Apple WebKit HTML Element Use After Free Vulnerability
17 Mar. 2010
Summary
Remote exploitation of a memory corruption vulnerability in WebKit, as included with multiple vendors' browsers, could allow an attacker to execute arbitrary code with the privileges of the current user.
Vulnerable Systems:
* Google Chrome 3.0.195.38 and prior.
* Safari 4.0.4 and prior.
* Apple WebKit
A full list of affected Apple products can be found in Security Advisory APPLE-SA-2010-03-11-1 Safari 4.0.5
Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the user viewing the Webpage. To exploit this vulnerability, a targeted user must load a malicious Webpage created by an attacker. An attacker typically accomplishes this via social engineering or injecting content into compromised, trusted sites. After the user visits the malicious Webpage, no further user interaction is needed.
Exploitation of this vulnerability is relatively simple if a heap spray technique is used to control large portions of heap memory. It is also trivial for an attacker to reallocate the chunk of freed memory and populate it with controlled values. This allows an attacker to control a C++ VTABLE, which leads to code execution. As such, this vulnerability is considered to be highly exploitable.
Patch Availability:
Apple Inc. has released a patch which addresses this issue. Information about downloadable vendor updates can be found by clicking on the URLs shown. http://www.apple.com/safari/download
Workaround:
The vulnerability is present in the JavaScript engine, so disabling JavaScript is an effective workaround. This can be performed via the command line with Google Chrome, and the Preferences menu in Safari.
