Adobe Flash Player asfunction protocol may enable cross-site scripting

Overview

The Adobe Flash player asfunction protocol could allow an attacker to conduct cross-site scripting attacks on websites that host vulnerable Flash files.

Description

The Adobe Flash Player is a player for the Flash media format and enables frame-based animations and multimedia to be viewed within a web browser. ActionScript is a scripting language that is used to develop software and multimedia files that are processed by the Adobe Flash Player. The asfunction protocol enables HTTP hyperlinks in Flash files to launch a ActionScript functions.

Per Adobe Security Bulletin APSB07-20:
This update restricts the unsupported asfunction: protocol to address potential cross-site scripting issues with some SWF files. This issue is specific to Flash Player 8 and Flash Player 9 and does not affect Flash Player 7.

Note that vulnerable versions of the Flash Player may be distributed with various operating systems.

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Impact

A remote, unauthenticated attacker may be able to launch cross-site scripting attacks against sites that host vulnerable Flash files.

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Solution

Update Flash Player
Adobe has released an update to address this issue. Adobe Security Bulletin APSB07-20 contains more information about obtaining fixed software. Adobe Dreamweaver users may need to manually update their Flash player to obtain updates. See the Protocol Solutions Network Security Blog Adobe/Macromedia/Dreamweaver vulnerability posting for more information.

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Limit access to Flash files

Limiting access to untrusted Flash files can prevent cross-site scripting attacks that use Flash files. Disable ActiveX controls in the Internet Zone in Microsoft Internet Explorer. See Securing Your Web Browser for more information. Consider using the NoScript extension to whitelist web sites that can run Flash in Mozilla browsers such as Firefox. See the NoScript FAQ for more information.

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Vendor Information

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Updated: December 19, 2007

Status

Affected

Vendor Statement

We have not received a statement from the vendor.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

See <http://www.adobe.com/support/security/bulletins/apsb07-20.html&gt; for more details.

If you have feedback, comments, or additional information about this vulnerability, please send us [email](<mailto:[email protected]?Subject=VU%23758769 Feedback>).

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

• <http://www.adobe.com/support/security/bulletins/apsb07-20.html&gt;
• <http://www.adobe.com/support/flash/action_scripts/actionscript_dictionary/actionscript_dictionary073.html&gt;
• <http://www.adobe.com/products/flashplayer/&gt;
• <http://www.adobe.com/devnet/actionscript/&gt;
• <http://noscript.net/&gt;
• <http://noscript.net/features#contentblocking&gt;
• <http://www.adobe.com/licensing/developer/fileformat/faq/&gt;
• <http://www.us-cert.gov/reading_room/securing_browser/&gt;
• <http://www.protocolsolutions.co.uk/wordpress/?cat=4&gt;

Acknowledgements

Adobe credits Rich Cannings of the Google Security Team for reporting this issue.

This document was written by Ryan Giobbi.

Other Information

CVE IDs:	CVE-2007-6244
Severity Metric:	14.58 Date Public: