draft-ietf-repute-email-identifiers-10.txt   rfc7073.txt 
REPUTE Working Group N. Borenstein Internet Engineering Task Force (IETF) N. Borenstein
Internet-Draft Mimecast Request for Comments: 7073 Mimecast
Intended status: Standards Track M. Kucherawy Category: Standards Track M. Kucherawy
Expires: March 16, 2014 September 12, 2013 ISSN: 2070-1721 November 2013
A Reputation Response Set for Email Identifiers A Reputation Response Set for Email Identifiers
draft-ietf-repute-email-identifiers-10
Abstract Abstract
This document defines a response set for describing assertions a This document defines a response set for describing assertions a
reputation service provider can make about email identifers, for use reputation service provider can make about email identifiers, for use
in generating reputons. in generating reputons.
Status of this Memo 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 This is an Internet Standards Track document.
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
This Internet-Draft will expire on March 16, 2014. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7073.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction ....................................................2
2. Terminology and Definitions . . . . . . . . . . . . . . . . . . 3 2. Terminology and Definitions .....................................2
2.1. Key Words . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Key Words ..................................................2
2.2. Email Definitions . . . . . . . . . . . . . . . . . . . . . 3 2.2. Email Definitions ..........................................2
2.3. Other Definitions . . . . . . . . . . . . . . . . . . . . . 3 2.3. Other Definitions ..........................................3
3. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Discussion ......................................................3
3.1. Assertions . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Assertions .................................................3
3.2. Response Set Extensions . . . . . . . . . . . . . . . . . . 4 3.2. Response Set Extensions ....................................4
3.3. Identifiers . . . . . . . . . . . . . . . . . . . . . . . . 5 3.3. Identifiers ................................................4
3.4. Query Extensions . . . . . . . . . . . . . . . . . . . . . 6 3.4. Query Extensions ...........................................5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 4. IANA Considerations .............................................5
4.1. Registration of 'email-id' Reputation Application . . . . . 6 4.1. Registration of 'email-id' Reputation Application ..........5
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 5. Security Considerations .........................................6
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6. References ......................................................7
6.1. Normative References . . . . . . . . . . . . . . . . . . . 7 6.1. Normative References .......................................7
6.2. Informative References . . . . . . . . . . . . . . . . . . 8 6.2. Informative References .....................................7
Appendix A. Positive vs. Negative Assertions . . . . . . . . . . . 8 Appendix A. Positive vs. Negative Assertions .......................8
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . . 8 Appendix B. Acknowledgments ........................................8
Appendix C. Public Discussion . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction 1. Introduction
This document specifies a response set for describing reputation of This document specifies a response set for describing the reputation
an email identifier. A "response set" in this context is defined in of an email identifier. A "response set" in this context is defined
[I-D.REPUTE-MODEL] and is used to describe assertions a reputation in [RFC7070] and is used to describe assertions a reputation service
service provider can make about email identifiers as well as meta- provider can make about email identifiers as well as metadata that
data that can be included in such a reply beyond the base set can be included in such a reply beyond the base set specified there.
specified there.
An atomic reputation response is called a "reputon", defined in An atomic reputation response is called a "reputon", defined in
[I-D.REPUTE-MEDIA-TYPE]. That document also defines a media type to [RFC7071]. That document also defines a media type to contain a
contain a reputon for transport, and also creates a registry for reputon for transport, and creates a registry for reputation
reputation applications and the interesting parameters of each. applications and the interesting parameters of each.
2. Terminology and Definitions 2. Terminology and Definitions
This section defines terms used in the rest of the document. This section defines terms used in the rest of the document.
2.1. Key Words 2.1. Key Words
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [KEYWORDS]. document are to be interpreted as described in [KEYWORDS].
2.2. Email Definitions 2.2. Email Definitions
Commonly used definitions describing entities in the email Commonly used definitions describing entities in the email
architecture are defined and discussed in [EMAIL-ARCH]. architecture are defined and discussed in [EMAIL-ARCH].
2.3. Other Definitions 2.3. Other Definitions
Other terms of importance in this document are defined in Other terms of importance in this document are defined in [RFC7070],
[I-D.REPUTE-MODEL], the base document for the reputation services the base document for the reputation services work.
work.
3. Discussion 3. Discussion
The expression of reputation about an email identifier requires The expression of reputation about an email identifier requires
extensions of the base set defined in [I-D.REPUTE-MODEL]. This extensions of the base set defined in [RFC7070]. This document
document defines and registers some common assertions about an entity defines and registers some common assertions about an entity found in
found in a piece of [MAIL]. a piece of [MAIL].
3.1. Assertions 3.1. Assertions
The "email-id" reputation application recognizes the following The "email-id" reputation application recognizes the following
assertions: assertions:
abusive: The subject identifier is associated with sending or abusive: The subject identifier is associated with sending or
handling email of a personally abusive, threatening, or otherwise handling email of a personally abusive, threatening, or otherwise
harassing nature. harassing nature
fraud: The subject identifier is associated with sending or handling fraud: The subject identifier is associated with the sending or
of fraudulent email, such as "phishing" (some good discussion on handling of fraudulent email, such as "phishing" (some good
this topic can be found in [IODEF-PHISHING]) discussion on this topic can be found in [IODEF-PHISHING])
invalid-recipients: The subject identifier is associated with invalid-recipients: The subject identifier is associated with
delivery attempts to nonexistent recipients delivery attempts to nonexistent recipients
malware: The subject identifier is associated with the sending or malware: The subject identifier is associated with the sending or
handling of malware via email handling of malware via email
spam: The subject identifier is associated with sending or handling spam: The subject identifier is associated with the sending or
of unwanted bulk email handling of unwanted bulk email
For all assertions, the "rating" scale is linear: A value of 0.0 For all assertions, the "rating" scale is linear: a value of 0.0
means there is no data to support the assertion, a value of 1.0 means means there is no data to support the assertion, a value of 1.0 means
all accumulated data support the assertion, and the intervening all accumulated data support the assertion, and the intervening
values have a linear relationship (i.e., a score of "x" is twice as values have a linear relationship (i.e., a score of "x" is twice as
strong of an assertion as a value of "x/2"). strong of an assertion as a value of "x/2").
3.2. Response Set Extensions 3.2. Response Set Extensions
The "email-id" reputation application recognizes the following The "email-id" reputation application recognizes the following
OPTIONAL extensions to the basic response set defined in OPTIONAL extensions to the basic response set defined in [RFC7071]:
[I-D.REPUTE-MEDIA-TYPE]:
email-id-identity: A token indicating the source of the identifier; email-id-identity: A token indicating the source of the identifier;
that is, where the subject identifier was found in the message. that is, where the subject identifier was found in the message.
This MUST be one of: This MUST be one of:
dkim: The signing domain, i.e. the value of the "d=" tag, found dkim: The signing domain, i.e., the value of the "d=" tag, found
on a valid [DKIM] signature in the message on a valid DomainKeys Identified Mail [DKIM] signature in
the message
ipv4: The IPv4 address of the client ipv4: The IPv4 address of the client
ipv6: The IPv6 address of the client ipv6: The IPv6 address of the client
rfc5321.helo: The RFC5321.Helo value used by the (see [SMTP]) rfc5321.helo: The RFC5321.HELO value used by the client (see
client [SMTP])
rfc5321.mailfrom: The RFC5321.MailFrom value of the envelope of rfc5321.mailfrom: The RFC5321.MailFrom value of the envelope of
the message (see [SMTP]) the message (see [SMTP])
rfc5322.from: The RFC5322.From field of the message (see [MAIL]) rfc5322.from: The RFC5322.From field of the message (see [MAIL])
spf: The domain name portion of the identifier (RFC5321.MailFrom spf: The domain name portion of the identifier (RFC5321.MailFrom
or RFC5321.Helo) verified by [SPF] or RFC5321.HELO) verified by [SPF]
sources: A token relating a count of the number of sources of data sources: A token relating a count of the number of sources of data
that contributed to the reported reputation. This is in contrast that contributed to the reported reputation. This is in contrast
to the "sample-size" parameter, which indicates the total number to the "sample-size" parameter, which indicates the total number
of reports across all reporting sources. of reports across all reporting sources.
A reply that does not contain the "identity" or "sources" extensions A reply that does not contain the "identity" or "sources" extensions
is making a non-specific statement about how the reputation returned is making a non-specific statement about how the reputation returned
was developed. A client can use or ignore such a reply at its was developed. A client can use or ignore such a reply at its
discretion. discretion.
skipping to change at page 5, line 40 skipping to change at page 5, line 15
The purpose of including the identity in the reply is to expose to The purpose of including the identity in the reply is to expose to
the client the context in which the identifier was extracted from the the client the context in which the identifier was extracted from the
message under evaluation. In particular, several of the items listed message under evaluation. In particular, several of the items listed
are extracted verbatim from the message and have not been subjected are extracted verbatim from the message and have not been subjected
to any kind of validation, while a domain name present in a valid to any kind of validation, while a domain name present in a valid
DKIM signature has some more reliable semantics associated with it. DKIM signature has some more reliable semantics associated with it.
Computing or using reputation information about unauthenticated Computing or using reputation information about unauthenticated
identifiers has substantially reduced value, but can sometimes be identifiers has substantially reduced value, but can sometimes be
useful when combined. For example, a reply that indicates a message useful when combined. For example, a reply that indicates a message
contained one of these low-value identifiers with a high "spam" contained one of these low-value identifiers with a high "spam"
rating might not be worthy of notice, but a reply indicating a rating might not be worthy of notice, but a reply that indicates a
message contained several of them could be grounds for suspicion. message contained several of them could be grounds for suspicion.
A client interested in checking these weaker identifiers would issue A client interested in checking these weaker identifiers would issue
a query about each of them using the same assertion (e.g., "spam"), a query about each of them using the same assertion (e.g., "spam"),
and then collate the results to determine which ones and how many of and then collate the results to determine which ones and how many of
them came back with ratings indicating content of concern, and take them came back with ratings indicating content of concern, and take
action accordingly. For stronger identifiers, decisions can action accordingly. For stronger identifiers, decisions can
typically be made based on a few or even just one of them. typically be made based on a few or even just one of them.
3.4. Query Extensions 3.4. Query Extensions
skipping to change at page 6, line 20 skipping to change at page 5, line 40
Section 3.2. Section 3.2.
4. IANA Considerations 4. IANA Considerations
This memo presents one action for IANA, namely the registration of This memo presents one action for IANA, namely the registration of
the reputation application "email-id". the reputation application "email-id".
4.1. Registration of 'email-id' Reputation Application 4.1. Registration of 'email-id' Reputation Application
This section registers the "email-id" reputation application, as per This section registers the "email-id" reputation application, as per
the IANA Considerations section of [I-D.REPUTE-MEDIA-TYPE]. The the IANA Considerations section of [RFC7071]. The registration
registration parameters are as folows: parameters are as follows:
o Application name: email-id o Application symbolic name: email-id
o Short description: Evaluates DNS domain names or IP addresses o Short description: Evaluates DNS domain names or IP addresses
found in email identifiers found in email identifiers
o Defining document: [this document] o Defining document: [RFC7073]
o Status: current o Status: current
o Subject: A string appropriate to the identifier of interest (see o Subject: A string appropriate to the identifier of interest (see
Section 3.2 of this document) Section 3.2 of this document)
o Application-specific query parameters: o Application-specific query parameters:
identity: (current) as defined in Section 3.4 of this document identity: (current) as defined in Section 3.4 of this document
o Application-specific assertions: o Application-specific assertions:
abusive: (current) as defined in Section 3.1 of this document abusive: (current) as defined in Section 3.1 of this document
skipping to change at page 6, line 46 skipping to change at page 6, line 18
identity: (current) as defined in Section 3.4 of this document identity: (current) as defined in Section 3.4 of this document
o Application-specific assertions: o Application-specific assertions:
abusive: (current) as defined in Section 3.1 of this document abusive: (current) as defined in Section 3.1 of this document
fraud: (current) as defined in Section 3.1 of this document fraud: (current) as defined in Section 3.1 of this document
invalid-recipients: (current) as defined in Section 3.1 of this invalid-recipients: (current) as defined in Section 3.1 of this
document document
malware: (current) as defined in Section 3.1 of this document malware: (current) as defined in Section 3.1 of this document
spam: (current) as defined in Section 3.1 of this document
spam: (current) as defined in Section 3.1 of this document
o Application-specific response set extensions: o Application-specific response set extensions:
identity: (current) as defined in Section 3.2 of this document identity: (current) as defined in Section 3.2 of this document
5. Security Considerations 5. Security Considerations
This document is primarily an IANA action and doesn't describe any This document is primarily an IANA action and doesn't describe any
protocols or protocol elements that might introduce new security protocols or protocol elements that might introduce new security
concerns. concerns.
Security considerations relevant to email and email authentication Security considerations relevant to email and email authentication
can be found in most of the documents listed in the References can be found in most of the documents listed in the References
sections below. Information specific to use of reputation services sections below. Information specific to use of reputation services
can be found in [I-D.REPUTE-CONSIDERATIONS]. can be found in [CONSIDERATIONS].
6. References 6. References
6.1. Normative References 6.1. Normative References
[DKIM] Crocker, D., Ed., Hansen, T., Ed., and M. Kucherawy, Ed., [DKIM] Crocker, D., Ed., Hansen, T., Ed., and M. Kucherawy, Ed.,
"DomainKeys Identified Mail (DKIM) Signatures", RFC 6376, "DomainKeys Identified Mail (DKIM) Signatures", STD 76,
September 2011. RFC 6376, September 2011.
[EMAIL-ARCH] [EMAIL-ARCH]
Crocker, D., "Internet Mail Architecture", RFC 5598, Crocker, D., "Internet Mail Architecture", RFC 5598, July
July 2009. 2009.
[I-D.REPUTE-MEDIA-TYPE] [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Borenstein, N. and M. Kucherawy, "A Media Type for Requirement Levels", BCP 14, RFC 2119, March 1997.
Reputation Interchange", draft-ietf-repute-media-type
(work in progress), November 2012.
[I-D.REPUTE-MODEL] [RFC7070] Borenstein, N., Kucherawy, M., and A. Sullivan, "An
Borenstein, N. and M. Kucherawy, "A Model for Reputation Architecture for Reputation Reporting", RFC 7070, November
Reporting", draft-ietf-repute-model (work in progress), 2013.
November 2012.
[KEYWORDS] [RFC7071] Borenstein, N. and M. Kucherawy, "A Media Type for
Bradner, S., "Key words for use in RFCs to Indicate Reputation Interchange", RFC 7071, November 2013.
Requirement Levels", BCP 14, RFC 2119, March 1997.
[SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, [SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
October 2008. October 2008.
[SPF] Wong, M. and W. Schlitt, "Sender Policy Framework (SPF) [SPF] Wong, M. and W. Schlitt, "Sender Policy Framework (SPF)
for Authorizing Use of Domains in E-Mail, Version 1", for Authorizing Use of Domains in E-Mail, Version 1", RFC
RFC 4408, April 2006. 4408, April 2006.
6.2. Informative References 6.2. Informative References
[I-D.REPUTE-CONSIDERATIONS] [CONSIDERATIONS]
Kucherawy, M., "Operational Considerations Regarding Kucherawy, M., "Operational Considerations Regarding
Reputation Services", draft-ietf-repute-considerations Reputation Services", Work in Progress, May 2013.
(work in progress), November 2012.
[IODEF-PHISHING] [IODEF-PHISHING]
Cain, P. and D. Jevans, "Extensions to the IODEF-Document Cain, P. and D. Jevans, "Extensions to the IODEF-Document
Class for Reporting Phishing", RFC 5901, July 2010. Class for Reporting Phishing", RFC 5901, July 2010.
[MAIL] Resnick, P., Ed., "Internet Message Format", RFC 5322, [MAIL] Resnick, P., Ed., "Internet Message Format", RFC 5322,
October 2008. October 2008.
Appendix A. Positive vs. Negative Assertions Appendix A. Positive vs. Negative Assertions
[I-D.REPUTE-CONSIDERATIONS] some current theories about reputation, [CONSIDERATIONS] some current theories about reputation, namely that
namely that it is possibly more impactful to develop positive it will possibly have more impact to develop positive reputations and
reputations and focus on giving preferential treatment to content or focus on giving preferential treatment to content or sources that
sources that earn those. However, the assertions defined in this earn those. However, the assertions defined in this document are all
document are all clearly negative in nature. clearly negative in nature.
In effect, this document is recording current use of reputation and In effect, this document is recording current use of reputation and
of this framework in particular. It is expected that, in the future, of this framework in particular. It is expected that, in the future,
the application being registered here will be augmented, and other the application being registered here will be augmented, and other
applications registered, that focus more on positive assertions applications registered, that focus more on positive assertions
rather than negative ones. rather than negative ones.
Appendix B. Acknowledgments Appendix B. Acknowledgments
The authors wish to acknowledge the contributions of the following to The authors wish to acknowledge the contributions of the following to
this specification: Scott Hollenbeck, Scott Kitterman, Peter Koch, this specification: Scott Hollenbeck, Scott Kitterman, Peter Koch,
John Levine, Danny McPherson, S. Moonesamy, Doug Otis, and David F. John Levine, Danny McPherson, S. Moonesamy, Doug Otis, and David F.
Skoll. Skoll.
Appendix C. Public Discussion
Public discussion of this suite of memos takes place on the
domainrep@ietf.org mailing list. See
https://www.ietf.org/mailman/listinfo/domainrep.
Authors' Addresses Authors' Addresses
Nathaniel Borenstein Nathaniel Borenstein
Mimecast Mimecast
203 Crescent St., Suite 303 203 Crescent St., Suite 303
Waltham, MA 02453 Waltham, MA 02453
USA USA
Phone: +1 781 996 5340 Phone: +1 781 996 5340
Email: nsb@guppylake.com EMail: nsb@guppylake.com
Murray S. Kucherawy Murray S. Kucherawy
270 Upland Drive 270 Upland Drive
San Francisco, CA 94127 San Francisco, CA 94127
USA USA
Email: superuser@gmail.com EMail: superuser@gmail.com
 End of changes. 43 change blocks. 
112 lines changed or deleted 93 lines changed or added

This html diff was produced by rfcdiff 1.41. The latest version is available from http://tools.ietf.org/tools/rfcdiff/