Coordinating Attack Response at Internet Scale 2 (CARIS2) Workshop Report
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Independent Submission                                       K. Moriarty
Request for Comments: 8953                  Center for Internet Security
Category: Informational                                    December 2020
ISSN: 2070-1721

   Coordinating Attack Response at Internet Scale 2 (CARIS2) Workshop
                                 Report

Abstract

   The Coordinating Attack Response at Internet Scale (CARIS) 2
   workshop, sponsored by the Internet Society, took place on 28
   February and 1 March 2019 in Cambridge, Massachusetts, USA.
   Participants spanned regional, national, international, and
   enterprise Computer Security Incident Response Teams (CSIRTs),
   operators, service providers, network and security operators,
   transport operators and researchers, incident response researchers,
   vendors, and participants from standards communities.  This workshop
   continued the work started at the first CARIS workshop, with a focus
   on scaling incident prevention and detection as the Internet industry
   moves to a stronger and a more ubiquitous deployment of session
   encryption.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This is a contribution to the RFC Series, independently of any other
   RFC stream.  The RFC Editor has chosen to publish this document at
   its discretion and makes no statement about its value for
   implementation or deployment.  Documents approved for publication by
   the RFC Editor are not candidates for any level of Internet Standard;
   see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8953.

Copyright Notice

   Copyright (c) 2020 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
   carefully, as they describe your rights and restrictions with respect
   to this document.

Table of Contents

   1.  Introduction
   2.  Accepted Papers
   3.  CARIS2 Goals
   4.  Workshop Collaboration
     4.1.  Breakout 1 Results: Standardization and Adoption
       4.1.1.  Wide Adoption
       4.1.2.  Limited Adoption
     4.2.  Breakout 2 Results: Preventative Protocols and Scaling
           Defense
     4.3.  Breakout 3 Results: Incident Response Coordination
     4.4.  Breakout 4 Results: Monitoring and Measurement
       4.4.1.  IP Address Reputation
       4.4.2.  Server Name Authentication Reputation C (SNARC)
       4.4.3.  Logging
       4.4.4.  Fingerprinting
     4.5.  Taxonomy and Gaps Session
   5.  Next Steps
   6.  Summary
   7.  Security Considerations
   8.  IANA Considerations
   9.  References
     9.1.  Informative References
   Acknowledgements
   Author's Address

1.  Introduction

   The Coordinating Attack Response at Internet Scale (CARIS) 2 workshop
   [CARISEvent], sponsored by the Internet Society, took place on 28
   February and 1 March 2019 in Cambridge, Massachusetts, USA.
   Participants spanned regional, national, international, and
   enterprise Computer Security Incident Response Teams (CSIRTs),
   operators, service providers, network and security operators,
   transport operators and researchers, incident response researchers,
   vendors, and participants from standards communities.  This workshop
   continued the work started at the first CARIS workshop [RFC8073],
   with a focus on scaling incident prevention and detection as the
   Internet industry moves to a stronger and a more ubiquitous
   deployment of session encryption.  Considering the related initiative
   to form a research group (Stopping Malware and Researching Threats
   [SMART]) in the Internet Research Task Force (IRTF), the focus on
   prevention included consideration of research opportunities to
   improve protocols and determine if there are ways to improve attack
   detection during the protocol design phase that could later influence
   protocol development in the IETF.  This is one way to think about
   scaling response, through prevention and allowing for new methods to
   evolve for detection in a post-encrypted world.  Although the
   proposed SMART Research Group has not yet progressed, the work to
   better scale incident response continues through the projects
   proposed at CARIS2 as well as in future CARIS workshops.

2.  Accepted Papers

   Researchers from around the world submitted position and research
   papers summarizing key aspects of their work to help form the shared
   content of the workshop.  The accepted papers may be found at
   [CARISEvent] and include:

   *  Visualizing Security Automation: Takeshi Takahashi, NICT, Japan

   *  Automating Severity Determination: Hideaki Kanehara, NICT, Japan

   *  OASIS's OpenC2: Draper and DoD

   *  Automated IoT Security: Oscar Garcia-Morchon and Thorsten Dahm

   *  Taxonomies and Gaps: Kirsty P., UK NCSC

   *  FIRST: Thomas Schreck, Siemens

   *  NetSecWarriors: Tim April, Akamai

   *  Measured Approaches to IPv6 Address Anonymization and Identity
      Association: Dave Plonka and Arthur Berger, Akamai

   The program committee worked to fill in the agenda with meaningful
   and complementary sessions to round out the theme and encourage
   collaboration to advance research toward the goals of the workshop.
   These sessions included:

   *  Manufacturer Usage Description (MUD) [RFC8520]: Eliot Lear, Cisco

   *  TF-CSIRT: Mirjam Kühne, RIPE NCC

   *  M2M Sharing Revolution: Scott Pinkerton, DoE ANL

   *  Comparing OpenC2 with existing efforts, e.g., I2NSF [I2NSF]: Chris
      Inacio

   *  Alternate Sharing and Mitigation Models: Kathleen Moriarty, Dell
      EMC

   The presentations provided interesting background to familiarize
   workshop attendees with current research work, challenges that must
   be addressed for forward progress, and opportunities to collaborate
   in the desire to better scale attack response and prevention.

3.  CARIS2 Goals

   The goal of each CARIS workshop has been to focus on the challenge of
   improving the overall security posture.  The approach has been to
   identify intrinsic or built-in protection capabilities for improved
   defense, automation, and scaling attack response through
   collaboration and improved architectural patterns.  It has been
   assumed that additional training will likely not address the lack of
   information security professionals to fill the job gap.  Currently,
   there is approximately a three-million-person deficit [deficit] for
   security professionals worldwide, and that is only expected to grow.
   In preparing for the workshop, the chair and program committee
   considered that this gap cannot be filled through training but
   requires measures to reduce the number of information security
   professionals needed through new architectures and research toward
   attack prevention.  CARIS2 was specifically focused on the industry
   shift toward the increased use of stronger session encryption
   (TLS 1.3 [RFC8446], QUIC [QUIC], tcpcrypt [RFC8548], etc.) and how
   prevention and detection can advance in this new paradigm.  As such,
   the goals for this workshop included:

   *  Scale attack response, including ways to improve prevention, as
      the Internet shifts to use of stronger and more ubiquitous
      encryption.

      -  Determine research opportunities

      -  Consider methods to improve protocols and provide guidance
         toward goal.  For instance, are there ways to build detection
         of threats into protocols, since they cannot be monitored on
         the wire in the future?

   *  Identify promising research ideas to seed a research agenda to
      input to the proposed IRTF SMART Research Group.

4.  Workshop Collaboration

   Both CARIS workshops brought together a set of individuals who had
   not previously collaborated toward the goals of scaling attack
   response.  This is important as the participants span various areas
   of Internet technology work, conduct research, provide a global
   perspective, have access to varying data sets and infrastructure, and
   are influential in their area of expertise.  The specific goals,
   contributions, and participants of the CARIS2 workshop were all
   considered in the design of the breakout sessions to both identify
   and advance research through collaboration.  The breakout sessions
   varied in format to keep attendees engaged and collaborating; some
   involved the full set of attendees while others utilized groups.

   The workshop focused on identifying potential areas for collaboration
   and advancing research.

   1.  Standardization and Adoption: identify widely adopted and
       pervasive standard protocols and data formats as well as those
       that failed.

   2.  Preventative Protocols and Scaling Defense: identify protocols to
       address automation at scale.

   3.  Incident Response Coordination: brainstorm what potential areas
       of research or future workshops could be held to improve on the
       scalability of incident response.

   4.  Monitoring and Measurement: brainstorm methods to perform
       monitoring and measurement with the heightened need and
       requirement to address privacy.

   5.  Taxonomy and Gaps: brainstorm a way forward for the proposed
       SMART Research Group.

4.1.  Breakout 1 Results: Standardization and Adoption

   This breakout session considered points raised in the preceding talks
   on hurdles for automating security controls, detection, and response;
   the teams presenting noted several challenges they still face today.
   The breakout session worked toward identifying standard protocols and
   data formats that succeeded in achieving adoption as well as several
   that failed or only achieved limited adoption.  The results from the
   evaluation were interesting and could aid in achieving greater
   adoption when new work areas are developed.  The following
   subsections detail the results.

4.1.1.  Wide Adoption

   The Transport Layer Security (TLS) protocol has replaced the Secure
   Sockets Layer (SSL) protocol.

   Observations: There was a clear need for session encryption at the
   transport layer to protect application data.  E-commerce was a
   driving force at the time with a downside to those who did not adopt.
   Other positive attributes that aided adoption were modular design,
   clean interfaces, and being first to market.

   The Simple Network Management Protocol (SNMP) enables configuration
   management of devices with extension points for private configuration
   and management settings.  SNMP is widely adopted and is only now,
   after decades, being replaced by a newer alternative, YANG (a data
   modeling language) that facilitates configuration management via the
   Network Configuration Protocol (NETCONF) or RESTCONF.  SNMP
   facilitated an answer to a needed problem set: configuration,
   telemetry, and network management.  Its development considered the
   connection between the user, vendor, and developers.  Challenges did
   surface for adoption from SNMPv1.1 to 1.2, as there was no compelling
   reason for adoption.  SNMPv3 gained adoption due to its resilience to
   attacks by providing protection through improved authentication and
   encryption.

   IP Flow Information Export (IPFIX) was identified as achieving wide
   adoption for several reasons.  The low cost of entry, wide vendor
   support, diverse user base, and wide set of use cases spanning
   multiple technology areas were some of the key drivers cited.

   X.509 was explored for its success in gaining adoption.  The solution
   being abstract from crypto, open, customizable, and extensible were
   some of the reasons cited for its successful adoption.  The team
   deemed it a good solution to a good problem and observed that
   government adoption aided its success.

4.1.2.  Limited Adoption

   Next, each team evaluated solutions that have not enjoyed wide
   adoption.

   Although Structured Threat Information eXpression (STIX) and the
   Incident Object Description Exchange Format (IODEF) are somewhat
   similar in their goals, the standards were selected for evaluation by
   two separate groups with some common findings.

   STIX has had limited adoption by the financial sector but no single,
   definitive end user.  The standard is still in development with the
   US government as the primary developer in partnership with OASIS.
   There is interest in using STIX to manage content, but users don't
   really care about what technology is used for the exchange.  The
   initial goals may not wind up matching the end result for STIX, as
   managing content may be the primary use case.

   IODEF was specified by National Research and Education Networks
   (NRENs) and Computer Security Incident Response Teams (CSIRTs) and
   formalized in the IETF [RFC7970].  The user is the security
   operations center (SOC).  While there are several implementations, it
   is not widely adopted.  In terms of exchange, users are more
   interested in indicators than full event information, and this
   applies to STIX as well.  Sharing and trust are additional hurdles as
   many are not willing to disclose information.

   DNS-Based Authentication of Named Entities (DANE) has DNSSEC as a
   dependency, which is a hurdle toward adoption (too many
   dependencies).  It has a roll-your-own adoption model, which is
   risky.  While there are some large pockets of adoption, there is
   still much work to do to gain widespread adoption.  A regulatory
   requirement gave rise to partial adoption in Germany, which naturally
   resulted in production of documentation written in German -- possibly
   giving rise to further adoption in German-speaking countries.  There
   has also been progress made in the Netherlands through the creation
   of a website: <internet.nl>.  The website allows you to test your
   website for a number of standards (IPv6, DNSSEC, DANE, etc.).
   <internet.nl> is a collaboration of industry organizations,
   companies, and the government in the Netherlands and is available for
   worldwide use.

   IP version 6 (IPv6) has struggled, and the expense of running a dual
   stack was one of the highest concerns on the list discussed in the
   workshop breakout.  The end user for IPv6 is everyone, and the
   breakout team considered it too ambiguous.  Too many new requirements
   have been added over its 20-year life.  The scope of necessary
   adoption is large with many peripheral devices.  Government
   requirements for support have helped somewhat with improved
   interoperability and adoption, but features like NAT being added to
   IPv4 slowed adoption.  With no new features being added to IPv4 and
   lessons learned, there's still a possibility for success.

4.2.  Breakout 2 Results: Preventative Protocols and Scaling Defense

   This breakout session followed the sessions on MUD, Protocol for
   Automated Vulnerability Assessment (PAVA), and Protocol for Automatic
   Security Configuration (PASC), which have themes of automation at
   scale.  MUD was designed for Internet of Things (IoT), and as such,
   scaling was a major consideration.  The PAVA and PASC work builds off
   of MUD and maintains some of the same themes.  This breakout session
   was focused on groups brainstorming preventative measures and
   enabling vendors to deploy mitigations.

   One group dove a bit deeper into MUD and layer 2 (L2) discovery.  MUD
   changes sets of filtering control management to the vendor or
   intermediary MUD vendors for a predictable platform that scales well.
   While the overall value of MUD is clear, the use of MUD and what
   traffic is expected for a particular device should be considered
   sensitive information, as it could be used to exploit a device.  MUD
   has an option of using L2 discovery to share MUD files.  L2
   discovery, like the Dynamic Host Configuration Protocol (DHCP), is
   not encrypted from the local client to the DHCP server at this point
   in time (there is some interest to correct this, but it hasn't
   received enough support yet).  As a result, it is possible to leak
   information and reveal data about the devices for which the MUD files
   would be applied.  This could multicast out information such as
   network characteristics, firmware versions, manufacturers, etc.
   There was some discussion on the use of 802.11 to improve connections
   [IEEE802.11].  Several participants from this group plan to research
   this further and identify options to prevent information leakage
   while achieving the stated goals of MUD.

   The next group discussed a proposal one of the participants had
   already begun developing, namely privacy for rendezvous service.  The
   basic idea was to encrypt Server Name Indication (SNI) using DNS to
   obtain public keys.  The suffix on server IPv6 would be unique to a
   TLS session (information missing).  The discussion on this proposal
   was fruitful, as the full set of attendees engaged, with special
   interest from the incident responders to be involved in early review
   cycles.  Incident responders are very interested to understand how
   protocols will change and to assess the overall impact of changes on
   privacy and security operations.  Even if there are no changes to the
   protocol proposals stemming from this review, the group discussion
   landed on this being a valuable exchange to understand early the
   impacts of changes for incident detection and mitigation, to devise
   new strategies, and to provide assessments on the impact of protocol
   changes on security in the round.

   The third group reported back on trust exchanges relying heavily on
   relationships between individuals.  They were concerned with scaling
   the trust model and finding ways to do that better.  The group dove
   deeper into this topic.

   The fourth group discussed useful data for incident responders.  This
   built on the first breakout session (Section 4.1).  The group
   determined that indicators of compromise (IoCs) are what most
   organizations and groups are able to successfully exchange.  Ideally,
   these would be fixed and programmable.  They discussed developing a
   richer format for sharing event threats.  When reporting back to the
   group, a successful solution used in the EU was mentioned: the
   Malware Information Sharing Platform (MISP) [MISP].  This will be
   considered in the review of existing efforts to determine if anything
   new is needed.

4.3.  Breakout 3 Results: Incident Response Coordination

   Incident response coordination currently does not scale.  This
   breakout session focused on brainstorming incident response and
   coordination, looking specifically at what works well for teams
   today, what is holding them back, and what risks loom ahead.  Output
   from this session could be used to generate research and to dive
   deeper in a dedicated workshop on these topics.

   Supporting:

   *  Trust between individuals in incident response teams

   *  Volume of strong signals and automated discovery

   *  Need to protect network as a forcing function

   *  Law and legal catalyst, motivator to stay on top

   *  Current efforts supported by profit and company interests, but
      those may shift

   *  Fear initially results in activity or in terms of the diagram
      used, a burst of wind, but eventually leads to complacency

   What creates drag:

   *  Lack of clear Key Performance Indicators (KPIs)

   *  Too many standards

   *  Potential for regional borders to impact data flows

   *  Ease of use for end users

   *  Speed to market without security considerations

   *  Legal framework slow to adapt

   *  Disconnect in actual/perceived risk

   *  Regulatory requirements preventing data sharing

   *  Lack of clarity in shared information

   *  Behind the problem/reactionary

   *  Lack of resources/participation

   *  Monoculture narrows focus

   Looming problems:

   *  Dynamic threat landscape

   *  Liability

   *  Vocabulary collision

   *  Lack of target/adversary clarity

   *  Bifurcation of Internet

   *  Government regulation

   *  Confusion around metrics

   *  Sensitivity of intelligence (trust)

   *  Lack of skilled analysts

   *  Lack of "fraud loss" data sharing

   *  Stakeholder/leader confusion

   *  Unknown impact of emerging technologies

   *  Overcentralization of the Internet

   *  New technologies and protocols

   *  Changes in application-layer configurations (e.g., browser
      resolvers)

4.4.  Breakout 4 Results: Monitoring and Measurement

   The fourth breakout session followed Dave Plonka's talk on IPv6
   aggregation to provide privacy for IPv6 sessions.  Essentially, IPv6
   provides additional capabilities for monitoring sessions end to end.
   Dave and his coauthor, Arthur Berger, primarily focus on measurement
   research but found a way to aggregate sessions to assist with
   maintaining user privacy.  If you can devise methods to perform
   management and measurement, or even perform security functions, while
   accommodating methods to protect privacy, a stronger result is
   likely.  This also precludes the need for additional privacy
   improvement work to defeat measurement objectives.

   This breakout session was focused on devising methods to perform
   monitoring and measurement, coupled with advancing privacy
   considerations.  The full group listed out options for protocols to
   explore and ranked them, with the four highest then explored by the
   breakout groups.  Groups agreed to work further on the proposed
   ideas.

4.4.1.  IP Address Reputation

   There is a need to understand address assignment and configuration
   for hosts and services, especially with IPv6 [PlonkaBergerCARIS2] in
   (1) sharing IP-address-related information to inform attack response
   efforts while still protecting the privacy of victims and possible
   attackers and (2) mitigating abuse by altering the treatment, e.g.,
   dropping or rate-limiting, of packets.  Currently, there is no
   database that analysts and researchers can consult to, for instance,
   determine the lifetimes of IPv6 addresses or the prefix length at
   which the address is expected to be stable over time.  The
   researchers propose either introducing a new database (compare
   PeeringDB) or extending existing databases (e.g., the regional
   Internet registries (RIRs)) to contain such information and allowing
   arbitrary queries.  The prefix information would either be provided
   by networks that are willing or based on measurement algorithms that
   reverse-engineer reasonable values based on Internet measurements
   [PlonkaBergerKIP].  In the former case, the incentive of networks to
   provide such information is to ensure that privacy of their users is
   respected and to limit collateral damage caused by access control
   lists affecting more of that network's addresses than necessary,
   e.g., in the face of abuse.  This is an early idea; Dave Plonka is
   the lead contact for those interested in helping to develop this
   further.

4.4.2.  Server Name Authentication Reputation C (SNARC)

   SNARC is a mechanism to assign value to trust indicators, used to
   make decisions about good or bad actors.  The mechanism would be able
   to distinguish between client and server connections and would be
   human readable.  In addition, it builds on zero trust networking and
   avoids consolidation, thus supporting legitimate new players.  SNARC
   has a similar theme to the IP reputation/BGP ranking idea mentioned
   above.  SNARC is not currently defined by an RFC; however, such an
   RFC would help customers and design teams on existing solutions.  The
   group plans to research visual aspects and underlying principles as
   they begin work on this idea.  They plan to begin work in several
   stages, researching "trust" indicators, "trust" value calculations,
   and research actions to apply to "trust".  The overarching goal is to
   address blind trust, one of the challenges identified with
   information/incident exchanges.  Trent Adams is the lead contact for
   those interested in working with this team.

4.4.3.  Logging

   The group presented the possibility of injecting logging capabilities
   at compile time for applications, resulting in a more consistent set
   of logs, covering an agreed set of conditions.  Using a log-injecting
   compiler would increase logging for those applications and improve
   the uniformity of logged activity.  Increasing logging capabilities
   at the endpoint is necessary as the shift toward increased use of
   encrypted transport continues.  Nalini Elkins is the lead contact for
   those interested in developing this further.

4.4.4.  Fingerprinting

   Fingerprinting has been used for numerous applications on the Web,
   including security, and will become of increasing importance with the
   deployment of stronger encryption.  Fingerprinting provides a method
   to identify traffic without using decryption.  The group discussed
   privacy considerations and balancing how you achieve the security
   benefits (identifying malicious traffic, information leakage, threat
   indicators, etc.).  They are interested in deriving methods to
   validate the authenticity without identifying the source of traffic.
   They are also concerned with scaling issues.  William Weinstein is
   the lead contact for those interested in working with this team.

4.5.  Taxonomy and Gaps Session

   At the start of the second day of the workshop, Kirsty Paine and
   Mirjam Kühne prepared (and Kirsty led) a workshop-style session to
   discuss taxonomies used in incident response, attacks, and threat
   detection, comparing solutions and identifying gaps.  The primary
   objective was to determine a path forward by selecting the language
   to be used in the proposed SMART Research Group.  Several taxonomies
   were presented for review and discussion.  The topic remains open,
   but the following key points were highlighted by participants:

   *  A single taxonomy might not be the way to go, because which
      taxonomy you use depends on what problem you are trying to solve,
      e.g., attribution of the attack, mitigation steps, technical
      features, or organizational impact measurements.

   *  A tool to map between taxonomies should be automated, as there are
      requirements within groups or nations to use specific taxonomies.

   *  The level of detail needed for reporting to management and for the
      analyst investigating the incident can be very different.  At the
      workshop, one attendee mentioned that, for management reporting,
      they only use 8 categories to lighten the load on analysts,
      whereas some of the taxonomies contain 52 categories.

   *  How you plan to use the taxonomy matters and may vary between use
      cases.  Take, for instance, sharing data with external entities
      versus internal only.  The taxonomy selected depends on what you
      plan to do with it.  Some stated a need for attribute-based
      dynamic anthologies as opposed to rigid taxonomies used by others.
      A rigid taxonomy did not work for many from feedback in the
      session.

   *  [RFC4949] was briefly discussed as a possibility; however, there
      is a clear need to update terminology in this publication around
      this space in particular.  This is likely to be raised in the
      Security Area Advisory Group (SAAG) during the open mic session,
      hopefully with proposed new definitions to demonstrate the issue
      and evolution of terms over time.

   *  Within a taxonomy, prioritization matters to understand the impact
      of threats or an attack.  How do you map that between differing
      taxonomies?  What is the problem to be solved, and what tooling is
      required?

   *  Attack attribution had varying degrees of interest.  Some felt the
      public sector cared more about attribution, not about individuals.
      They were interested in possible motivations behind an attack and
      determining if there were other likely victims based on these
      motivations.  Understanding if the source was an individual actor,
      organized crime, or a nation state mattered.

   The result of this discussion was not to narrow down to one taxonomy
   but to think about mappings between taxonomies and the use cases for
   exchanging or sharing information, eventually giving rise to a common
   method to discuss threats and attacks.  Researchers need a common
   vocabulary, not necessarily a common taxonomy.

5.  Next Steps

   The next steps from the CARIS2 workshop are twofold:

   1.  The research initiatives spawned from the second CARIS workshop
       require further exploration and development.  Fostering this
       development and creating communities around each proposed project
       is the first step, with reports back out to the SMART mailing
       list.

   2.  The second initiative will be planning for the next CARIS
       workshop.

6.  Summary

   When wrapping up the workshop, we reviewed the list of agreed
   projects to get a feel for actual interest as a follow up.  Through
   the course of the two-day workshop, a larger set of potential
   research items had been generated, and this gave participants a
   chance to reassess commitments to better have them match expected
   outcomes.  The highest ranking projects in terms of interest to drive
   the ideas forward included the following:

   *  Traffic fingerprinting

   *  SNARC

   *  Attack coordination solutions and automated security

   *  Cryptographic rendezvous

   *  L2 discovery

7.  Security Considerations

   There are no security considerations, as this is an informational
   workshop summary report.

8.  IANA Considerations

   This document has no IANA actions.

9.  References

9.1.  Informative References

   [CARISEvent]
              Internet Society, "CARIS2: Coordinating Attack Response at
              Internet Scale", February 2019,
              <https://www.internetsociety.org/events/caris2>.

   [deficit]  Morgan, S., "Cybersecurity Talent Crunch To Create 3.5
              Million Unfilled Jobs Globally By 2021", October 2019,
              <https://cybersecurityventures.com/jobs/>.

   [I2NSF]    IETF, "Interface to Network Security Functions (i2nsf)",
              <https://datatracker.ietf.org/wg/i2nsf/about>.

   [IEEE802.11]
              IEEE, "IEEE 802.11 WIRELESS LOCAL AREA NETWORKS",
              <https://www.ieee802.org/11/>.

   [MISP]     MISP, "Malware Information Sharing Platform",
              <https://www.misp-project.org/>.

   [PlonkaBergerCARIS2]
              Plonka, D. and A. Berger, "Measured Approaches to IPv6
              Address Anonymization and Identity Association", CARIS2
              Paper Submission, March 2019,
              <https://www.internetsociety.org/events/caris2>.

   [PlonkaBergerKIP]
              Plonka, D. and A. Berger, "kIP: a Measured Approach to
              IPv6 Address Anonymization", July 2017,
              <https://arxiv.org/abs/1707.03900>.

   [QUIC]     Iyengar, J. and M. Thomson, "QUIC: A UDP-Based Multiplexed
              and Secure Transport", Work in Progress, Internet-Draft,
              draft-ietf-quic-transport-33, 13 December 2020,
              <https://tools.ietf.org/html/draft-ietf-quic-transport-
              33>.

   [RFC4949]  Shirey, R., "Internet Security Glossary, Version 2",
              FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
              <https://www.rfc-editor.org/info/rfc4949>.

   [RFC7970]  Danyliw, R., "The Incident Object Description Exchange
              Format Version 2", RFC 7970, DOI 10.17487/RFC7970,
              November 2016, <https://www.rfc-editor.org/info/rfc7970>.

   [RFC8073]  Moriarty, K. and M. Ford, "Coordinating Attack Response at
              Internet Scale (CARIS) Workshop Report", RFC 8073,
              DOI 10.17487/RFC8073, March 2017,
              <https://www.rfc-editor.org/info/rfc8073>.

   [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>.

   [RFC8520]  Lear, E., Droms, R., and D. Romascanu, "Manufacturer Usage
              Description Specification", RFC 8520,
              DOI 10.17487/RFC8520, March 2019,
              <https://www.rfc-editor.org/info/rfc8520>.

   [RFC8548]  Bittau, A., Giffin, D., Handley, M., Mazieres, D., Slack,
              Q., and E. Smith, "Cryptographic Protection of TCP Streams
              (tcpcrypt)", RFC 8548, DOI 10.17487/RFC8548, May 2019,
              <https://www.rfc-editor.org/info/rfc8548>.

   [SMART]    IRTF, "Stopping Malware and Researching Threats (smart)",
              <https://datatracker.ietf.org/group/smart/about/>.

Acknowledgements

   Thank you to each of the CARIS2 workshop participants who brought
   their ideas, energy, and willingness to collaborate to advance attack
   response at Internet scale.

   A big thank you to each member of the program committee for your
   review of program materials, papers, and guidance on the workshop
   format: Mat Ford (Internet Society, UK); Jamie Gillespie (APNIC, AU);
   Chris Inacio (CERT/CC, US); Mirja Kühlewind (ETH Zurich, CH); Mirjam
   Kühne (RIPE NCC, NL); Carlos Martinez (LACNIC, UY); Kathleen
   M. Moriarty, Chair (Dell EMC); Kirsty Paine (NCSC, UK); and Takeshi
   Takahashi (NICT, JP).

   Thank you to Megan Hyland (Dell EMC) for her review and guidance on
   the format of breakout sessions and tools to enable successful
   collaboration.

   Thank you to the minute takers, Akashaya Khare and Thinh Nguyen (Dell
   EMC OCTO Cambridge Dojo team).

Author's Address

   Kathleen M. Moriarty
   Center for Internet Security
   31 Tech Valley Drive
   East Greenbush, NY 12061
   United States of America

   Email: kathleen.moriarty.ietf@gmail.com