Software Engineering Institute

XPCNativeWrapper

Per Mozilla, XPCNativeWrapper is a way to wrap up an object so that it is safe to access from privileged code. It is used to allow chrome code to access DOM objects.

The Problem

An attacker can use the XPCNativeWrapper function to inject script into a browser window that may be in a different domain. This violates the Netscape same-origin policy.

By convincing a victim to view an HTML document (web page), an attacker could evaluate script in a different security domain than the one containing the attacker's document. The attacker could read or modify data in other web sites (read cookies/content, modify/create content, etc.). If the script is evaluated with chrome privileges, an attacker could execute arbitrary commands on the user's system.

Upgrade
This issue is addressed in the 1.5.0.5 updates to Mozilla Firefox and Thunderbird, and the 1.0.3 version of Seamonkey. Refer to Mozilla Foundation Security Advisory 2006-54 for more details.

Disable JavaScript

For instructions on how to disable JavaScript in Firefox, please refer to the Firefox section of the Securing Your Web Browser document. JavaScript is not enabled by default in Mozilla Thunderbird.