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Multiple Vendor libgsf Heap Overflow Vulnerability

BACKGROUND

The GNOME Structured File Library is a utility library for reading and writing structured file formats. This library replaces libole2 and is used in projects such as gnumeric, mrproject, abiword, libwv2 and koffice. It is generally used to access MS OLE2 streams. For more information, see:

http://freshmeat.net/projects/libgsf/

DESCRIPTION

Remote exploitation of a heap overflow vulnerability in libgsf, as included in various vendors' operating system distributions, could allow an attacker to execute arbitrary code.

The problem specifically exists in the 'ole_init_info' function; the function only obtains enough for the number specified in 'num_bat' when allocating memory. Later, when reading the file contents, the number specified in 'num_metabat' is used as the bounds for a loop. Due to insufficient validation of the aforementioned variables, an attacker could cause a heap overflow.

ANALYSIS

Successful exploitation of this vulnerability requires an attacker to persuade a user into opening a specially crafted OLE document. If successful, the attacker could execute arbitrary code with the permissions of the victim.

Inside of the 'ole_info_read_metabat' function, values read from the file are validated to be within a range which depends on the size of the file. Successful exploitation may be somewhat mitigated by this validation. However, as file size increases, the number of allowed values increases.

DETECTION

iDefense has confirmed the existence of this vulnerability in version 1.14.0 of the Gnome Structured File library. Any applications or libraries that utilize this library for OLE should be considered vulnerable.

WORKAROUND

iDefense is unaware of any effective workarounds at this time.

VENDOR RESPONSE

The libgsf maintainers have addressed this problem with version 1.14.2.

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2006-4514 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

08/17/2006 Initial vendor notification
08/17/2006 Initial vendor response
11/30/2006 Coordinated public disclosure

CREDIT

This vulnerability was reported to iDefense by infamous41md.

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LEGAL NOTICES

Copyright © 2006 Verisign, Inc.

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