First-Party-Only Cookies
draft-west-first-party-cookies-03

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Last updated 2015-05-13
Replaced by draft-ietf-httpbis-cookie-same-site
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HTTPbis                                                          M. West
Internet-Draft                                               Google, Inc
Updates: 6265 (if approved)                                 May 13, 2015
Intended status: Standards Track
Expires: November 14, 2015

                        First-Party-Only Cookies
                   draft-west-first-party-cookies-03

Abstract

   This document updates RFC6265 by defining a "First-Party-Only"
   attribute which allows servers to assert that a cookie ought to be
   sent only in a "first-party" context.  This assertion allows user
   agents to mitigate the risk of cross-origin information leakage, and
   provides some minimal protection against cross-site request forgery
   attacks.

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
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   This Internet-Draft will expire on November 14, 2015.

Copyright Notice

   Copyright (c) 2015 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

West                    Expires November 14, 2015               [Page 1]
Internet-Draft             first-party-cookies                  May 2015

   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Goals . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Limitations . . . . . . . . . . . . . . . . . . . . . . .   3
     1.3.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Terminology and notation  . . . . . . . . . . . . . . . . . .   4
     2.1.  First-party and Third-party Requests  . . . . . . . . . .   5
       2.1.1.  Document-based requests . . . . . . . . . . . . . . .   5
       2.1.2.  Worker-based requests . . . . . . . . . . . . . . . .   7
   3.  Server Requirements . . . . . . . . . . . . . . . . . . . . .   8
     3.1.  Grammar . . . . . . . . . . . . . . . . . . . . . . . . .   8
     3.2.  Semantics of the "First-Party-Only" Attribute (Non-
           Normative)  . . . . . . . . . . . . . . . . . . . . . . .   9
   4.  User Agent Requirements . . . . . . . . . . . . . . . . . . .   9
     4.1.  The "First-Party-Only" attribute  . . . . . . . . . . . .   9
     4.2.  Monkey-patching the Storage Model . . . . . . . . . . . .   9
     4.3.  Monkey-patching the "Cookie" header . . . . . . . . . . .  10
   5.  Authoring Considerations  . . . . . . . . . . . . . . . . . .  10
     5.1.  Mashups and Widgets . . . . . . . . . . . . . . . . . . .  10
   6.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  10
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  12
   Appendix A.  Acknowledgements . . . . . . . . . . . . . . . . . .  12
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   Section 8.2 of [RFC6265] eloquently notes that cookies are a form of
   ambient authority, attached by default to requests the user agent
   sends on a user's behalf.  Even when an attacker doesn't know the
   contents of a user's cookies, she can still execute commands on the
   user's behalf (and with the user's authority) by asking the user
   agent to send HTTP requests to unwary servers.

   Here, we update [RFC6265] with a simple mitigation strategy that
   allows servers to declare certain cookies as "First-party-only",
   meaning they should be attached to requests if and only if those
   requests occur in a first-party context (as defined in section 2.1).

   Note that the mechanism outlined here is backwards compatible with
   the existing cookie syntax.  Servers may serve first-party cookies to
   all user agents; those that do not support the "First-Party-Only"

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