WEBSEC D. Ross
Internet-Draft Microsoft
Intended status: Standards Track T. Gondrom
Expires: September 8, 2011 March 7, 2011
HTTP Header Frame Options
draft-gondrom-frame-options-00
Abstract
To improve the protection of web applications against Cross Site
Request Forgery (CSRF) and Clickjacking this standards defines a http
response header that declares a policy communicated from a host to
the client browser whether the transmitted content MUST NOT be
displayed in frames of other pages from different origins or a list
of trusted origins which are allowed to frame the content.
Status of this Memo
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This Internet-Draft will expire on September 8, 2011.
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Ross & Gondrom Expires September 8, 2011 [Page 1]
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3
2. Frame-Options Header . . . . . . . . . . . . . . . . . . . . . 3
2.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Backus-Naur Form (BNF) . . . . . . . . . . . . . . . . . . 4
2.3. Examples of Frame-Options Headers . . . . . . . . . . . . . 4
3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Registration Template . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . . 5
Appendix A. Description of a Clickjacking attack . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6
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1. Introduction
In 2009 and 2010 many browser vendors introduced the use of a non-
standard http header RFC 2616 [RFC2616] "X-Frame-Options" to protect
against Clickjacking [Clickjacking] and Cross Site Request Forgery
(CSRF) [CSRF]. This standard is to replace the non-standard header.
With Clickjacking and CSRF an attacker tricks a user into clicking on
a button or link to another page and by thus executing an unintended
command in the context of a different web application. For example
with Clickjacking the attacker might use transparent or opaque layers
to integrate and obscure a button to another page so that the user
may click on it in the expectation of a different action. So, in
this way the attacker is "hijacking" the "Click" on a button meant by
the user to be sent to host A, while clicking the button in effect
sends a message to host B. If the user does for example also have an
open session with host B this can lead to a CSRF attack and executing
a command in the session context of the user (using the user's
authentication and authorization) on host B without his intention or
knowledge.
The by "Frame-Options" provided defense mechanism against
Clickjacking is to allow a secure web page from host B to declare
that its content (for example a button, links, text, etc.) must not
be displayed in a frame of another page (e.g. from host A). In
principle this is done by a policy declared in the HTTP header and
obeyed by conform browser implementations.
1.1. Requirements Language
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 RFC 2119 [RFC2119].
2. Frame-Options Header
The Frame-Options HTTP response header indicates a policy whether a
browser MUST NOT allow to render a page in a or