draft-ietf-repute-email-identifiers-09.txt   draft-ietf-repute-email-identifiers-10.txt 
REPUTE Working Group N. Borenstein REPUTE Working Group N. Borenstein
Internet-Draft Mimecast Internet-Draft Mimecast
Intended status: Standards Track M. Kucherawy Intended status: Standards Track M. Kucherawy
Expires: March 2, 2014 August 29, 2013 Expires: March 16, 2014 September 12, 2013
A Reputation Response Set for Email Identifiers A Reputation Response Set for Email Identifiers
draft-ietf-repute-email-identifiers-09 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 identifers, 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 This Internet-Draft is submitted in full conformance with the
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 2, 2014. This Internet-Draft will expire on March 16, 2014.
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
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology and Definitions . . . . . . . . . . . . . . . . . . 3 2. Terminology and Definitions . . . . . . . . . . . . . . . . . . 3
2.1. Key Words . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Key Words . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Email Definitions . . . . . . . . . . . . . . . . . . . . . 3 2.2. Email Definitions . . . . . . . . . . . . . . . . . . . . . 3
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. Query Extensions . . . . . . . . . . . . . . . . . . . . . 5 3.3. Identifiers . . . . . . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 3.4. Query Extensions . . . . . . . . . . . . . . . . . . . . . 6
4.1. Registration of 'email-id' Reputation Application . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 4.1. Registration of 'email-id' Reputation Application . . . . . 6
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
6.1. Normative References . . . . . . . . . . . . . . . . . . . 6 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6.2. Informative References . . . . . . . . . . . . . . . . . . 7 6.1. Normative References . . . . . . . . . . . . . . . . . . . 7
Appendix A. Positive vs. Negative Assertions . . . . . . . . . . . 7 6.2. Informative References . . . . . . . . . . . . . . . . . . 8
Appendix A. Positive vs. Negative Assertions . . . . . . . . . . . 8
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . . 8 Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . . 8
Appendix C. Public Discussion . . . . . . . . . . . . . . . . . . 8 Appendix C. Public Discussion . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 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 reputation of
an email identifier. A "response set" in this context is defined in an email identifier. A "response set" in this context is defined in
[I-D.REPUTE-MODEL] and is used to describe assertions a reputation [I-D.REPUTE-MODEL] and is used to describe assertions a reputation
service provider can make about email identifiers as well as meta- service provider can make about email identifiers as well as meta-
data that can be included in such a reply beyond the base set data that can be included in such a reply beyond the base set
specified there. specified there.
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extensions of the base set defined in [I-D.REPUTE-MODEL]. This extensions of the base set defined in [I-D.REPUTE-MODEL]. This
document defines and registers some common assertions about an entity document defines and registers some common assertions about an entity
found in a piece of [MAIL]. found in 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 handling email of a personally abusive, threatening, or otherwise
otherwise harassing nature. harassing nature.
fraud: The subject identifier is associated with sending or handling fraud: The subject identifier is associated with sending or handling
of fraudulent email, such as "phishing" (some good discussion on of fraudulent email, such as "phishing" (some good discussion on
this topic can be found in [IODEF-PHISHING]) 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
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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
[I-D.REPUTE-MEDIA-TYPE]: [I-D.REPUTE-MEDIA-TYPE]:
identity: A token indicating the source of the identifier; that is, email-id-identity: A token indicating the source of the identifier;
where the subject identifier was found in the message. This MUST that is, where the subject identifier was found in the message.
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 [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 (see [SMTP])
client client
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.
3.3. Query Extensions 3.3. Identifiers
In evaluating an email message on the basis of reputation, there can
be more than one identifier in the message needing to be validated.
For example, a message may have different email addresses in the
RFC5321.MailFrom parameter and the RFC5322.From header field. The
RFC5321.Helo identifier will obviously be different. Consequently,
the software evaluating the email message may need to query for the
reputation of more than one identifier.
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
message under evaluation. In particular, several of the items listed
are extracted verbatim from the message and have not been subjected
to any kind of validation, while a domain name present in a valid
DKIM signature has some more reliable semantics associated with it.
Computing or using reputation information about unauthenticated
identifiers has substantially reduced value, but can sometimes be
useful when combined. For example, a reply that indicates a message
contained one of these low-value identifiers with a high "spam"
rating might not be worthy of notice, but a reply indicating a
message contained several of them could be grounds for suspicion.
A client interested in checking these weaker identifiers would issue
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
them came back with ratings indicating content of concern, and take
action accordingly. For stronger identifiers, decisions can
typically be made based on a few or even just one of them.
3.4. Query Extensions
A query within this application can include the OPTIONAL query A query within this application can include the OPTIONAL query
parameter "identity" to indicate which specific identity is of parameter "identity" to indicate which specific identity is of
interest to the query. Legal values are the same as those listed in interest to the query. Legal values are the same as those listed in
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".
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o Defining document: [this document] o Defining document: [this document]
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 3.3 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
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