HTTP Header Field X-Frame-Options
RFC 7034
Internet Engineering Task Force (IETF) D. Ross
Request for Comments: 7034 Microsoft
Category: Informational T. Gondrom
ISSN: 2070-1721 Thames Stanley
October 2013
HTTP Header Field X-Frame-Options
Abstract
To improve the protection of web applications against clickjacking,
this document describes the X-Frame-Options HTTP header field, which
declares a policy, communicated from the server to the client
browser, regarding whether the browser may display the transmitted
content in frames that are part of other web pages.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7034.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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described in the Simplified BSD License.
Ross & Gondrom Informational [Page 1]
RFC 7034 X-Frame-Options October 2013
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. X-Frame-Options Header . . . . . . . . . . . . . . . . . . . . 4
2.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Augmented Backus-Naur Form (ABNF) . . . . . . . . . . . . 5
2.2.1. Examples of X-Frame-Options . . . . . . . . . . . . . 6
2.3. Design Issues . . . . . . . . . . . . . . . . . . . . . . 6
2.3.1. Enable HTML Content from Other Domains . . . . . . . . 6
2.3.2. Browser Behavior and Processing . . . . . . . . . . . 6
2.3.2.1. Violation of X-Frame-Options . . . . . . . . . . . 6
2.3.2.2. Variation in Current Browser Behavior . . . . . . 7
2.3.2.3. Usage Design Pattern and Example Scenario for
the ALLOW-FROM Parameter . . . . . . . . . . . . . 8
2.3.2.4. No Caching of the X-Frame-Options Header . . . . . 8
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
3.1. Registration Template . . . . . . . . . . . . . . . . . . 9
4. Security Considerations . . . . . . . . . . . . . . . . . . . 9
4.1. Privacy Considerations . . . . . . . . . . . . . . . . . . 10
5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. Normative References . . . . . . . . . . . . . . . . . . . 10
5.2. Informative References . . . . . . . . . . . . . . . . . . 11
Appendix A. Browsers That Support X-Frame-Options . . . . . . . . 13
Appendix B. Description of a Clickjacking Attack . . . . . . . . 13
B.1. Shop . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
B.2. Online Shop Confirm Purchase Page . . . . . . . . . . . . 13
B.3. Flash Configuration . . . . . . . . . . . . . . . . . . . 13
Appendix C. Acknowledgements . . . . . . . . . . . . . . . . . . 13
Ross & Gondrom Informational [Page 2]
RFC 7034 X-Frame-Options October 2013
1. Introduction
In 2009 and 2010, many browser vendors ([Microsoft-X-Frame-Options],
[CLICK-DEFENSE-BLOG], and [Mozilla-X-Frame-Options]) introduced the
use of a non-standard HTTP [RFC2616] header field "X-Frame-Options"
to protect against clickjacking [Clickjacking]. HTML-based web
applications can embed or "frame" other web pages. Clickjacking is a
type of attack that occurs when an attacker uses multiple transparent
or opaque layers in the user interface to trick a user into clicking
on a button or link on another page from server B when they were
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