REPUTE Working Group N. Borenstein Internet-Draft Mimecast Intended status: Standards Track M. Kucherawy Expires: May 23, 2013 November 19, 2012 A Reputation Response Set for Email Identifiers draft-ietf-repute-email-identifiers-06 Abstract This document defines a response set for describing assertions a reputation service provider can make about email identifers, for use in generating reputons. 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 http://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 May 23, 2013. Copyright Notice Copyright (c) 2012 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 (http://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. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Borenstein & Kucherawy Expires May 23, 2013 [Page 1] Internet-Draft Email Identifiers Reputation Response Set November 2012 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology and Definitions . . . . . . . . . . . . . . . . . . 3 2.1. Key Words . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2. Email Definitions . . . . . . . . . . . . . . . . . . . . . 3 2.3. Other Definitions . . . . . . . . . . . . . . . . . . . . . 3 3. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Assertions . . . . . . . . . . . . . . . . . . . . . . . . 3 3.2. Response Set Extensions . . . . . . . . . . . . . . . . . . 4 3.3. Query Extensions . . . . . . . . . . . . . . . . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 4.1. Registration of 'email-id' Reputation Application . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6.1. Normative References . . . . . . . . . . . . . . . . . . . 6 6.2. Informative References . . . . . . . . . . . . . . . . . . 7 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 7 Appendix B. Public Discussion . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Borenstein & Kucherawy Expires May 23, 2013 [Page 2] Internet-Draft Email Identifiers Reputation Response Set November 2012 1. Introduction This document specifies a response set for describing reputation of an email identifier. A "response set" in this context is defined in [I-D.REPUTE-MODEL] and is used to describe assertions a reputation service provider can make about email identifiers as well as meta- data that can be included in such a reply beyond the base set specified there. An atomic reputation response is called a "reputon", also defined in that document. 2. Terminology and Definitions This section defines terms used in the rest of the document. 2.1. Key Words The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [KEYWORDS]. 2.2. Email Definitions Commonly used definitions describing entities in the email architecture are defined and discussed in [EMAIL-ARCH]. 2.3. Other Definitions Other terms of importance in this document are defined in [I-D.REPUTE-MODEL], the base document for the reputation services work. 3. Discussion The expression of reputation about an email identifier requires extensions of the base set defined in [I-D.REPUTE-MODEL]. This document defines and registers some common assertions about an entity found in a piece of [MAIL]. 3.1. Assertions The "email-id" reputation application recognizes the following assertions: Borenstein & Kucherawy Expires May 23, 2013 [Page 3] Internet-Draft Email Identifiers Reputation Response Set November 2012 abusive: The subject identifier is associated with sending or handling > email of a personally abusive, threatening, or otherwise harassing nature. fraud: The subject identifier is associated with sending or handling of fraudulent email, such as "phishing" (some good discussion on this topic can be found in [IODEF-PHISHING]) invalid-recipients: The subject identifier is associated with delivery attempts to nonexistent recipients malware: The subject identifier is associated with the sending or handling of malware via email spam: The subject identifier is associated with sending or handling of unwanted bulk email 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 all accumulated data support the assertion, and the intervening values have a linear relationship (i.e., a score of "x" is twice as strong of an assertion as a value of "x/2"). 3.2. Response Set Extensions The "email-id" reputation application recognizes the following OPTIONAL extensions to the basic response set defined in [I-D.REPUTE-MEDIA-TYPE]: identity: A token indicating the source of the identifier; that is, where the subject identifier was found in the message. This MUST be one of: dkim: The signing domain, i.e. the value of the "d=" tag, found on a valid [DKIM] signature in the message ipv4: The IPv4 address of the client ipv6: The IPv6 address of the client rfc5321.helo: The RFC5321.Helo value used by the (see [SMTP]) client rfc5321.mailfrom: The RFC5321.MailFrom value of the envelope of the message (see [SMTP]) Borenstein & Kucherawy Expires May 23, 2013 [Page 4] Internet-Draft Email Identifiers Reputation Response Set November 2012 rfc5322.from: The RFC5322.From field of the message (see [MAIL]) spf: The domain name portion of the identifier (RFC5321.MailFrom or RFC5321.Helo) verified by [SPF]) sources: A token relating a count of the number of sources of data that contributed to the reported reputation. This is in contrast to the "sample-size" parameter, which indicates the total number of reports across all reporting sources. A reply that does not contain the "identity" or "sources" extensions is making a non-specific statement about how the reputation returned was developed. A client can use or ignore such a reply at its discretion. 3.3. Query Extensions A query within this application can include the OPTIONAL query parameter "identity" to indicate which specific identity is of interest to the query. Legal values are the same as those listed in Section 3.2. 4. IANA Considerations This memo presents one action for IANA, namely the registration of the reputation application "email-id". 4.1. Registration of 'email-id' Reputation Application This section registers the "email-id" reputation application, as per the IANA Considerations section of [I-D.REPUTE-MODEL]. The registration parameters are as folows: o Application name: email-id o Short description: Evaluates DNS domain names or IP addresses found in email identifiers o Defining document: [this document] o Status: current o Subject: A string appropriate to the identifier of interest (see Section 3.2 of this document) o Application-specific query parameters: Borenstein & Kucherawy Expires May 23, 2013 [Page 5] Internet-Draft Email Identifiers Reputation Response Set November 2012 identity: (current) as defined in Section 3.3 of this document o Application-specific assertions: abusive: (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 document malware: (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: identity: (current) as defined in Section 3.2 of this document 5. Security Considerations This document is primarily an IANA action and doesn't describe any protocols or protocol elements that might introduce new security concerns. Security considerations relevant to email and email authentication can be found in most of the documents listed in the References sections below. Information specific to use of reputation services can be found in [I-D.REPUTE-CONSIDERATIONS]. 6. References 6.1. Normative References [DKIM] Crocker, D., Ed., Hansen, T., Ed., and M. Kucherawy, Ed., "DomainKeys Identified Mail (DKIM) Signatures", RFC 6376, September 2011. [EMAIL-ARCH] Crocker, D., "Internet Mail Architecture", RFC 5598, July 2009. [I-D.REPUTE-MEDIA-TYPE] Borenstein, N. and M. Kucherawy, "A Media Type for Reputation Interchange", draft-ietf-repute-media-type (work in progress), November 2012. Borenstein & Kucherawy Expires May 23, 2013 [Page 6] Internet-Draft Email Identifiers Reputation Response Set November 2012 [I-D.REPUTE-MODEL] Borenstein, N. and M. Kucherawy, "A Model for Reputation Reporting", draft-ietf-repute-model (work in progress), November 2012. [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [SPF] Wong, M. and W. Schlitt, "Sender Policy Framework (SPF) for Authorizing Use of Domains in E-Mail, Version 1", RFC 4408, April 2006. 6.2. Informative References [I-D.REPUTE-CONSIDERATIONS] Kucherawy, M., "Operational Considerations Regarding Reputation Services", draft-ietf-repute-considerations (work in progress), November 2012. [IODEF-PHISHING] Cain, P. and D. Jevans, "Extensions to the IODEF-Document Class for Reporting Phishing", RFC 5901, July 2010. [MAIL] Resnick, P., Ed., "Internet Message Format", RFC 5322, October 2008. [SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, October 2008. Appendix A. Acknowledgments The authors wish to acknowledge the contributions of the following to this specification: Scott Hollenbeck, Scott Kitterman, Peter Koch, John Levine, Danny McPherson, S. Moonesamy, Doug Otis, and David F. Skoll. Appendix B. 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. Borenstein & Kucherawy Expires May 23, 2013 [Page 7] Internet-Draft Email Identifiers Reputation Response Set November 2012 Authors' Addresses Nathaniel Borenstein Mimecast 203 Crescent St., Suite 303 Waltham, MA 02453 USA Phone: +1 781 996 5340 Email: nsb@guppylake.com Murray S. Kucherawy 2063 42nd Avenue San Francisco, CA 94116 USA Email: superuser@gmail.com Borenstein & Kucherawy Expires May 23, 2013 [Page 8]