Microsoft Excel Macro Security Features Can Be Bypassed by Malformed Excel Documents
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SecurityTracker Alert ID: 1002486 |
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SecurityTracker URL: http://securitytracker.com/id/1002486
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CVE Reference:
CAN-2001-0718
(Links to External Site)
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Date: Oct 5 2001
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Impact:
Execution of arbitrary code via network
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Fix Available: Yes Vendor Confirmed: Yes
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Version(s): Microsoft Excel 2000 for Windows, Excel 2002 for Windows, Excel 98 for Macintosh, Excel 2001 for Macintosh
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Description:
Microsoft reported that a malformed Excel document can bypass the Excel macro security features. A remote user could supply a malformed Excel spreadsheet that would cause arbitrary code to be execute on the target user's host when the file is opened.
It is reported that there is a flaw in the way that Excel attempts to detect macros. A remote user could create a specially formated Excel document that contains malicious macro code that would run automatically when the target user opened the file.
A similar vulnerability exists in Microsoft PowerPoint. See a separate Alert for information on the PowerPoint vulnerability.
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Impact:
A remote user could create an Excel document that contains malicious macro code that would bypass the Excel macro security features and be executed when the recipient of the file opens the file.
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Solution:
Microsoft has issued patches, which are available at the following locations:
Download locations for this patch
Microsoft Excel 2000 for Windows:
http://download.microsoft.com/download/excel2000/e2kmac/1/w98nt42kme/en-us/e2kmac.exe
Microsoft Excel 2002 for Windows:
http://download.microsoft.com/download/excel2002/exc1001/1/w98nt42kme/en-us/exc1001.exe
Microsoft Excel 98 for Macintosh:
http://www.microsoft.com/mac/download/office98/pptxlmacro.asp
Microsoft Excel 2001 for Macintosh:
http://www.microsoft.com/mac/download/office2001/pptxlmacro.asp
The vendor reports that the above listed patches can be installed on systems running Excel SR-1 or SP2 for Windows and systems running Excel for Macintosh. For information on applying and verifying patches, see the Vendor URL.
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Vendor URL: www.microsoft.com/technet/security/bulletin/MS01-050.asp (Links to External Site)
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Cause:
Exception handling error
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Underlying OS:
MacOS, Windows (Me), Windows (NT), Windows (95), Windows (98), Windows (2000)
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Message History:
None.
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Source Message Contents
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Date: Thu, 4 Oct 2001 14:56:03 -0700
Subject: Microsoft Security Bulletin MS01-050
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The following is a Security Bulletin from the Microsoft Product Security
Notification Service.
Please do not reply to this message, as it was sent from an unattended
mailbox.
********************************
-----BEGIN PGP SIGNED MESSAGE-----
- ----------------------------------------------------------------------
Title: Malformed Excel or PowerPoint Document Can Bypass Macro
Security
Date: 04 October 2001
Software: Microsoft Excel or PowerPoint for Windows or Macintosh
Impact: Run Code Of Attacker's Choice
Bulletin: MS01-050
Microsoft encourages customers to review the Security Bulletin at:
http://www.microsoft.com/technet/security/bulletin/MS01-050.asp.
- ----------------------------------------------------------------------
Issue:
======
Excel and PowerPoint have a macro security framework that controls
the execution of macros and prevents macros from running
automatically. Under this framework, any time a user opens a
document the document is scanned for the presence of macros.
If a document contains macros, the user is notified and asked
if he wants to run the macros or the macros are disabled entirely,
depending on the security setting. A flaw exists in the way macros
are detected that can allow a malicious user to bypass macro
checking.
A malicious attacker could attempt to exploit this vulnerability
by crafting a specially formed Excel or PowerPoint document with
macro code that would run automatically when the user opened it.
The attacker could carry out this attack by hosting the malicious
file on a web site, a file share, or by sending it through email.
Mitigating Factors:
====================
- The macro code could not execute without the user's
first opening the document.
Patch Availability:
===================
- A patch is available to fix this vulnerability. Please read the
Security Bulletin at
http://www.microsoft.com/technet/security/bulletin/ms01-050.asp
for information on obtaining this patch.
Acknowledgment:
===============
- Peter Ferrie, Symantec Security Response
(http://securityresponse.symantec.com)
- ---------------------------------------------------------------------
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