[Full-disclosure] iDefense Security Advisory 06.10.08: Multiple Vendor FreeType2 PFB Memory Corruption Vulnerability



iDefense Security Advisory 06.10.08
http://labs.idefense.com/intelligence/vulnerabilities/
Jun 10, 2008

I. BACKGROUND

FreeType2 is an open source library for parsing fonts that is used by
many applications. This includes projects such as X.Org, Second Life,
and the Sun Java JRE. For more information, please see the vendor's
website at the following URL.

http://freetype.sourceforge.net/freetype2/

II. DESCRIPTION

Remote exploitation of a memory corruption vulnerability in the
FreeType2 library, as included in various vendors' operating systems,
could allow an attacker to execute arbitrary code with the privileges
of the affected application.

The vulnerability exists within the code responsible for parsing Printer
Font Binary (PFB) format font files. By providing an invalid 'number of
axes' in the file, it is possible to cause the code to call the free()
function on areas of memory that were not dynamically allocated. This
can lead to memory corruption, which can allow for the execution of
arbitrary code.

III. ANALYSIS

Exploitation of this vulnerability results in the execution of arbitrary
code with the privileges of the application using the library. Since
FreeType2 is a library and not a standalone application, the
exploitation vector will vary. iDefense Labs verified that local
privilege escalation was possible via the X.Org Xserver.

IV. DETECTION

iDefense has confirmed the existence of this vulnerability in FreeType2
version 2.3.5. Previous versions may also be affected.

V. WORKAROUND

iDefense is currently unaware of any workarounds for this issue.
Changing the permissions on the freetype.so library may not always be
effective since applications that run with root privileges are not
restricted by file permissions.

VI. VENDOR RESPONSE

The FreeType maintainers addressed this vulnerability with the release
of version 2.3.6. For more information, refer to the release notes at
the following URL.

http://sourceforge.net/project/shownotes.php?group_id=3157&release_id=605780

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2008-1807 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org/), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

06/03/2008 Initial vendor notification
06/04/2008 Initial vendor response
06/10/2008 Coordinated public disclosure

IX. CREDIT

This vulnerability was reported to iDefense by regenrecht.

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X. LEGAL NOTICES

Copyright © 2008 iDefense, 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 customerservice@xxxxxxxxxxxx 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.

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