Public Vulnerability Reports

Microsoft WordPad Word97 Converter Memory Corruption Vulnerability

09.14.10

BACKGROUND

WordPad is a word processing application included with Microsoft Windows. The Word97 converter is used to convert Word97 format documents into an RTF format used by WordPad. It is present in Windows 2000, Windows XP and Windows Server 2003 but not in Windows Vista, Windows Server 2008 and Windows 7.

DESCRIPTION

Remote exploitation of a memory corruption vulnerability in Microsoft Corp.'s WordPad could allow an attacker to execute arbitrary code with the privileges of the current user.

The vulnerability occurs when parsing the content inside of a Word97 format file. A byte value from the file is used as the count number of a memory write loop, but the code does not do any validation on this value. If a number bigger than the actual buffer length is supplied, it will corrupt memory and can lead to an exploitable condition.

ANALYSIS

Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the user opening the file. To exploit this vulnerability, an attacker needs to convince a user to open a malicious file. Usually, WordPad is associated with the .doc file extension when Office is not installed, but if Office is installed, it will take over the .doc extension; however, by renaming the .doc file to a .wri extension (associated with WordPad), it is possible to make WordPad open the file simply by double clicking it even when Office is installed.

DETECTION

iDefense has confirmed the existence of this vulnerability in WordPad version 5.1 for Windows XP SP3 and SP2. The following versions of Microsoft Windows are vulnerable:

 * Windows XP Service Pack 3 * Windows XP Professional x64 Edition Service Pack 2 * Windows Server 2003 Service Pack 2 * Windows Server 2003 x64 Edition Service Pack 2 * Windows Server 2003 with SP2 for Itanium-based systems 

WORKAROUND

Microsoft recommends disabling the WordPad Word 97 text converter by resricting access to the converter file.

VENDOR RESPONSE

Microsoft Corp. has released patches which address this issue. Information about downloadable vendor updates can be found by clicking on the URLs shown. http://www.microsoft.com/technet/security/bulletin/MS10-067.mspx

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2010-2563 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

04/28/2010 Initial Vendor Notification
04/28/2010 Initial Vendor Reply
09/14/2010 Coordinated Public Disclosure

CREDIT

This vulnerability was reported to iDefense by Hossein Lotfi (s0lute).

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LEGAL NOTICES

Copyright © 2010 Verisign, Inc.

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