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Credit:
The information has been provided by Microsoft Security.
The original article can be found at: http://www.microsoft.com/technet/security/Bulletin/MS06-027.mspx
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Vulnerable Systems:
* Microsoft Office 2000 Service Pack 3
* Microsoft Word 2000 Download the update (KB917345)
* Microsoft Office XP Service Pack 3
* Microsoft Word 2002 Download the update (KB917335)
* Microsoft Office 2003 Service Pack 1 or Service Pack 2
* Microsoft Word 2003 Download the update (KB917334)
* Microsoft Word Viewer 2003 - Download the update (KB917346)
* Microsoft Works Suites:
* Microsoft Works Suite 2000 - Download the update (KB917345) (same as Microsoft Word 2000 update)
* Microsoft Works Suite 2001 - Download the update (KB917345) (same as Microsoft Word 2000 update)
* Microsoft Works Suite 2002 - Download the update (KB917335) (same as the Microsoft Word 2002 update)
* Microsoft Works Suite 2003 - Download the update (KB917335) (same as the Microsoft Word 2002 update)
* Microsoft Works Suite 2004 - Download the update (KB917335) (same as the Microsoft Word 2002 update)
* Microsoft Works Suite 2005 - Download the update (KB917335) (same as the Microsoft Word 2002 update)
* Microsoft Works Suite 2006 - Download the update (KB917335) (same as the Microsoft Word 2002 update)
Immune Systems:
* Microsoft Word v. X for Mac
* Microsoft Word 2004 for Mac
Microsoft Word Malformed Object Pointer Vulnerability - CVE-2006-2492
A remote code execution vulnerability exists in Word using a malformed object pointer. An attacker could exploit the vulnerability by constructing a specially crafted Word file that could allow remote code execution.
If a user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less affected than users who operate with administrative user rights.
Mitigating Factors for Microsoft Word Malformed Object Pointer Vulnerability - CVE-2006-2492:
* An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
* The vulnerability can not be exploited automatically through e-mail. For an attack to be successful a user must open an attachment that is sent in an e-mail message.
* On Office XP and Office 2003, this vulnerability could not be exploited automatically through a Web-based attack scenario. An attacker would have to host a Web site that contains an Office file that is used to attempt to exploit this vulnerability. An attacker would have no way to force users to visit a malicious Web site. Instead, an attacker would have to persuade them to visit the Web site, typically by getting them to click a link that takes them to the attacker's site.
Note While this vulnerability could not be exploited automatically when visiting a Web site using Word 2000, Office 2000 does not prompt the user to Open, Save, or Cancel before opening a document.
Workarounds for Microsoft Word Code Remote Code Execution Using a Malformed Object Pointer Vulnerability - CVE-2006-2492:
Microsoft has tested the following workarounds. While these workarounds will not correct the underlying vulnerability, they help block known attack vectors. When a workaround reduces functionality, it is identified in the following section.
Always use Microsoft Word in Safe Mode
Using Word in Safe Mode helps protect the affected system from attempts to exploit this vulnerability.
Step 1 - Disable Outlook Feature to Use Word as the E-mail Editor
For Enterprise Customers
Manual (User Interaction)
Enterprise Users follow these steps to disable the Outlook feature to use Word as mail editor:
1. Restart the machine.
2. Open Outlook
3. Click Tools, click Options, and then click the Mail Format tab.
4. Clear the Use Microsoft Word to edit e-mail messages check box.
5. Clear the Use Microsoft Word to read Rich Text e-mail messages box.
6. Exit Outlook.
7. Restart the machine.
For more information on turning Word on or off as your e-mail editor see Turning Word on or off as your e-mail editor.
Impact of Workaround: Users will not be able to use Word as their e-mail editor or use Rich Text to read their e-mail
Using Group Policy
Domain administrators can use Group Policy to disable Word as the users e-mail editor. You do not have to restart the computer to implement this mitigation.
For information on using registry keys with a Group Policy see Using Administrative Template Files with Registry-Based Group Policy and Distributing Registry Changes.
Disable WordMail in Word 2003
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\Options\Mail]
"EditorPreference"=dword:00020000
"UseWordMail"=dword:00000000
Disable WordMail in Word 2002
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Office\10.0\Outlook\Options\Mail]
"EditorPreference"=dword:00020000
"UseWordMail"=dword:00000000
Impact of Workaround: Users will not be able to use Word as their e-mail editor or use Rich Text by default to read their e-mail.
Step 2 Append /safe to the WINWORD.EXE Command Line
For Enterprise Customers
Using Word in Safe Mode helps protect the affected system from attempts to exploit this vulnerability.
All versions of Word have an application recovery feature that allows running Word in Safe mode. Safe mode disables the functionality and prevents vulnerable code from being exploited. The full set of limitations can be found at: http://office.microsoft.com/en-us/assistance/HP030823931033.aspx.
1. Word will display SAFE MODE in the title bar if it is operating in Safe Mode.
2. Right-click your desktop.
3. Select New/Shortcut.
4. Select Browse.
5. Locate winword.exe.
6. Append "/safe" (without quotes) to the end of the file location, after the quotation mark.
7. Click Next, and name your shortcut as Word Safe Mode .
8. Click Finish.
To open a Word document, follow the steps listed below:
1. Save your Word document to a disk or to your desktop.
2. Start Word using your Word Safe Mode shortcut.
3. Click File, click Open, and then browse to the document you want to open.
Impact of Workaround: Users that work in Safe mode will be subject to the limitations outlined in About Office Safe Mode
Enterprise Customers Using Group Policy
Domain administrators can use Group Policy to enable Safe Mode for. You do not have to restart the computer to implement this mitigation.
Note Even after applying the workarounds that implements a registry change, do not open Word files directly from e-mail clients other than Outlook, for example MSN Hotmail, by double-clicking them
For information on using registry keys with a Group Policy see Using Administrative Template Files with Registry-Based Group Policy and Distributing Registry Changes.
Note Exact locations of registry keys depend on installation paths for Office used in each corporation. Registry keys will have to be determined by IT administrators to match their unique installation paths. The locations listed in the examples above correspond to the default installation paths for Microsoft Office. For example the default path for Office 10 on English Windows would be "c:\program files\microsoft office\office10".
Note To ensure Word is being loaded in Safe Mode when opening, editing or printing documents, the Default and Command registry values in the following registry keys should be edited to include the /safe command line parameter (without the quotes).
For example, if Office 2003 is installed the Default value should be changed to look like this: "C:\Program Files\Microsoft Office\OFFICE11\WINWORD.EXE" /n /dde /safe, and the Command value should be changed to look like this: ']gAVn-}f(ZXfeAR6.jiWORDFiles>P`os,1@SW=P7v6GPl]Xh /n /dde /safe .
Note The "Command" value is an encoded string that is version-specific and language-specific, and it may not appear exactly as shown above on all systems.
[HKEY_CLASSES_ROOT\Word.Document.8\shell\Edit\command]
[HKEY_CLASSES_ROOT\Word.Document.8\shell\New\command]
[HKEY_CLASSES_ROOT\Word.Document.8\shell\Open\command]
[HKEY_CLASSES_ROOT\Word.Document.8\shell\OpenAsReadOnly\command]
[HKEY_CLASSES_ROOT\Word.Document.8\shell\Print\command]
[HKEY_CLASSES_ROOT\Word.Document.8\shell\Printto\command]
[HKEY_CLASSES_ROOT\Word.Backup.8\shell\New\command]
[HKEY_CLASSES_ROOT\Word.Backup.8\shell\Open\command]
[HKEY_CLASSES_ROOT\Word.Backup.8\shell\Print\command]
[HKEY_CLASSES_ROOT\Word.Backup.8\shell\Printto\command]
[HKEY_CLASSES_ROOT\Word.RTF.8\shell\Edit\command]
[HKEY_CLASSES_ROOT\Word.RTF.8\shell\New\command]
[HKEY_CLASSES_ROOT\Word.RTF.8\shell\Open\command]
[HKEY_CLASSES_ROOT\Word.RTF.8\shell\Print\command]
[HKEY_CLASSES_ROOT\Word.RTF.8\shell\Printto\command]
[HKEY_CLASSES_ROOT\Word.Template.8\shell\New\command]
[HKEY_CLASSES_ROOT\Word.Template.8\shell\Open\command]
[HKEY_CLASSES_ROOT\Word.Template.8\shell\Print\command]
[HKEY_CLASSES_ROOT\Word.Template.8\shell\Printto\command]
[HKEY_CLASSES_ROOT\Word.Wizard.8\shell\New\command]
Impact of Workaround: Users that work in Safe mode will be subject to the limitations outlined in this online help page: http://office.microsoft.com/en-us/assistance/HP030823931033.aspx
FAQ for Microsoft Word Code Malformed Object Pointer Vulnerability - CVE-2006-2492:
What is the scope of the vulnerability?
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could remotely take complete control of an affected system.
If a user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less affected than users who operate with administrative user rights.
What causes the vulnerability?
When a user opens a specially crafted Word document using a malformed object pointer, it may corrupt system memory in such a way that an attacker could execute arbitrary code.
What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could take complete control of the affected system.
How could an attacker exploit the vulnerability?
In a Web-based attack scenario, an attacker would have to host a Web site that contains an Office file that is used to attempt to exploit this vulnerability. An attacker would have no way to force users to visit a malicious Web site. Instead, an attacker would have to persuade them to visit the Web site, typically by getting them to click a link that takes them to the attacker's site.
In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a specially-crafted file to the user as an attachment and persuading the user to open the attachment.
What systems are primarily at risk from the vulnerability?
Workstations and terminal servers are primarily at risk. Servers could be at more risk if users who do not have sufficient administrative permissions are given the ability to log on to servers and to run programs. However, best practices strongly discourage allowing this.
Could I automatically be exploited when visiting a Web site using Word 2000?
While this vulnerability could not be exploited automatically when visiting a Web site using Word 2000, Office 2000 does not prompt the user to Open, Save, or Cancel before opening a document.
What does the update do?
The update removes the vulnerability by modifying the way that Word validates the length of a message before it to the allocated buffer.
When this security bulletin was issued, had this vulnerability been publicly disclosed?
Yes. While the initial report was provided through responsible disclosure, the vulnerability was later disclosed publicly. This security bulletin addresses the publicly disclosed vulnerability as well as additional issues discovered through internal investigations.
When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
Yes. When the security bulletin was released, Microsoft had received information that this vulnerability was being exploited.
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