ScribeFire Firefox Extension - Privileged Code Injection

Type securityvulns
Reporter Securityvulns
Modified 2009-08-25T00:00:00


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ScribeFire Firefox Extension Code Injection Vulnerability Versions affected: < 3.4.2

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

The ScribeFire Firefox extension provides an interface for users to post to their blogs from any website. It allows users to drag images from a website into the editing pane, which publishes that image as part of their blog post. discovered that ScribeFire is vulnerable to multiple injection vulnerabilities which can be exploited through a malicious image. Cross-Site Scripting and HTML injection vulnerabilities were discovered within the DOM event handlers of <img> tags.

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

+------------+ |Exploitation| +------------+

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.

+--------+ |Solution| +--------+ follows responsible disclosure and promptly contacted the developer after discovering the issue. The developer was contacted on July 10, 2009, and a response was received on July 15. A fix was released on July 20, 2009.

The vendor supplied patch is available from Mozilla ( or from the developer’s personal website,

+------+ |Credit| +------+

Discovered and advised to the ScribeFire developer July 2009 by Nick Freeman of Contact: Nick Freeman \\AT\\ security-assess\m/ Personal Page:

For full details regarding this vulnerability (including a detailed proof of concept exploit) download the PDF from our website:

For more details regarding exploitation of Firefox extensions, refer to our DEFCON 17 presentation at is a New Zealand based world leader in web application testing, network security and penetration testing. services organisations across New Zealand, Australia, Asia Pacific, the United States and the United Kingdom.