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Checking references for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: A later version (-26) exists of draft-ietf-httpbis-p1-messaging-23 -- Obsolete informational reference (is this intentional?): RFC 2616 (Obsoleted by RFC 7230, RFC 7231, RFC 7232, RFC 7233, RFC 7234, RFC 7235) Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 WEBSEC D. Ross 3 Internet-Draft Microsoft 4 Intended status: Informational T. Gondrom 5 Expires: January 30, 2014 Thames Stanley 6 July 29, 2013 8 HTTP Header Field X-Frame-Options 9 draft-ietf-websec-x-frame-options-07 11 Abstract 13 To improve the protection of web applications against Clickjacking, 14 this specification describes the X-Frame-Options HTTP response header 15 field that declares a policy communicated from the server to the 16 client browser on whether the browser may display the transmitted 17 content in frames that are part of other web pages. This 18 informational document serves to document the existing use and 19 specification of this X-Frame-Options HTTP response header field. 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at http://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on January 30, 2014. 38 Copyright Notice 40 Copyright (c) 2013 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (http://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 56 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 57 2. X-Frame-Options Header . . . . . . . . . . . . . . . . . . . 3 58 2.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 2.2. Augmented Backus-Naur Form (ABNF) . . . . . . . . . . . 4 60 2.2.1. Examples of X-Frame-Options . . . . . . . . . . . . . 5 61 2.3. Design Issues . . . . . . . . . . . . . . . . . . . . . . 5 62 2.3.1. Enable HTML content from other domains . . . . . . . 5 63 2.3.2. Browser Behaviour and Processing . . . . . . . . . . 6 64 2.3.2.1. Violation of X-Frame-Options . . . . . . . . . . 6 65 2.3.2.2. Variation in current browser behaviour . . . . . 6 66 2.3.2.3. Usage design pattern and example scenario for the 67 ALLOW-FROM parameter . . . . . . . . . . . . . . 7 68 3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 69 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 70 4.1. Registration Template . . . . . . . . . . . . . . . . . . 7 71 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 72 5.1. Privacy Considreations . . . . . . . . . . . . . . . . . 8 73 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 74 6.1. Normative References . . . . . . . . . . . . . . . . . . 8 75 6.2. Informative References . . . . . . . . . . . . . . . . . 9 76 Appendix A. Browsers that support X-Frame-Options . . . . . . . 10 77 Appendix B. Description of a Clickjacking attack . . . . . . . . 10 78 B.1. Shop . . . . . . . . . . . . . . . . . . . . . . . . . . 10 79 B.2. Online Shop Confirm Purchase Page . . . . . . . . . . . . 10 80 B.3. Flash Configuration . . . . . . . . . . . . . . . . . . . 11 81 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 83 1. Introduction 85 In 2009 and 2010 many browser vendors ([Microsoft-X-Frame-Options], 86 [CLICK-DEFENSE-BLOG], [Mozilla-X-Frame-Options]) introduced the use 87 of a non-standard HTTP [RFC2616] header field "X-Frame-Options" to 88 protect against Clickjacking [Clickjacking]. HTML-based web 89 applications can embed or "frame" other web pages. Clickjacking is a 90 type of attack that occurs when an attacker uses multiple transparent 91 or opaque layers in the user interface to trick a user into clicking 92 on a button or link on another page from server B when they were 93 intending to click on the same place of the overlaying page from 94 server A. Thus, the attacker is "hijacking" clicks meant for their 95 page A and routing them to another page B. The attacker is tricking 96 the user (who sees the overlaying user interface content from page A) 97 into clicking specific locations on the underlying page from server 98 B, triggering some actions on server B and potentially using an 99 existing session context in that step. This is an attack on both the 100 user and on server B. And server A may or may not be the attacker. 102 This specification provides informational documentation about the 103 current use and definition of the X-Frame-Options HTTP header field. 104 Given that the "X-" construction is deprecated [RFC6648], the X 105 -Frame-Options header field will in the future be replaced by the 106 Frame-Options directive in the Content Security Policy Version 1.1 107 [CSP-1-1]. 109 Existing anti-ClickJacking measures, e.g. Frame-breaking Javascript, 110 have weaknesses so that their protection can be circumvented as a 111 study [FRAME-BUSTING] demonstrated. 113 Short of configuring the browser to disable frames and script 114 entirely, which massively impairs browser utility, browser users are 115 vulnerable to this type of attack. 117 "X-Frame-Options" allows a secure web page from host B to declare 118 that its content (for example a button, links, text, etc.) must not 119 be displayed in a frame ( or