McGloin, M., and P. Hunt, "OAuth 2.0
Threat Model and Security Considerations", RFC 6819,
DOI 10.17487/RFC6819, January 2013,
<https://www.rfc-editor.org/info/rfc6819>.
[RFC6962] Laurie, B., Langley, A., and E. Kasper, "Certificate
Transparency", RFC 6962, DOI 10.17487/RFC6962, June 2013,
<https://www.rfc-editor.org/info/rfc6962>.
[RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
Morris, J., Hansen, M., and R. Smith, "Privacy
Considerations for Internet Protocols", RFC 6973,
DOI 10.17487/RFC6973, July 2013,
<https://www.rfc-editor.org/info/rfc6973>.
[RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an
Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May
2014, <https://www.rfc-editor.org/info/rfc7258>.
[RFC7469] Evans, C., Palmer, C., and R. Sleevi, "Public Key Pinning
Extension for HTTP", RFC 7469, DOI 10.17487/RFC7469, April
2015, <https://www.rfc-editor.org/info/rfc7469>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/info/rfc7540>.
[RFC7817] Melnikov, A., "Updated Transport Layer Security (TLS)
Server Identity Check Procedure for Email-Related
Protocols", RFC 7817, DOI 10.17487/RFC7817, March 2016,
<https://www.rfc-editor.org/info/rfc7817>.
[RFC8240] Tschofenig, H. and S. Farrell, "Report from the Internet
of Things Software Update (IoTSU) Workshop 2016",
RFC 8240, DOI 10.17487/RFC8240, September 2017,
<https://www.rfc-editor.org/info/rfc8240>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
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[RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS
(DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018,
<https://www.rfc-editor.org/info/rfc8484>.
[RFC8546] Trammell, B. and M. Kuehlewind, "The Wire Image of a
Network Protocol", RFC 8546, DOI 10.17487/RFC8546, April
2019, <https://www.rfc-editor.org/info/rfc8546>.
[RFC8555] Barnes, R., Hoffman-Andrews, J., McCarney, D., and J.
Kasten, "Automatic Certificate Management Environment
(ACME)", RFC 8555, DOI 10.17487/RFC8555, March 2019,
<https://www.rfc-editor.org/info/rfc8555>.
[Saltzer] Saltzer, J., Reed, D., and D. Clark, "End-To-End Arguments
in System Design", ACM TOCS, Vol 2, Number 4, pp 277-288 ,
November 1984.
[Savage] Savage, S., "Modern Automotive Vulnerabilities: Causes,
Disclosures, and Outcomes", USENIX , 2016.
[SmartTV] Malkin, N., Bernd, J., Johnson, M., and S. Egelman, "What
Can't Data Be Used For? Privacy Expectations about Smart
TVs in the U.S.", European Workshop on Usable Security
(Euro USEC), https://www.ndss-symposium.org/wp-
content/uploads/2018/06/
eurousec2018_16_Malkin_paper.pdf" , 2018.
[StackEvo]
Trammell, B., Thomson, M., Howard, L., and T. Hardie,
"What Is an Endpoint?", Unpublished work,
https://github.com/stackevo/endpoint-draft/blob/master/
draft-trammell-whats-an-endpoint.md , 2017.
[Sybil] Viswanath, B., Post, A., Gummadi, K., and A. Mislove, "An
analysis of social network-based sybil defenses", ACM
SIGCOMM Computer Communication Review 41(4), 363-374,
https://conferences.sigcomm.org/sigcomm/2010/papers/
sigcomm/p363.pdf , 2011.
[TargetAttack]
Osborne, C., "How hackers stole millions of credit card
records from Target", ZDNET,
https://www.zdnet.com/article/how-hackers-stole-millions-
of-credit-card-records-from-target/ , 2014.
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[Toys] Chu, G., Apthorpe, N., and N. Feamster, "Security and
Privacy Analyses of Internet of Things Childrens' Toys",
IEEE Internet of Things Journal 6.1 (2019): 978-985,
https://arxiv.org/pdf/1805.02751.pdf , 2019.
[Tracking]
Ermakova, T., Fabian, B., Bender, B., and K. Klimek, "Web
Tracking-A Literature Review on the State of Research",
Proceedings of the 51st Hawaii International Conference on
System Sciences, https://scholarspace.manoa.hawaii.edu/
bitstream/10125/50485/paper0598.pdf , 2018.
[Troll] Stewart, L., Arif, A., and K. Starbird, "Examining trolls
and polarization with a retweet network", ACM Workshop on
Misinformation and Misbehavior Mining on the Web,
https://faculty.washington.edu/kstarbi/
examining-trolls-polarization.pdf , 2018.
[Unread] Obar, J. and A. Oeldorf, "The biggest lie on the
internet{:} Ignoring the privacy policies and terms of
service policies of social networking services",
Information, Communication and Society (2018): 1-20 ,
2018.
[Vpns] Khan, M., DeBlasio, J., Voelker, G., Snoeren, A., Kanich,
C., and N. Vallina, "An empirical analysis of the
commercial VPN ecosystem", ACM Internet Measurement
Conference 2018 (pp. 443-456),
https://eprints.networks.imdea.org/1886/1/
imc18-final198.pdf , 2018.
Appendix A. Acknowledgements
The authors would like to thank the IAB:
Alissa Cooper, Wes Hardaker, Ted Hardie, Christian Huitema, Zhenbin
Li, Erik Nordmark, Mark Nottingham, Melinda Shore, Jeff Tantsura,
Martin Thomson, Brian Trammel, Mirja Kuhlewind, and Colin Perkins.
The authors would also like to thank the participants of the IETF
SAAG meeting where this topic was discussed:
Harald Alvestrand, Roman Danyliw, Daniel Kahn Gilmore, Wes Hardaker,
Bret Jordan, Ben Kaduk, Dominique Lazanski, Eliot Lear, Lawrence
Lundblade, Kathleen Moriarty, Kirsty Paine, Eric Rescorla, Ali
Rezaki, Mohit Sethi, Ben Schwartz, Dave Thaler, Paul Turner, David
Waltemire, and Jeffrey Yaskin.
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The authors would also like to thank the participants of the IAB 2019
DEDR workshop:
Tuomas Aura, Vittorio Bertola, Carsten Bormann, Stephane Bortzmeyer,
Alissa Cooper, Stephen Farrell, Hannu Flinck, Carl Gahnberg, Phillip
Hallam-Baker, Ted Hardie, Paul Hoffman, Christian Huitema, Geoff
Huston, Konstantinos Komaitis, Mirja Kuhlewind, Dirk Kutscher,
Zhenbin Li, Julien Maisonneuve, John Mattson, Moritz Muller, Joerg
Ott, Lucas Pardue, Jim Reid, Jan-Frederik Rieckers, Mohit Sethi,
Melinda Shore, Jonne Soininen, Andrew Sullivan, and Brian Trammell.
The authors would also like to thank the participants of the November
2016 meeting at the IETF:
Carsten Bormann, Tommy C, Roman Danyliw, Christian Huitema, Ben
Kaduk, Dirk Kutscher, Dominique Lazanski, Eric Rescorla, Ali Rezaki,
Melinda Shore, Martin Thomson, and Robin Wilton ... (missing many
people... did we have minutes other than the list of actions?) ...
Finally, the authors would like to thank numerous other people for
insightful comments and discussions in this space.
Authors' Addresses
Jari Arkko
Ericsson
Email: jari.arkko@piuha.net
Stephen Farrell
Trinity College Dublin
Email: stephen.farrell@cs.tcd.ie
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