Forwarded from: "Marc Maiffret" <marcat_private> Microsoft WordPerfect Document Converter Buffer Overflow Release Date: September 3, 2003 Reported Date: May 6, 2003 Severity: Medium (Code Execution with User Interaction) Systems Affected: Microsoft Office 97, 2000, XP Microsoft Word 98 (J) Microsoft FrontPage 2000, 2002 Microsoft Publisher 2000, 2002 Microsoft Works Suite 2001, 2002, 2003 Description: The Microsoft Word "WordPerfect" document converter included in Microsoft Word has a buffer overflow bug. If the WordPerfect document converter is installed (by default it is in Office 2000) and a malicious .doc file is opened, there exists the ability for an attacker to execute arbitrary code. This buffer overflow bug can also happen within Internet Explorer, because Microsoft Word is executed automatically as a helper-application when a .doc file is received. This buffer overflow overwrites the return address in the stack area. We confirmed that arbitrary code can be executed by using this buffer overflow bug. Technical Description: While parsing a WordPerfect file, the WordPerfect converter copies data stored in the .doc file to a local buffer. If we modify some bytes of the .doc file, we can specify the data offset and data size. The WordPerfect converter doesn't properly check the size of the data contained in the .doc file, and tries to copy all of the data from the file to the local buffer allocated in the stack area. This results in a typical buffer overflow vulnerability in which we can set any value for EIP. The process for making the .doc file to confirm this buffer overflow is as follows: [Technical data may wrap in eMail, please visit our website.] 1. Open Word and save an empty document as wordPerfect 5.0 file. 2. Open the .doc file in a binary editor. You'll be able to confirm the following dump image: ADDRESS 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 0123456789ABCDEF ---------------------------------------------------------------------------- -- 00000000 FF 57 50 43 6D 02 00 00 01 0A 00 00 00 00 00 00 .WPCm........... ... 00000130 00 00 00 00 CD 01 00 00 08 00 02 00 00 00 CD 01 ................ ... 000001C0 61 75 74 68 6F 72 00 65 45 79 65 00 00 00 00 FB author.eEye..... 000001D0 FF 05 00 32 00 00 00 00 00 01 01 6C 00 00 00 01 ...2.......l.... 000001E0 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000001F0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 3. Modify 0x00 to 0x01 in offset 0x00000139. 4. Modify 0x00 to the value more than 0x80 in offset 0x000001D8. 5. Modify 0x00 to the value more than 0x01 in offset 0x000001E1 to 0x000001FF. 6. Append garbage data (e.g., a long string of A's) onto the end of this file. Protection: Retina Network Security Scanner has been updated to identify this vulnerability. Vendor Status: Microsoft was notified on May 6, 2003, and has released a patch for this vulnerability. The patch is available at: http://www.microsoft.com/technet/security/bulletin/MS03-036.asp Credit: Yuji "The Ninja" Ukai, eEye Digital Security Related Links: Retina Network Security Scanner - Free 15 Day Trial http://www.eeye.com/html/Products/Retina/index.html Greetings: Shanti, Yukkie, TEX, Sakuranamiki people, AD200X people Copyright (c) 1998-2003 eEye Digital Security Permission is hereby granted for the redistribution of this alert electronically. It is not to be edited in any way without express consent of eEye. If you wish to reprint the whole or any part of this alert in any other medium excluding electronic medium, please e-mail alertat_private for permission. Disclaimer The information within this paper may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties with regard to this information. In no event shall the author be liable for any damages whatsoever arising out of or in connection with the use or spread of this information. Any use of this information is at the user's own risk. Feedback Please send suggestions, updates, and comments to: eEye Digital Security http://www.eEye.com infoat_private - ISN is currently hosted by Attrition.org To unsubscribe email majordomoat_private with 'unsubscribe isn' in the BODY of the mail.
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