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Apple Safari RenderBox inlineBox Type Confusion Vulnerability

25.07.12

BACKGROUND

Safari is Apple's Web browser and is based on the open-source WebKit browser engine.

DESCRIPTION

Remote exploitation of a memory corruption vulnerability in Apple Inc.'s Safari browser could allow an attacker to execute arbitrary code with the privileges of the current user. The vulnerability occurs when Safari creates an element with the CSS run-in style. When this occurs, Safari creates a rendering object that is attached to the element. During further processing of the element, it is possible to make Safari treat the rendering object as a different type, which can lead to memory corruption and eventually code execution.

ANALYSIS

Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the user viewing the Web page. To exploit this vulnerability, a targeted user must load a malicious Web page 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 Web page, no further user interaction is needed.

DETECTION

iDefense has confirmed the existence of this vulnerability in Safari 5.0.5 on Windows XP. Previous versions and future versions may also be affected.

WORKAROUND

Disabling JavaScript is an effective workaround for this vulnerability. However, disabling scripting can severely impact the usability of the browser.

VENDOR RESPONSE

Apple Inc. has released an update which addresses this issue. For more information, consult their advisory at the following URL: http://lists.apple.com/archives/security-announce/2012/Jul/msg00000.html

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2012-3683 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org/), which standardizes names for security problems.

DISCLOSURE TIMELINE

06/01/2012 Initial Vendor Notification
06/02/2012 Initial Vendor Reply
07/25/2012 Coordinated Public Disclosure

CREDIT

This vulnerability was reported to iDefense by wushi of team509.

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LEGAL NOTICES

Copyright © 2012 Verisign, Inc.

Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDefense. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please e-mail customer service for permission.

Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.