Monday, May 09, 2005

BROWSER SECURITY ALERT: Mozilla Firefox Code Execution Vulnerabilities Found

An advisory has been issued at concerning two vulnerabilities within Firefox. I just thought it important to let all my readers know. Here are the details:

Two vulnerabilities have been discovered in Firefox, which can be exploited by malicious people to conduct cross-site scripting attacks and compromise a user's system.

1) The problem is that "IFRAME" JavaScript URLs are not properly protected from being executed in context of another URL in the history list. This can be exploited to execute arbitrary HTML and script code in a user's browser session in context of an arbitrary site.

2) Input passed to the "IconURL" parameter in "InstallTrigger.install()" is not properly verified before being used. This can be exploited to execute arbitrary JavaScript code with escalated privileges via a specially crafted JavaScript URL.

Successful exploitation requires that the site is allowed to install software (default sites are "" and "").

A combination of vulnerability 1 and 2 can be exploited to execute arbitrary code.

NOTE: Exploit code is publicly available.

The vulnerabilities have been confirmed in version 1.0.3. Other versions may also be affected.

1) Disable JavaScript.

2) Disable software installation: Options --> Web Features --> "Allow web sites to install software"

NOTE: A temporary solution has been added to the sites "" and "" where requests are redirected to "". This will stop the publicly available exploit code using a combination of vulnerability 1 and 2 to execute arbitrary code in the default settings of Firefox.

Sources: | Mozilla Security Advisories
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