SPF Authentication Failure Reporting using the Abuse Report Format
draft-ietf-marf-spf-reporting-08

MARF Working Group                                          S. Kitterman
Internet-Draft                                          Agari Data, Inc.
Updates: 4408 (if approved)                            February 28, 2012
Intended status: Standards Track
Expires: August 31, 2012

   SPF Authentication Failure Reporting using the Abuse Report Format
                    draft-ietf-marf-spf-reporting-08

Abstract

   This memo presents extensions to the Abuse Reporting Format (ARF),
   and Sender Policy Framework (SPF) specifications to allow for
   detailed reporting of message authentication failures in an on-demand
   fashion.

   This memo updates RFC4408 by providing an IANA registry for SPF
   modifiers.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on August 31, 2012.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   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.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Definitions  . . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  Keywords . . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.2.  Imported Definitions . . . . . . . . . . . . . . . . . . .  4
   3.  Optional Reporting Address for SPF . . . . . . . . . . . . . .  5
   4.  Requested Reports  . . . . . . . . . . . . . . . . . . . . . .  7
     4.1.  Requested Reports for SPF Failures . . . . . . . . . . . .  7
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  8
     5.1.  SPF Modifier Registration  . . . . . . . . . . . . . . . .  8
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
     6.1.  Inherited Considerations . . . . . . . . . . . . . . . . .  9
     6.2.  Additional forgery considertion  . . . . . . . . . . . . .  9
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     7.1.  Normative References . . . . . . . . . . . . . . . . . . . 10
     7.2.  Informative References . . . . . . . . . . . . . . . . . . 10
   Appendix A.  Acknowledgements  . . . . . . . . . . . . . . . . . . 11
   Appendix B.  Examples  . . . . . . . . . . . . . . . . . . . . . . 12
     B.1.  SPF DNS record for domain that sends no mail, but
           requests reports . . . . . . . . . . . . . . . . . . . . . 12
     B.2.  Minimal SPF DNS record change to add a reporting
           address  . . . . . . . . . . . . . . . . . . . . . . . . . 12
     B.3.  SPF DNS record with reporting address, report
           percentage, and requested report type  . . . . . . . . . . 12
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 13

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1.  Introduction

   [ARF] defines a message format for sending reports of abuse in the
   messaging infrastructure, with an eye toward automating both the
   generating and consumption of those reports.

   [SPF] is one mechanism for message sender authentication; it is
   "path-based" meaning it authenticates the route that a message took
   from origin to destination.  The output is a verified domain name
   that can then be subjected to some sort of evaluation process (e.g.,
   comparison to a known-good list, submission to a reputation service,
   etc.).

   This document extends [SPF] to add an optional reporting address and
   other parameters.  Extension of [ARF] to add features required for
   the reporting of these incidents is covered in
   [I-D.IETF-MARF-AUTHFAILURE-REPORT] and [I-D.IETF-MARF-AS].

   This document additionally creates a an IANA registry of [SPF] record
   modifiers to avoid modifier namespace collisions.

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2.  Definitions

2.1.  Keywords

   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.  Imported Definitions

   The ABNF token "qp-section" is defined in [MIME].

   "local-part" is defined in [MAIL].

   "addr-spec" is defined in [MAIL].

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3.  Optional Reporting Address for SPF

   There exist cases in which a domain name owner employing [SPF] for
   announcing sending practices may want to know when messages are
   received via unauthorized routing.  Currently there is no such method
   defined in conjunction with standardized approaches such as [ARF].
   Similar information can be gathered using a specially crafted [SPF]
   record and a special DNS server to track [SPF] record lookups.

   This document defines the following optional "modifier" (as defined
   in Section 4.6.1 of [SPF]) to SPF records, using the form defined in
   that specification:

   ra=  Reporting Address (plain-text; OPTIONAL; no default).  MUST be a
      local-part (see Section 3.4.1 of [MAIL]) specifying an e-mail
      address to which a report SHOULD be sent when mail claiming to be
      from this domain (see Section 2.4 of [SPF] for a description of
      how domains are identified for SPF checks) has failed the
      evaluation algorithm described in [SPF], in particular because a
      message arrived via an unauthorized route.  To generate a complete
      address to which the report is sent, the verifier simply appends
      to this value an "@" followed by the SPF domain per paragraph 4.1
      of [SPF]. ra= modifiers in a record that was reached by following
      an include: mechanism MUST be ignored.

      ABNF:

      spf-report-tag = %x72.61 "=" qp-section

   rp=  Requested Report Percentage (plain-text; OPTIONAL; default is
      "100").  The value is an integer from 0 to 100 inclusive that
      indicates what percentage of incidents of SPF failures, selected
      at random, are to cause reports to be generated.  The report
      generator SHOULD NOT issue reports for more than the requested
      percentage of incidents.  An exception to this might be some out-
      of-band arrangement between two parties to override it with some
      mutually agreed value.  Report generators MAY make use of the
      "Incidents:" field in [ARF] to indicate that there are more
      reportable incidents than there are reports.

      ABNF:

      spf-rp-tag = %x72.69 *WSP "=" *WSP 1*12DIGIT "/" 1*12DIGIT

   rr=  Requested Reports (plain-text; OPTIONAL; default is "all").  The
      value MUST be a colon-separated list of tokens representing those
      conditions under which a report is desired.  See Section 4.1 for a
      list of valid tags.

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      ABNF:

      spf-rr-type = ( "all" / "e" / "f" / "s" / "n" )

      spf-rr-tag = %x72.72 "=" spf-rr-type 0* ( ":" spf-rr-type )

   In the absence of an "ra=" tag in the SPF record, the "rp=" and "rr="
   tags MUST be ignored, and the report generator MUST NOT issue a
   report.

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4.  Requested Reports

   This memo also includes, as the "rr" tokens defined above, the means
   by which the sender can request reports for specific circumstances of
   interest.  Verifiers MUST NOT generate reports for incidents that do
   not match a requested report, and MUST ignore requests for reports
   not included in this list.

4.1.  Requested Reports for SPF Failures

   The following report requests are defined for SPF results:

   all  All reports are requested.

   e  Reports are requested for messages that produced an SPF result of
      "TempError" or "PermError".

   f  Reports are requested for messages that produced an SPF result of
      "Fail".

   s  Reports are requested for messages that produced an SPF result of
      "SoftFail".

   n  Reports are requested for messages that produced an SPF result of
      "Neutral" or "None".

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5.  IANA Considerations

   As required by [IANA-CONSIDERATIONS], this section contains registry
   information for the new [SPF] modifiers.

5.1.  SPF Modifier Registration

   IANA is requested to create the Sender Policy Framework Modifier
   Registry, to include a list of all registered SPF modifier names and
   their defining documents.

   New registrations or updates MUST be published in accordance with the
   "Specification Required" guidelines as described in
   [IANA-CONSIDERATIONS].  New registrations and updates MUST contain
   the following information:

   1.  Name of the modifier being registered or updated

   2.  The document in which the specification of the modifier is
       published

   3.  New or updated status, which MUST be one of:

       current:  The field is in current use

       deprecated:  The field is in current use but its use is
          discouraged

       historic:  The field is no longer in current use

   An update may make a notation on an existing registration indicating
   that a registered field is historic or deprecated if appropriate.

                 +------------+-----------------+---------+
                 | MODIFIER   | REFERENCE       | STATUS  |
                 +------------+-----------------+---------+
                 | exp        | RFC4408         | current |
                 | redirect   | RFC4408         | current |
                 | ra         | (this document) | current |
                 | rp         | (this document) | current |
                 | rr         | (this document) | current |
                 +------------+-----------------+---------+

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6.  Security Considerations

   Security issues with respect to these reports are similar to those
   found in [DSN].

6.1.  Inherited Considerations

   Implementors are advised to consider the Security Considerations
   sections of [SPF], [ARF], [I-D.IETF-MARF-AS], and
   [I-D.IETF-MARF-AUTHFAILURE-REPORT].

6.2.  Additional forgery considertion

   In addition to the advice in security considerations of
   [I-D.IETF-MARF-AS] the additional consderations apply to [SPF] auth
   failure reports.  If the MAIL FROM command is not the NULL return
   address, i.e., "MAIL FROM:<>", then the selected MAIL FROM address
   MUST pass [SPF] MAIL FROM checks on receipt.  The HELO/EHLO command
   SHOULD also be selected so that it will pass [SPF] HELO checks.

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7.  References

7.1.  Normative References

   [ARF]      Shafranovich, Y., Levine, J., and M. Kucherawy, "An
              Extensible Format for Email Feedback Reports", RFC 5965,
              August 2010.

   [I-D.IETF-MARF-AS]
              Falk, J. and M. Kucherawy, Ed., "Creation and Use of Email
              Feedback Reports: An Applicability Statement for the Abuse
              Reporting Format (ARF)", February 2012.

   [I-D.IETF-MARF-AUTHFAILURE-REPORT]
              Fontana, H., "Authentication Failure Reporting using the
              Abuse Report Format", January 2012.

   [IANA-CONSIDERATIONS]
              Alvestrand, H. and T. Narten, "Guidelines for Writing an
              IANA Considerations Section in RFCs", RFC 5226, May 2008.

   [KEYWORDS]
              Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", RFC 2119, March 1997.

   [MAIL]     Resnick, P., "Internet Message Format", RFC 5322,
              October 2008.

   [MIME]     Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part One: Format of Internet Message
              Bodies", RFC 2045, November 1996.

   [SPF]      Wong, M. and W. Schlitt, "Sender Policy Framework (SPF)
              for Authorizing Use of Domains in E-Mail, Version 1",
              RFC 4408, April 2006.

7.2.  Informative References

   [DSN]      Moore, K. and G. Vaudreuil, "An Extensible Message Format
              for Delivery Status Notifications", RFC 3464,
              January 2003.

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Appendix A.  Acknowledgements

   The author wishes to acknowledge the following for their review and
   constructive criticism of this proposal: Murray Kucherawy, Tim
   Draegen, Julian Mehnle, and John Levine.

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Appendix B.  Examples

B.1.  SPF DNS record for domain that sends no mail, but requests reports

   v=spf1 ra=postmaster -all

B.2.  Minimal SPF DNS record change to add a reporting address

   v=spf1 mx:example.org ra=postmaster -all

B.3.  SPF DNS record with reporting address, report percentage, and
      requested report type

   v=spf1 mx:example.org -all ra=postmaster rp=10 rr=e

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Author's Address

   Scott Kitterman
   Agari Data, Inc.
   3611 Scheel Dr
   Ellicott City, MD  21042
   US

   Phone: +1 301 325 5475
   Email: skitterman@agari.com

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