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[Full-disclosure] Yoono Firefox Extension - Privileged Code Injection

From: Nick Freeman <nick.freeman_at_nospam>
Date: Wed Jan 13 2010 - 10:05:04 GMT
To: full-disclosure@lists.grok.org.uk

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Yoono Firefox Extension Code Injection Vulnerability Versions affected: < 6.1.1

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|Description|
+-----------+

The Yoono Firefox extension provides an interface for users to share objects with their friends on social networks from any website. It allows users to select images from a website to be shared, which publishes that image to their friends.

Security-Assessment.com discovered that Yoono's share function is vulnerable to DOM event handler injection. The vulnerability affects the DOM event handlers of <img> tags which can be shared via Yoono.

Yoono's share function directly evaluates remotely supplied content, within the privileged chrome context. This can allow a malicious image on a website to exploit users who share it, and may lead to the complete compromise of the host.     

+------------+
|Exploitation|
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This vulnerability can be exploited in several ways. As the injection point is in the chrome privileged browser zone, it is possible to bypass Same Origin Policy (SOP) protections, and also access Mozilla built-in XPCOM components. XPCOM components can be used to read and write from the file system, as well as execute arbitrary commands, steal stored passwords,  or modify other Firefox extensions.

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|Solution|
+--------+

Security-Assessment.com follows responsible disclosure and promptly contacted the developer after discovering the issue. The developer was contacted on June 30, 2009, and a response was received on the same day. A fix was released on July 6, 2009.

The vendor supplied patch is available
from Mozilla (https://addons.mozilla.org/en-US/firefox/addon/1833) or from the developer’s website, http://www.yoono.com.

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|Credit|
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Discovered and advised to the Yoono developers June 2009 by Nick Freeman of Security-Assessment.com. Contact: Nick Freeman \\AT\\ security-assess\m/ent.com Personal Page: http://atta.cked.me

For full details regarding this vulnerability (including a detailed proof of concept exploit) download the PDF from our website:
http://security-assessment.com/files/advisories/Yoono_Firefox_Extension_Privileged_Code_Injection.pdf

For more details regarding exploitation of Firefox extensions, refer to our DEFCON 17 presentation at http://security-assessment.com/files/presentations/liverani_freeman_abusing_firefox_extensions_defcon17.pdf.

Security-Assessment.com is a New Zealand based world leader in web application testing, network security and penetration testing. Security-Assessment.com services organisations across New Zealand, Australia, Asia Pacific, the United States and the United Kingdom.



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