Multiple Vendor libwpd Multiple Buffer Overflow Vulnerabilities

iDefense Security Advisory 03.16.07
http://labs.idefense.com/intelligence/vulnerabilities/
Mar 16, 2007

I. BACKGROUND

libwpd is a C++ library used to decode and encode word perfect documents.
It is commonly used as a plug-in in word processing utilities such as Open
Office and Abiword. For more information please visit the following URL.

http://libwpd.sourceforge.net/

II. DESCRIPTION

Remote exploitation of multiple buffer overflow vulnerabilities in libwpd,
as included in various vendors' operating system distributions, could
allow an attacker to execute arbitrary code.

One problem specifically exists in the WP6GeneralTextPacket::_readContents
function. This function reads in a series of integer values and sums them.
This sum is then used to allocate a block of memory from the heap. The
function then copies data from the file into the buffer using each operand
from the addition as the number of bytes to copy. The summing operation
leads to an integer overflow, and the buffer can then be overflowed by the
copy operations.

Two additional problems exist in the WP3TablesGroup::_readContents() and
WP5DefinitionGroup_DefineTablesSubGroup::WP5DefinitionGroup_DefineTablesSubGroup()
functions. These functions read an integer value from an attacker supplied
file, and uses the value as a loop counter. In the loop a statically sized
buffer is filled with arbitrary data from the file. This leads to an
exploitable heap overflow.

III. ANALYSIS

Successful exploitation of these vulnerabilities requires an attacker to
persuade a user into opening a specially crafted Wordperfect (WPD)
document. If successful, the attacker could execute arbitrary code with
the permissions of the victim.

IV. DETECTION

iDefense has confirmed the existence of this vulnerability in libwpd
version 0.8.7. Previous versions may also be affected. This library is
used by applications such as Abiword, Kword, and Open Office.

V. WORKAROUND

iDefense is currently unaware of any workarounds for this issue.

VI. VENDOR RESPONSE

The libwpd maintainers have addressed these vulnerabilities with the
release of version 0.8.9.

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-0002 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

01/11/2007  Initial vendor notification
01/12/2007  Initial vendor response
03/16/2007  Coordinated public disclosure

IX. CREDIT

The first issue described was reported to iDefense by an anonymous
researcher.
Further analysis by Sean Larsson (iDefense Labs) lead to the discovery of
additional problems.

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X. LEGAL NOTICES

Copyright © 2007 iDefense, Inc.

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