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Sun Java JRE TrueType Font Parsing Heap Overflow Vulnerability

12.04.08

BACKGROUND

The Sun Java JRE is Sun's implementation of the Java runtime. For more information, see the vendor's site found at the following link.

http://www.java.com

DESCRIPTION

Remote exploitation of a heap overflow vulnerability in Sun Microsystems Inc.'s Java JRE could allow an attacker to execute arbitrary code with the privileges of the current user.

The vulnerability exists within the font parsing code in the JRE. Various types of fonts are supported, one of which is the TrueType format font. The vulnerability occurs when processing TrueType font files. During parsing, improper bounds checking is performed, which can lead to a heap based buffer overflow.

ANALYSIS

Exploitation allows attackers to execute arbitrary code in the context of the currently logged-on user. 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.

The content of the overflow buffer undergoes a series of transformations during the font decoding process. The data is not entirely controlled by the attacker, but there is likely enough control to allow for the overwriting of critical data structures in a manner that makes exploitation possible.

DETECTION

iDefense has confirmed the existence of this vulnerability in Sun Microsystem Inc.'s Java JRE version 1.6.0_07 for Windows. Previous versions and versions for other platforms may also be affected.

WORKAROUND

iDefense is currently unaware of any workarounds for this vulnerability.

VENDOR RESPONSE

Sun Microsystem Inc. has released a patch which addresses this issue. For more information, consult their advisories at the following URL.

http://onesearch.sun.com/onesearch/index.jsp?qt=Bug%206751322&charset=UTF-8

CVE INFORMATION

A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not been assigned yet.

DISCLOSURE TIMELINE

09/10/2008 Initial Vendor Notification
10/28/2008 Initial Vendor Reply
11/25/2008 Additional Vendor Feedback
12/02/2008 Coordinated Public Disclosure

CREDIT

This vulnerability was discovered by Sean Larsson, iDefense Labs.

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LEGAL NOTICES

Copyright © 2008 Verisign, Inc.

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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.