draft-ietf-websec-x-frame-options-01.txt   draft-ietf-websec-x-frame-options-02.txt 
WEBSEC D. Ross WEBSEC D. Ross
Internet-Draft Microsoft Internet-Draft Microsoft
Intended status: Informational T. Gondrom Intended status: Informational T. Gondrom
Expires: April 26, 2013 October 23, 2012 Expires: August 29, 2013 Thames Stanley
February 25, 2013
HTTP Header X-Frame-Options HTTP Header Field X-Frame-Options
draft-ietf-websec-x-frame-options-01 draft-ietf-websec-x-frame-options-02
Abstract Abstract
To improve the protection of web applications against Clickjacking To improve the protection of web applications against Clickjacking,
this standard defines an http response header that declares a policy this specification describes the X-Frame-Options HTTP response header
communicated from a host to the client browser on whether the browser field that declares a policy communicated from the server to the
must not display the transmitted content in frames of other web client browser on whether the browser may display the transmitted
pages. This drafts serves to document the existing use and content in frames that are part of other web pages. This
specification of X-Frame-Options. informational document serves to document the existing use and
specification of this X-Frame-Options HTTP response header field.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 26, 2013. This Internet-Draft will expire on August 29, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. X-Frame-Options Header . . . . . . . . . . . . . . . . . . . . 3 2. X-Frame-Options Header . . . . . . . . . . . . . . . . . . . . 3
2.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Backus-Naur Form (BNF) . . . . . . . . . . . . . . . . . . 4 2.2. Augmented Backus-Naur Form (ABNF) . . . . . . . . . . . . 5
2.3. Design Issues . . . . . . . . . . . . . . . . . . . . . . . 5 2.2.1. Examples of X-Frame-Options . . . . . . . . . . . . . 5
2.3.1. Enable HTML content from other domains . . . . . . . . 5 2.2.2. Variations of the ALLOW-FROM field . . . . . . . . . . 5
2.3.2. Browser Behaviour and Processing . . . . . . . . . . . 5 2.3. Design Issues . . . . . . . . . . . . . . . . . . . . . . 5
2.4. Examples of X-Frame-Options Headers . . . . . . . . . . . . 6 2.3.1. Enable HTML content from other domains . . . . . . . . 5
2.4.1. Example scenario for the ALLOW-FROM parameter . . . . . 6 2.3.2. Browser Behaviour and Processing . . . . . . . . . . . 6
3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 2.3.2.1. Violation of X-Frame-Options . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 2.3.2.2. Variation in current browser behaviour . . . . . . 6
4.1. Registration Template . . . . . . . . . . . . . . . . . . . 7 2.3.2.3. Usage design pattern and example scenario for
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 the ALLOW-FROM parameter . . . . . . . . . . . . . 7
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
6.1. Normative References . . . . . . . . . . . . . . . . . . . 7 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6.2. Informative References . . . . . . . . . . . . . . . . . . 7 4.1. Registration Template . . . . . . . . . . . . . . . . . . 8
Appendix A. Description of a Clickjacking attack . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
A.1. Shop . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 5.1. Privacy Considreations . . . . . . . . . . . . . . . . . . 9
A.2. Confirm Purchase Page . . . . . . . . . . . . . . . . . . . 9 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
A.3. Flash Configuration . . . . . . . . . . . . . . . . . . . . 9 6.1. Normative References . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 6.2. Informative References . . . . . . . . . . . . . . . . . . 9
Appendix A. Browsers that support X-Frame-Options . . . . . . . . 10
Appendix B. Description of a Clickjacking attack . . . . . . . . 10
B.1. Shop . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
B.2. Online Shop Confirm Purchase Page . . . . . . . . . . . . 11
B.3. Flash Configuration . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction 1. Introduction
In 2009 and 2010 many browser vendors ([Microsoft-X-Frame-Options], In 2009 and 2010 many browser vendors ([Microsoft-X-Frame-Options],
[CLICK-DEFENSE-BLOG], [Mozilla-X-Frame-Options]) introduced the use [CLICK-DEFENSE-BLOG], [Mozilla-X-Frame-Options]) introduced the use
of a non-standard http header RFC 2616 [RFC2616] "X-Frame-Options" to of a non-standard HTTP [RFC2616] header field "X-Frame-Options" to
protect against Clickjacking [Clickjacking]. This draft is to protect against Clickjacking Clickjacking [Clickjacking]. HTML-based
document the current use of X-Frame-Options header and shall in the web applications can embed or "frame" other web pages. Clickjacking
future be replaced by the Frame-Options [FRAME-OPTIONS] standard. 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 intending to click on the same place of the overlaying page
from server A. Thus, the attacker is "hijacking" clicks meant for
their page A and routing them to another page B, possibly belonging
to another domain and thereby triggering actions on the second server
B without the knowledge nor intention of the user and potentially
using an existing session context and login in that step.
This specification provides informational documentation about the
current use and definition of the X-Frame-Options HTTP header field.
Given that the "X-" construction is deprecated [RFC6648], the
X-Frame-Options header field will in the future be replaced by the
Frame-Options directive in the Content Security Policy Version 1.1
[CSP-1-1].
Existing anti-ClickJacking measures, e.g. Frame-breaking Javascript, Existing anti-ClickJacking measures, e.g. Frame-breaking Javascript,
have weaknesses so that their protection can be circumvented as a have weaknesses so that their protection can be circumvented as a
study [FRAME-BUSTING] demonstrated. study [FRAME-BUSTING] demonstrated.
Short of configuring the browser to disable frames and script Short of configuring the browser to disable frames and script
entirely, which massively impairs browser utility, browser users are entirely, which massively impairs browser utility, browser users are
vulnerable to this type of attack. vulnerable to this type of attack.
The "X-Frame-Options" allows a secure web page from host B to declare "X-Frame-Options" allows a secure web page from host B to declare
that its content (for example a button, links, text, etc.) must not that its content (for example a button, links, text, etc.) must not
be displayed in a frame (<frame> or <iframe>) of another page (e.g. be displayed in a frame (<frame> or <iframe>) of another page (e.g.
from host A). In principle this is done by a policy declared in the from host A). In principle this is done by a policy declared in the
HTTP header and obeyed by conform browser implementations. HTTP header and enforced by conforming browser implementations.
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
2. X-Frame-Options Header 2. X-Frame-Options Header
The X-Frame-Options HTTP response header indicates a policy whether a The X-Frame-Options HTTP response header field indicates a policy on
browser MUST NOT allow to render a page in a <frame> or <iframe> . whether the browser should render the transmitted resource within a
Hosts can declare this policy in the header of their HTTP responses <frame> or <iframe>. Servers can declare this policy in the header
to prevent clickjacking attacks, by ensuring that their content is of their HTTP responses to prevent clickjacking attacks, and by this
not embedded into other pages or frames. ensuring that their content is not embedded into other pages or
frames.
2.1. Syntax 2.1. Syntax
The header field name is: The header field name is:
X-Frame-Options X-Frame-Options
There are three different values for the header field. These values There are three different values for the header field. These values
are exclusive, that is NOT more than one of the three values MUST be are mutually exclusive, that is exactly one of the three values MUST
set. be set.
DENY DENY
A browser receiving content with this header MUST NOT display A browser receiving content with this header MUST NOT display
this content in any frame. this content in any frame.
SAMEORIGIN SAMEORIGIN
A browser receiving content with this header MUST NOT display A browser receiving content with this header field MUST NOT
this content in any frame from a page of different origin than display this content in any frame from a page of different
the content itself. origin than the content itself.
If a browser or plugin can not reliably determine whether the If a browser or plugin can not reliably determine whether the
origin of the content and the frame have the same origin, this origin of the content and the frame have the same origin, this
MUST be treated as "DENY". MUST be treated as "DENY".
(Please note that current implementations may vary on the Please note that current implementations vary on the
interpretation of this criteria: In some it only allows to be interpretation of this criteria: In some it only allows to be
framed if the origin of the top-level browsing-context is framed if the origin of the top-level browsing-context is
identical, in other it compares with to the origin of the identical to the origin of the content using the X-FRAME-
framing page.) OPTIONS directive, in others it may compare to the origin of
the framing page.
ALLOW-FROM (followed by a URI [RFC3986] of a trusted origin) ALLOW-FROM (followed by a URI [RFC3986] of a trusted origin)
A browser receiving content with this header MUST NOT display A browser receiving content with this header MUST NOT display
this content in a frame from any page with a top-level browsing this content in a frame from any page with a top-level browsing
contex of different origin than the specified origin. While context of different origin than the specified origin. While
this can expose the page to risks by the trusted origin, in this can expose the page to risks by the trusted origin, in
some cases it may be necessary to allow the framing by content some cases it may be necessary to allow the framing by content
from other domains. from other domains.
For example: X-FRAME-OPTIONS: ALLOW-FROM:
https://www.domain.com/
The ALLOW-FROM URI MUST be valid. If the ALLOW-FROM value is used, it MUST be followed by a valid URI.
Any data beyond the domain address (i.e. any data after the "/" Any data beyond the domain address (i.e. any data after the "/"
separator) is to be ignored. And the algorithm to compare origins separator) is to be ignored. And the algorithm to compare origins
from [RFC6454] SHOULD be used to verify a referring page is of the from [RFC6454] SHOULD be used to verify that a referring page is of
same origin as the content or that the referring page's origin is the same origin as the content or that the referring page's origin is
identical with the ALLOW-FROM URI. identical with the ALLOW-FROM URI. Though in conflict with
[RFC6454], current implementations do not consider the port as a
defining component of the origin.
Wildcards or lists to declare multiple domains in one ALLOW-FROM Wildcards or lists to declare multiple domains in one ALLOW-FROM
statement are not permitted. statement are not permitted.
Please note that in conflict with [RFC6454], current implementations 2.2. Augmented Backus-Naur Form (ABNF)
do not consider the port as a defining component of the origin.
2.2. Backus-Naur Form (BNF) The RFC 2234 [RFC2234] ABNF of the X-Frame-Options header is:
The RFC 822 [RFC0822] EBNF of the X-Frame-Options header is: X-Frame-Options = "DENY"
/ "SAMEORIGIN"
/ ( "ALLOW-FROM" RWS URI )
X-Frame-Options = "Frame-Options" ":" "DENY"/ "SAMEORIGIN" / With URI as defined in [RFC3986] and RWS and OWS as defined in
("ALLOW-FROM" ":" URI) [HTTPbis-P1]. The values are specified as ABNF strings, and
therefore are case-insensitive.
With URI as defined in [RFC3986] 2.2.1. Examples of X-Frame-Options
[TBD] Or should we use the ABNF (RFC 2234) alternatively to EBNF or
in addition? X-FRAME-OPTIONS: DENY
X-FRAME-OPTIONS: SAMEORIGIN
X-FRAME-OPTIONS: ALLOW-FROM https://example.com/
2.2.2. Variations of the ALLOW-FROM field
Regarding the syntax, it should be noted that existing
implementations have variations in whether a colon (":") should be
between "ALLOW-FROM" and the URI. E.g. in IE8+ the colon ":" is not
needed, while Firefox and Chrome implementations at the time of
writing of this document support both forms.
Alternative ABNF of the X-Frame-Options header:
X-Frame-Options = "DENY"
/ "SAMEORIGIN"
/ ( "ALLOW-FROM" OWS ":" OWS URI )
2.3. Design Issues 2.3. Design Issues
2.3.1. Enable HTML content from other domains 2.3.1. Enable HTML content from other domains
There are three main direct vectors that enable HTML content from There are a number of main direct vectors that enable HTML content
other domains: from other domains:
o IFRAME Tag
o IFRAME tag
o Frame tag o Frame tag
o The Object tag (requires a redirect) o The Object tag (requires a redirect)
o Applet tag
o Embed tag
Besides these, other ways to host HTML content can be possible. For Besides these, other ways to host HTML content can be possible. For
example some plugins may host HTML views directly. If these plugins example some plugins may host HTML views directly. If these plugins
appear essentially as frames (as opposed to top-level windows), the appear essentially as frames (as opposed to top-level windows), the
plugins MUST conform to the X-FRAME-OPTIONS directive as specified in plugins MUST conform to the X-FRAME-OPTIONS policy as specified in
this draft as well. this document as well.
2.3.2. Browser Behaviour and Processing 2.3.2. Browser Behaviour and Processing
To allow secure implementations, browsers MUST behave in a consistent To allow secure implementations, browsers must behave in a consistent
and reliable way. and reliable way.
If an HTTP Header prohibits framing, the user-agent of the browser If an X-Frame-Options HTTP header field prohibits framing, the user-
MAY immediately abort downloading or parsing of the document. agent of the browser MAY immediately abort downloading or parsing of
the document.
When a browser discovers loaded content with the X-FRAME-OPTIONS 2.3.2.1. Violation of X-Frame-Options
header would be displayed in a frame against the specified origin
When a browser discovers that loaded content with the X-FRAME-OPTIONS
header field would be displayed in a frame against the specified
orders of the header, the browser SHOULD redirect as soon as possible orders of the header, the browser SHOULD redirect as soon as possible
to a "No-Frame" page. to a "No-Frame" page.
"No-Frame" Page "No-Frame" Page
If the display of content is denied by the X-FRAME-OPTIONS header an If the display of content is denied by the X-FRAME-OPTIONS header an
error page SHOULD be displayed. For example this can be a error page SHOULD be displayed. For example this can be a
noframe.html page also stating the full URL of the protected page and noframe.html page also stating the full URL of the protected page and
the hostname of the protected page. the hostname of the protected page.
The NoFrame page MAY provide the user with an option to open the The NoFrame page MAY provide the user with an option to open the
target URL in a new window. target URL in a new window.
Variation in current browser behaviour Implementations of this vary, some browsers will show a message that
allows the user to safely open the target page in a new window.
Other implementations will simply render an empty frame.
2.3.2.2. Variation in current browser behaviour
There are currently variations in the implementation of the X-FRAME- There are currently variations in the implementation of the X-FRAME-
OPTIONS header. For example not all browsers may support the "ALLOW- OPTIONS header. For example not all browsers support the "ALLOW-
FROM" option. FROM" option. "ALLOW-FROM" was initially an IE (Internet Explorer)
And the criteria for SAMEORIGIN option is not evaluated unanimously: extension and at the time of writing has not been uniformly
one implementation may evaluate the SAMEORIGIN option based on the implemented by other user agents.
origin of the framed page and the framing page, while another may
evaluate based on the framed page and the top-level browsing-context And the criteria for the SAMEORIGIN option is not evaluated
unanimously either: one implementation may evaluate the SAMEORIGIN
option based on the origin of the framed page and the framing page,
while another may evaluate based on the framed page and the top-level
browsing-context.
These variations in the evaluation of the header by different These variations in the evaluation of the header by different
implementations impair the useage and reliability of this http implementations impair the useage and reliability of this http
header. A revised version of frame-options [FRAME-OPTIONS] shall header. A revised version of x-frame-options in the form of a frame-
unify the behaviour and replace this document in the future. options directive in the CSP 1.1[CSP-1-1] shall unify the behaviour
and replace this document in the future.
2.4. Examples of X-Frame-Options Headers 2.3.2.3. Usage design pattern and example scenario for the ALLOW-FROM
parameter
2.4.1. Example scenario for the ALLOW-FROM parameter As the "ALLOW-FROM" field does support only one URI, in cases when
the server wishes to allow more than one resource to frame its
content, the following design pattern is recommended:
1. Inner IFRAME suggests via a querystring parameter what site it 1. A page that wants to render the requested content in a frame
wants to be hosted by. This can obviously be specified by an supplies its own origin information to the server providing the
attacker, but that's OK. to-be-framed content via a querystring parameter.
2. Server verifies the hostname meets whatever criteria. For 2. The Server verifies the hostname meets its criteria so that the
example, for a Facebook "Like" button, the server can check to page can be allowed to be framed by the target resource. This
see that the supplied hostname matches the hostname expected for may for example happen via a look-up of a white-list of trusted
that Like button. domain names that are allowed to frame the page. For example,
for a Facebook "Like" button, the server can check to see that
the supplied hostname matches the hostname(s) expected for that
"Like" button.
3. Server serves up the hostname in X-FRAME-OPTIONS: ALLOW-FROM if 3. The server return the hostname in X-FRAME-OPTIONS: ALLOW-FROM if
the proper criteria was met in step #2. the proper criteria was met in step #2.
4. Browser enforces the X-FRAME-OPTIONS: ALLOW-FROM domain.com 4. The browser enforces the X-FRAME-OPTIONS: ALLOW-FROM header.
header.
3. Acknowledgements 3. Acknowledgements
This document was derived from input from specifications published by This document was derived from input from specifications published by
various browser vendors like Microsoft (Eric Lawrence, David Ross), various browser vendors like Microsoft (Eric Lawrence, David Ross),
Mozilla, Google, Opera and Apple. Mozilla, Google, Opera and Apple.
4. IANA Considerations 4. IANA Considerations
This memo a request to IANA to include the specified HTTP header in This memo is a request to IANA to include the specified HTTP header
registry as outlined in Registration Procedures for Message Header in the registry as outlined in Registration Procedures for Message
Fields [RFC3864] Header Fields [RFC3864]
4.1. Registration Template 4.1. Registration Template
PERMANENT MESSAGE HEADER FIELD REGISTRATION TEMPLATE: PERMANENT MESSAGE HEADER FIELD REGISTRATION TEMPLATE:
Header field name: X-Frame-Option Header field name: X-Frame-Option
Applicable protocol: http [RFC2616] Applicable protocol: http [RFC2616]
Status: Standard Status: Standard
skipping to change at page 7, line 25 skipping to change at page 8, line 31
Author/Change controller: IETF Author/Change controller: IETF
Specification document(s): draft-ietf-websec-x-frame-options Specification document(s): draft-ietf-websec-x-frame-options
Related information: Related information:
Figure 1 Figure 1
5. Security Considerations 5. Security Considerations
The introduction of the http header X-FRAME-OPTIONS does improve the The introduction of the X-FRAME-OPTIONS http header field does
protection against Clickjacking, however it is not self-sufficient on improve the protection against Clickjacking. However, it is not
its own but MUST be used in conjunction with other security measures self-sufficient on its own, but must be used in conjunction with
like secure coding and Content Security Policy (CSP) other security measures like secure coding and the Content Security
Policy [CSP].
It is important to note that current implementations do not check the
origins of the entire ancestor tree of frames of the framing
resources, and this may expose the resource to attack in multiply-
nested scenarios. For example, if a resource on origin A embeds
untrusted content from origin B, that untrusted content can embed
another resource from origin A with an X-Frame-Options: SAMEORIGIN
policy and that check would pass if the user agent only verifies the
top-level browsing context.
Furthermore, X-Frame-Options must be sent as an HTTP header field and
is explicitly ignored by user agents when declared with a meta http-
equiv tag.
5.1. Privacy Considreations
The parameter ALLOW-FROM allows a page to guess who is framing it. The parameter ALLOW-FROM allows a page to guess who is framing it.
This is by design, but may lead to data leakage or data protection This is inherent by design, but may lead to data leakage or data
concerns. protection concerns.
6. References 6. References
6.1. Normative References 6.1. Normative References
[HTTPbis-P1]
IETF, "Hypertext Transfer Protocol (HTTP/1.1): Message
Syntax and Routing", 2013, <http://tools.ietf.org/html/
draft-ietf-httpbis-p1-messaging-22>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005.
[RFC6454] Barth, A., "The Web Origin Concept", RFC 6454,
December 2011.
6.2. Informative References 6.2. Informative References
[CLICK-DEFENSE-BLOG] [CLICK-DEFENSE-BLOG]
Microsoft, "Clickjacking Defense", 2009, <http:// Microsoft, "Clickjacking Defense", 2009, <http://
blogs.msdn.com/b/ie/archive/2009/01/27/ blogs.msdn.com/b/ie/archive/2009/01/27/
ie8-security-part-vii-clickjacking-defenses.aspx>. ie8-security-part-vii-clickjacking-defenses.aspx>.
[CSP] W3C, "Content Security Policy 1.0", November 2012,
<http://www.w3.org/TR/CSP/>.
[CSP-1-1] W3C, "Content Security Policy 1.1", December 2012,
<http://www.w3.org/TR/CSP11/>.
[Clickjacking] [Clickjacking]
OWASP (Open Web Application Security Project), OWASP (Open Web Application Security Project),
"Clickjacking", 2010, "Clickjacking", 2010,
<http://www.owasp.org/index.php/Clickjacking>. <http://www.owasp.org/index.php/Clickjacking>.
[FRAME-BUSTING] [FRAME-BUSTING]
Stanford Web Security Research, "Busting frame busting: a Stanford Web Security Research, "Busting frame busting: a
study of clickjacking vulnerabilities at popular sites", study of clickjacking vulnerabilities at popular sites",
2010, <http://seclab.stanford.edu/websec/framebusting/>. 2010, <http://seclab.stanford.edu/websec/framebusting/>.
[FRAME-OPTIONS]
IETF, "The Web Origin Concept", July 2012, <http://
tools.ietf.org/id/draft-ietf-websec-frame-options-00.txt>.
[Microsoft-X-Frame-Options] [Microsoft-X-Frame-Options]
Microsoft, "Combating ClickJacking With X-Frame-Options", Microsoft, "Combating ClickJacking With X-Frame-Options",
2010, <http://blogs.msdn.com/b/ieinternals/archive/2010/ 2010, <http://blogs.msdn.com/b/ieinternals/archive/2010/
03/30/combating-clickjacking-with-x-frame-options.aspx>. 03/30/combating-clickjacking-with-x-frame-options.aspx>.
[Mozilla-X-Frame-Options] [Mozilla-X-Frame-Options]
Mozilla, "The X-Frame-Options response header", 2010, <htt Mozilla, "The X-Frame-Options response header", 2010, <htt
ps://developer.mozilla.org/en-US/docs/ ps://developer.mozilla.org/en-US/docs/
The_X-FRAME-OPTIONS_response_header>. The_X-FRAME-OPTIONS_response_header>.
[RFC0822] Crocker, D., "Standard for the format of ARPA Internet
text messages", STD 11, RFC 822, August 1982.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration
Procedures for Message Header Fields", BCP 90, RFC 3864, Procedures for Message Header Fields", BCP 90, RFC 3864,
September 2004. September 2004.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC6648] Saint-Andre, P., Crocker, D., and M. Nottingham,
Resource Identifier (URI): Generic Syntax", STD 66, "Deprecating the "X-" Prefix and Similar Constructs in
RFC 3986, January 2005. Application Protocols", BCP 178, RFC 6648, June 2012.
[RFC6454] Barth, A., "The Web Origin Concept", RFC 6454, Appendix A. Browsers that support X-Frame-Options
December 2011.
Appendix A. Description of a Clickjacking attack o Internet Explorer 8+
o Firefox 3.6.9+
o Opera 10.5+
o Safari 4+
o Chrome 4.1+
Appendix B. Description of a Clickjacking attack
More detailed explanation of Clickjacking scenarios More detailed explanation of Clickjacking scenarios
A.1. Shop B.1. Shop
An Internet Marketplace/Shop offering a feature with a link/button to An Internet Marketplace/Shop offering a feature with a link/button to
"Buy this" Gadget "Buy this" Gadget
The marketplace wants their affiliates (who could be bad guys) to be The marketplace wants their affiliates (who could be malicious
able to stick the "Buy such-and-such from XYZ" IFRAMES into their attackers) to be able to stick the "Buy such-and-such from XYZ"
pages. There is a ClickJack possibility here, which is why the IFRAMES into their pages. There is a possible Clickjacking threat
marketplace/onlineshop needs to then immediately navigate the main here, which is why the marketplace/onlineshop needs to then
browsing context (or a new window) to a confirmation page which is immediately navigate the main browsing context (or a new window) to a
protected by anti-CJ protections. confirmation page which is protected by anti-Clickjacking
protections.
A.2. Confirm Purchase Page B.2. Online Shop Confirm Purchase Page
Onlineshop "Confirm purchase" anti-CSRF page The "Confirm Purchase"" page of an online shop must be shown to the
The Confirm Purchase page must be shown to the end user without end user without the risk of an overlay or misuse by an attacker.
possibility of overlay or misuse by an attacker. For that reason, For that reason, the confirmation page uses a combination of anti-
the confirmation page uses anti-CSRF tokens and contains the X-FRAME- CSRF tokens and the X-FRAME-OPTIONS HTTP header field, mitigating
OPTIONS directive, mitigating ClickJack attacks. ClickJacking attacks.
A.3. Flash Configuration B.3. Flash Configuration
Macromedia Flash configuration page
Macromedia Flash configuration settings are set by a Flash object Macromedia Flash configuration settings are set by a Flash object
which can run only from a specific configuration page on Macromedia's which can run only from a specific configuration page on Macromedia's
site. The object runs inside the page and thus can be subject to a site. The object runs inside the page and thus can be subject to a
ClickJacking attack. In order to prevent ClickJacking attacks ClickJacking attack. In order to prevent ClickJacking attacks
against the security settings, the configuration page uses the against the security settings, the configuration page uses the
X-FRAME-OPTIONS directive. X-FRAME-OPTIONS directive.
Authors' Addresses Authors' Addresses
David Ross David Ross
Microsoft Microsoft
U.S. U.S.
Phone: Phone:
Email: Email:
Tobias Gondrom Tobias Gondrom
Thames Stanley
Kruegerstr. 5A Kruegerstr. 5A
Unterschleissheim, Unterschleissheim,
Germany Germany
Phone: +44 7521003005 Phone: +44 7521003005
Email: tobias.gondrom@gondrom.org Email: tobias.gondrom@gondrom.org
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