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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.
II. DESCRIPTION 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 overflow.
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.
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 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.
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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.