Software Engineering Institute

Apple Safari fails to properly handle references to window objects. Safari can allow a window object to be deleted, while references to the object may still exist. If JavaScript code then attempts to use the deleted window object, this can result in the use of an invalid pointer. This pointer can be controlled by an attacker through the use of JavaScript.

Exploit code for this vulnerability is publicly available. We have confirmed Apple Safari 4.0.5 on the Windows platform to be vulnerable. Other versions may also be affected.

By convincing a victim to view an HTML document (webpage, HTML email, or email attachment) with Apple Safari, an attacker could run arbitrary code with the privileges of the user running the application.

Apply an update
This issue is addressed in Safari 5.0 and 4.1. Please see Apple document HT4196 for more details.

Disable JavaScript

This issue can be mitigated by disabling JavaScript in Apple Safari. Please see the Securing Your Web Browser document for more details.

Do not follow unsolicited links

In order to convince users to visit their sites, attackers often use URL encoding, IP address variations, long URLs, intentional misspellings, and other techniques to create misleading links. Do not click on unsolicited links received in email, instant messages, web forums, or internet relay chat (IRC) channels. Type URLs directly into the browser to avoid these misleading links. While these are generally good security practices, following these behaviors will not prevent exploitation of this vulnerability in all cases, particularly if a trusted site has been compromised or allows cross-site scripting.