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UNIRAS Brief - 792/06 - iDefense Security Advisory 11.30.06 - Multiple Vendor libgsf Heap Overflow Vulnerability



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       UNIRAS (UK Government CERT) Briefing - 792/06 Dated 01.12.06 Time 13:55  

UNIRAS is part of NISCC (the UK National Infrastructure Security  Co-ordination Centre)
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 	UNIRAS material is available from the NISCC website at www.niscc.gov.uk
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Title
=====

iDefense Security Advisory 11.30.06 - Multiple Vendor libgsf Heap Overflow Vulnerability

Detail
======

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.


Multiple Vendor libgsf Heap Overflow Vulnerability

iDefense Security Advisory 11.30.06
http://labs.idefense.com/intelligence/vulnerabilities/
Nov 30, 2006

I. 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/

II. 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.

III. 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.

IV. 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.

V. WORKAROUND

iDefense is unaware of any effective workarounds at this time.

VI. VENDOR RESPONSE

The libgsf maintainers have addressed this problem with version 1.14.2.

VII. 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.

VIII. DISCLOSURE TIMELINE

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

IX. CREDIT

This vulnerability was reported to iDefense by infamous41md.

Get paid for vulnerability research
http://labs.idefense.com/methodology/vulnerability/vcp.php

Free tools, research and upcoming events http://labs.idefense.com/

X. LEGAL NOTICES

Copyright C 2006 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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UNIRAS wishes to acknowledge the contributions of iDefense for the information contained 

in this briefing.
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This notice contains information released by the original author. Some of the information may have changed since it was released. If
the vulnerability affects you, it may be prudent to retrieve the advisory from the site of the original source to ensure that you
receive the most current information concerning that problem.

Reference to any specific commercial product, process, or service by trade name, trademark manufacturer, or otherwise, does not
constitute or imply its endorsement, recommendation, or favouring by UNIRAS or NISCC. The views and opinions of authors expressed
within this notice shall not be used for advertising or product endorsement purposes.

Neither UNIRAS or NISCC shall also accept responsibility for any errors or omissions contained within this briefing notice. In
particular, they shall not be liable for any loss or damage whatsoever, arising from or in connection with the usage of information
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UNIRAS is a member of the Forum of Incident Response and Security Teams (FIRST) and has contacts with other international Incident
Response Teams (IRTs) in order to foster cooperation and coordination in incident prevention, to prompt rapid reaction to incidents,
and to promote information sharing amongst its members and the community at large.
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<End of UNIRAS Briefing>



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