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iDefense Security Advisory 06.10.08: Multiple Vendor FreeType2 PFB Integer Overflow Vulnerability
iDefense Security Advisory 06.10.08
Jun 10, 2008
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.
Remote exploitation of an integer overflow 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. PFB files contain a section known
as the "Private" dictionary table which is used to describe how
characters are constructed. When parsing this data structure, a series
of 16-bit length values are read in from the file. These values are
added together and used to allocate a dynamic buffer. The addition can
result in an integer overflow, which subsequently leads to a heap
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.
iDefense has confirmed the existence of this vulnerability in FreeType2
version 2.3.5. Previous versions may also be affected.
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.
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2008-1806 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org/), which standardizes names for
VIII. DISCLOSURE TIMELINE
06/03/2008 Initial vendor notification
06/04/2008 Initial vendor response
06/10/2008 Coordinated public disclosure
This vulnerability was reported to iDefense by regenrecht.
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Copyright © 2008 iDefense, 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,
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