Microsoft Security Bulletin MS10-087 - Critical

Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state, that could reduce the severity of exploitation of a vulnerability. The following mitigating factors may be helpful in your situation:

• The vulnerability cannot 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.
• 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.
• In a Web-based attack scenario, an attacker could host a Web site that contains a Web page that is used to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to convince users to visit the Web site, typically by getting them to click a link in an e-mail message or Instant Messenger message that takes users to the attacker’s Web site, and then convince them to open the specially crafted PowerPoint file.

Workaround refers to a setting or configuration change that does not correct the underlying vulnerability but would help block known attack vectors before you apply the update. Microsoft has tested the following workarounds and states in the discussion whether a workaround reduces functionality:

• Use Microsoft Office File Block policy to block the opening of Office 2003 and earlier documents from unknown or untrusted sources and locations

  The following registry scripts can be used to set the File Block policy.

  Note Modifying the Registry incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from incorrect modification of the Registry can be solved. Modify the Registry at your own risk.

  For Office 2003 
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\PowerPoint\Security\FileOpenBlock]

"BinaryFiles"=dword:00000001
  
  Note In order to use 'FileOpenBlock' with Microsoft Office 2003, all of the latest security updates for Microsoft Office 2003 must be applied.

  Alternatively, file block can be applied using Group Policy. For more information, see the TechNet article, Plan file block settings for Office 2010.

  Impact of workaround. For Microsoft Office 2003 and Microsoft Office 2007, users who have configured the File Block policy and have not configured a special "exempt directory" as discussed in Microsoft Knowledge Base Article 922848 will be unable to open Office 2003 files or earlier versions. For Microsoft Office 2007, Office 2003 or earlier versions will either be blocked from opening or will be opened in protected mode depending on the open behavior that was selected.

  How to undo the workaround.

  For Office 2003
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\PowerPoint\Security\FileOpenBlock]

"BinaryFiles"=dword:00000000

• Use the Microsoft Office Isolated Conversion Environment (MOICE) when opening files from unknown or untrusted sources

  The Microsoft Office Isolated Conversion Environment (MOICE) helps protect Office 2003 installations by more securely opening Word, Excel, and PowerPoint binary format files.

  To install MOICE, you must have Office 2003 or Office 2007 installed.

  To install MOICE, you must also have the Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats. The compatibility pack is available as a free download from the Microsoft Download Center.

  MOICE requires all updates that are recommended for all Office programs. Visit Microsoft Update to install all recommended updates.

  Enable MOICE

  Note See Microsoft Knowledge Base Article 935865 to use the automated Microsoft Fix it solution to enable or disable this workaround.

  To manually enable MOICE, run the commands as specified in the following table. Running the commands will associate the Office application extensions with MOICE.

Note On Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2, run the above commands from an elevated command prompt.

For more information on MOICE, see Microsoft Knowledge Base Article 935865.

Impact of workaround. Office 2003 and earlier formatted documents that are converted to the Microsoft Office 2007 Open XML format by MOICE will not retain macro functionality. Additionally, documents with passwords or that are protected with Digital Rights Management cannot be converted.

How to undo the workaround. Run the commands to disable MOICE as specified in the table below.

Note On Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2, run the above commands from an elevated command prompt.

• Do not open PowerPoint files from untrusted sources

  Do not open or save PowerPoint files that you receive from untrusted sources or that you receive unexpectedly from trusted sources. This vulnerability could be exploited when a user opens a specially crafted file.

What is the scope of the vulnerability? 
This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could take complete control of an affected system remotely. An attacker could then install programs or view, change, or delete data; or create new accounts with full user rights.

What causes the vulnerability? 
The vulnerability exists because of the way that Microsoft PowerPoint parses the PowerPoint file format when opening a specially crafted PowerPoint file.

What might an attacker use the vulnerability to do? 
An attacker who successfully exploited this vulnerability could run arbitrary code as the logged-on user. If a user is logged on with administrative user rights, an attacker could take complete control of the 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 impacted than users who operate with administrative user rights.

How could an attacker exploit the vulnerability? 
The vulnerability exists because of the way that Microsoft PowerPoint parses the PowerPoint file format when opening a specially crafted PowerPoint file.

In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a specially crafted PowerPoint file to the user and by convincing the user to open the file.

In a Web-based attack scenario, an attacker would have to host a Web site that contains a PowerPoint file that is used to attempt to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content could contain specially crafted content that could exploit this vulnerability. An attacker would have no way to force users to visit a specially crafted Web site. Instead, an attacker would have to convince them to visit the Web site, typically by getting them to click a link that takes them to the attacker's site, and then convince them to open the specially crafted PowerPoint file.

What systems are primarily at risk from the vulnerability? 
Systems where Microsoft PowerPoint is used, including workstations and terminal servers, are primarily at risk. Servers could be at more risk if administrators allow users to log on to servers and to run programs. However, best practices strongly discourage allowing this.

What does the update do? 
This update addresses the vulnerability by changing the way that Microsoft PowerPoint parses specially crafted PowerPoint files.

When this security bulletin was issued, had this vulnerability been publicly disclosed? 
No. Microsoft received information about this vulnerability through coordinated vulnerability disclosure.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited? 
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.

Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state, that could reduce the severity of exploitation of a vulnerability. The following mitigating factors may be helpful in your situation:

• An attacker who successfully exploited this vulnerability could gain the same user rights as the logged-on 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.
• In a Web-based attack scenario, an attacker could host a Web site that contains a Web page that is used to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to convince users to visit the Web site, typically by getting them to click a link in an e-mail message or Instant Messenger message that takes users to the attacker’s Web site, and then convince them to open the specially crafted Office file.

Workaround refers to a setting or configuration change that does not correct the underlying vulnerability but would help block known attack vectors before you apply the update. Microsoft has tested the following workarounds and states in the discussion whether a workaround reduces functionality:

• Read e-mails in plain text

  To help protect yourself from the e-mail attack vector, read e-mail messages in plain text format.

  Microsoft Office Outlook 2002 users who have applied Office XP Service Pack 1 or a later version can enable this setting and view in plain text only those e-mail messages that are not digitally signed or e-mail messages that are not encrypted.

  Digitally signed e-mail messages or encrypted e-mail messages are not affected by the setting and may be read in their original formats. For more information about how to enable this setting in Outlook 2002, see Microsoft Knowledge Base Article 307594.

  Impact of workaround. E-mail messages that are viewed in plain text format will not contain pictures, specialized fonts, animations, or other rich content. Additionally:

  • The changes are applied to the preview pane and to open messages.
  • Pictures become attachments so that they are not lost.
  • Because the message is still in Rich Text or HTML format in the store, the object model (custom code solutions) may behave unexpectedly.
• Use Microsoft Office File Block policy to block the opening of RTF documents from unknown or untrusted sources and locations

  The following registry scripts can be used to set the File Block policy.

  Note Modifying the Registry incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from incorrect modification of the Registry can be solved. Modify the Registry at your own risk.

  For Office 2003 
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Word\Security\FileOpenBlock]

"RtfFiles"=dword:00000001
  
  Note In order to use 'FileOpenBlock' with Microsoft Office 2003, all of the latest security updates for Microsoft Office 2003 must be applied.

  For Office 2007 
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Word\Security\FileOpenBlock]

"RtfFiles"=dword:00000001
  
  Note In order to use 'FileOpenBlock' with Microsoft Office 2007, all of the latest security updates for Microsoft Office 2007 must be applied.

  For Office 2010 
  
  Open Word 2010 and follow the steps below:

  1. Click the File tab.
  2. Under Help, click Options.
  3. Click Trust Center, and then click Trust Center Settings.
  4. In the Trust Center, click File Block Settings.
  5. Ensure the Open check box is selected for the following file types:
     - RTF Files
  6. Under Open behavior for selected file types, select "Do not open selected file types" or select "Open selected file types in Protected View". Either choice will block the attack vector to the vulnerable code.
  7. Click OK to apply the File Block Settings.

  Alternatively, file block can be applied using Group Policy. For more information, see the TechNet article, Plan file block settings for Office 2010.

  Impact of workaround. Users who have configured the File Block policy and have not configured a special exempt directory or have not moved files to a trusted location as discussed in Microsoft Knowledge Base Article 922848 will be unable to open RTF files in Office 2003 or 2007 Microsoft Office System. For Microsoft Office 2010, RTF files will either be blocked from opening or will be opened in protected mode depending on the open behavior that was selected.

  How to undo the workaround.

  For Office 2003
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Word\Security\FileOpenBlock]

"RtfFiles"=dword:00000000

  For 2007 Office system
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Word\Security\FileOpenBlock]

"RtfFiles"=dword:00000000

  For Office 2010 
  
  Open Word 2010 and follow these steps:

  1. Click the File tab.
  2. Under Help, click Options.
  3. Click Trust Center, and then click Trust Center Settings.
  4. In the Trust Center, click File Block Settings.
  5. Clear the Open check box for the file types that you previously selected.
  6. Click OK to apply the File Block settings.

What is the scope of the vulnerability? 
This is a remote code execution vulnerability. 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.

What causes the vulnerability? 
When Microsoft Office software parses specially crafted RTF-formatted data, system memory may be corrupted in such a way that an attacker could execute arbitrary code.

What is RTF? 
Rich Text Format (RTF) is a method of encoding formatted text and graphics for use within applications and for transfer between applications. Users often depend on special translation software to move word-processing documents between various applications developed by different companies. RTF serves as both a standard of data transfer between word processing software, document formatting, and a means of migrating content from one operating system to another.

What might an attacker use the vulnerability to do? 
An attacker who successfully exploited this vulnerability could cause arbitrary code to run with the privileges of the user who opens a specially crafted RTF file or previews or opens a specially crafted RTF e-mail message. If the 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 impacted than users who operate with administrative user rights.

How could an attacker exploit the vulnerability? 
This vulnerability requires that a user open or preview specially crafted RTF-formatted data with an affected version of Microsoft Office software.

In an e-mail attack scenario, an attacker could exploit the vulnerability by sending specially-crafted RTF-formatted data in the contents of an e-mail message. The vulnerability could be exploited when the specially crafted RTF e-mail message is previewed or opened in Outlook while using Word as the e-mail viewer. An attacker could also exploit the vulnerability by sending a specially-crafted RTF file as an attachment and convincing the user to open the specially crafted RTF file.

In a Web-based attack scenario, an attacker could host a Web site that contains an Office file that is used to attempt to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content could contain specially crafted content that could exploit this vulnerability. An attacker would have no way to force users to visit a specially crafted Web site. Instead, an attacker would have to convince them to visit the Web site, typically by getting them to click a link that takes them to the attacker's site, and then convince them to open the specially crafted Office file.

How is Microsoft Office affected by this vulnerability? 
Although the known attack vectors can only leverage Microsoft Word, the vulnerable code exists in a shared component of Microsoft Office.

What systems are primarily at risk from the vulnerability? 
Systems where Microsoft Office software is used, including workstations and terminal servers, are primarily at risk. Servers could be at more risk if administrators allow users to log on to servers and to run programs. However, best practices strongly discourage allowing this.

What does the update do? 
The update addresses the vulnerability by modifying the way that Microsoft Office parses RTF-formatted data.

When this security bulletin was issued, had this vulnerability been publicly disclosed? 
No. Microsoft received information about this vulnerability through coordinated vulnerability disclosure.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited? 
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.

Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state, that could reduce the severity of exploitation of a vulnerability. The following mitigating factors may be helpful in your situation:

• The vulnerability cannot 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.
• 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.
• In a Web-based attack scenario, an attacker could host a Web site that contains a Web page that is used to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to convince users to visit the Web site, typically by getting them to click a link in an e-mail message or Instant Messenger message that takes users to the attacker’s Web site, and then convince them to open the specially crafted Office file.

Workaround refers to a setting or configuration change that does not correct the underlying vulnerability but would help block known attack vectors before you apply the update. Microsoft has tested the following workarounds and states in the discussion whether a workaround reduces functionality:

• Use Microsoft Office File Block policy to block the opening of Office 2003 and earlier documents in Microsoft Word from unknown or untrusted sources and locations

  The following registry scripts can be used to set the File Block policy.

  Note Modifying the Registry incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from incorrect modification of the Registry can be solved. Modify the Registry at your own risk.

  For Office 2003 
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Word\Security\FileOpenBlock]

"BinaryFiles"=dword:00000001
  
  Note In order to use 'FileOpenBlock' with Microsoft Office 2003, all of the latest security updates for Microsoft Office 2003 must be applied.

  For Office 2007 
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Word\Security\FileOpenBlock]

"BinaryFiles"=dword:00000001
  
  Note In order to use 'FileOpenBlock' with Office 2007, all of the latest security updates for Microsoft Office 2007 must be applied.

  For Office 2010 
  
  Open Word 2010 and follow the steps below:

  1. Click the File tab.
  2. Under Help, click Options.
  3. Click Trust Center, and then click Trust Center Settings.
  4. In the Trust Center, click File Block Settings.
  5. Ensure the Open check box is selected for the following file types:
     - Word 2003 Binary Documents and Templates
     - Word XP Binary Documents and Templates
     - Word 2000 Binary Documents and Templates
     - Word 97 Binary Documents and Templates
     - Word 95 Binary Documents and Templates
     - Word 6.0 Binary Documents and Templates
     - Word 2 and earlier Binary Documents and Templates
  6. Under Open behavior for selected file types, select "Do not open selected file types" or select "Open selected file types in Protected View". Either choice will block the attack vector to the vulnerable code.
  7. Click OK to apply the File Block Settings.

  Alternatively, file block can be applied using Group Policy. For more information, see the TechNet article, Plan file block settings for Office 2010.

  Impact of workaround. For Microsoft Office 2003 and Microsoft Office 2007, users who have configured the File Block policy and have not configured a special exempt directory or have not moved files to a trusted location as discussed in Microsoft Knowledge Base Article 922848 will be unable to open Office 2003 files or earlier versions. For Microsoft Office 2010, Office 2003 files or earlier versions will either be blocked from opening or will be opened in protected mode depending on the open behavior that was selected.

  How to undo the workaround.

  For Office 2003
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Word\Security\FileOpenBlock]

"BinaryFiles"=dword:00000000

  For Office 2007
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Word\Security\FileOpenBlock]

"BinaryFiles"=dword:00000000

  For Office 2010 
  
  Open Word 2010 and follow these steps:

  1. Click the File tab.
  2. Under Help, click Options.
  3. Click Trust Center, and then click Trust Center Settings.
  4. In the Trust Center, click File Block Settings.
  5. Clear the Open check box for the file types that you previously selected.
  6. Click OK to apply the File Block settings.
• Use Microsoft Office File Block policy to block the opening of Office 2003 and earlier documents in Microsoft Excel from unknown or untrusted sources and locations

  The following registry scripts can be used to set the File Block policy.

  Note Modifying the Registry incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from incorrect modification of the Registry can be solved. Modify the Registry at your own risk.

  For Office 2003 
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Excel\Security\FileOpenBlock]

"BinaryFiles"=dword:00000001
  
  Note In order to use 'FileOpenBlock' with Microsoft Office 2003, all of the latest security updates for Microsoft Office 2003 must be applied.

  For Office 2007 
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Excel\Security\FileOpenBlock]

"BinaryFiles"=dword:00000001
  
  Note In order to use 'FileOpenBlock' with Microsoft Office 2007, all of the latest security updates for Office 2007 must be applied.

  For Office 2010 
  
  Open Excel 2010 and follow the steps below:

  1. Click the File tab.
  2. Under Help, click Options.
  3. Click Trust Center, and then click Trust Center Settings.
  4. In the Trust Center, click File Block Settings.
  5. Ensure the Open check box is selected for the following file types:
     - Excel 2007 and later Binary Workbooks
     - Excel 97-2003 Add-in Files
     - Excel 97-2003 Workbooks and Templates
     - Excel 95-97 Workbooks and Templates
     - Excel 95 Workbooks
     - Excel 4 Workbooks
     - Excel 4 Worksheets
     - Excel 3 Worksheets
     - Excel 2 Worksheets
  6. Under Open behavior for selected file types, select "Do not open selected file types" or select "Open selected file types in Protected View". Either choice will block the attack vector to the vulnerable code.
  7. Click OK to apply the File Block Settings.

  Alternatively, file block can be applied using Group Policy. For more information, see the TechNet article, Plan file block settings for Office 2010.

  Impact of workaround. For Microsoft Office 2003 and Microsoft Office 2007, users who have configured the File Block policy and have not configured a special exempt directory or have not moved files to a trusted location as discussed in Microsoft Knowledge Base Article 922848 will be unable to open Office 2003 files or earlier versions. For Microsoft Office 2010, Office 2003 files or earlier versions will either be blocked from opening or will be opened in protected mode depending on the open behavior that was selected.

  How to undo the workaround.

  For Office 2003
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Excel\Security\FileOpenBlock]

"BinaryFiles"=dword:00000000

  For Office 2007
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Excel\Security\FileOpenBlock]

"BinaryFiles"=dword:00000000

  For Office 2010 
  
  Open Excel 2010 and follow these steps:

  1. Click the File tab.
  2. Under Help, click Options.
  3. Click Trust Center, and then click Trust Center Settings.
  4. In the Trust Center, click File Block Settings.
  5. Clear the Open check box for the file types that you previously selected.
  6. Click OK to apply the File Block settings.
• Use Microsoft Office File Block policy to block the opening of Office 2003 and earlier documents in Microsoft PowerPoint from unknown or untrusted sources and locations

  The following registry scripts can be used to set the File Block policy.

  Note Modifying the Registry incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from incorrect modification of the Registry can be solved. Modify the Registry at your own risk.

  For Office 2003 
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\PowerPoint\Security\FileOpenBlock]

"BinaryFiles"=dword:00000001
  
  Note In order to use 'FileOpenBlock' with Microsoft Office 2003, all of the latest security updates for Microsoft Office 2003 must be applied.

  For Office 2007 
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\PowerPoint\Security\FileOpenBlock]

"BinaryFiles"=dword:00000001
  
  Note In order to use 'FileOpenBlock' with the 2007 Microsoft Office system, all of the latest security updates for the 2007 Microsoft Office system must be applied.

  For Office 2010 
  
  Open PowerPoint 2010 and follow the steps below:

  1. Click the File tab.
  2. Under Help, click Options.
  3. Click Trust Center, and then click Trust Center Settings.
  4. In the Trust Center, click File Block Settings.
  5. Ensure the Open check box is selected for the following file types:
     - PowerPoint 97-2003 Presentations, Shows, Templates and Add-in Files
  6. Under Open behavior for selected file types, select "Do not open selected file types" or select "Open selected file types in Protected View". Either choice will block the attack vector to the vulnerable code.
  7. Click OK to apply the File Block Settings.

  Alternatively, file block can be applied using Group Policy. For more information, see the TechNet article, Plan file block settings for Office 2010.

  Impact of workaround. For Microsoft Office 2003 and Microsoft Office 2007, users who have configured the File Block policy and have not configured a special exempt directory or have not moved files to a trusted location as discussed in Microsoft Knowledge Base Article 922848 will be unable to open Office 2003 files or earlier versions. For Microsoft Office 2010, Office 2003 files or earlier versions will either be blocked from opening or will be opened in protected mode depending on the open behavior that was selected.

  How to undo the workaround.

  For Office 2003
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\PowerPoint\Security\FileOpenBlock]

"BinaryFiles"=dword:00000000

  For Office 2007
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\PowerPoint\Security\FileOpenBlock]

"BinaryFiles"=dword:00000000

  For Office 2010 
  
  Open PowerPoint 2010 and follow these steps:

  1. Click the File tab.
  2. Under Help, click Options.
  3. Click Trust Center, and then click Trust Center Settings.
  4. In the Trust Center, click File Block Settings.
  5. Clear the Open check box for the file types that you previously selected.
  6. Click OK to apply the File Block settings.
• Use the Microsoft Office Isolated Conversion Environment (MOICE) when opening files from unknown or untrusted sources

  The Microsoft Office Isolated Conversion Environment (MOICE) helps protect Office 2003 installations by more securely opening Word, Excel, and PowerPoint binary format files.

  To install MOICE, you must have Office 2003 or Office 2007 installed.

  To install MOICE, you must also have the Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats. The compatibility pack is available as a free download from the Microsoft Download Center.

  MOICE requires all updates that are recommended for all Office programs. Visit Microsoft Update to install all recommended updates.

  Enable MOICE

  Note See Microsoft Knowledge Base Article 935865 to use the automated Microsoft Fix it solution to enable or disable this workaround.

  To manually enable MOICE, run the commands as specified in the following table. Running the commands will associate the Office application extensions with MOICE.

Note On Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2, run the above commands from an elevated command prompt.

For more information on MOICE, see Microsoft Knowledge Base Article 935865.

Impact of workaround. Office 2003 and earlier formatted documents that are converted to the Microsoft Office 2007 Open XML format by MOICE will not retain macro functionality. Additionally, documents with passwords or that are protected with Digital Rights Management cannot be converted.

How to undo the workaround. Run the commands to disable MOICE as specified in the table below.

Note On Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2, run the above commands from an elevated command prompt.

• Do not open Office files that you receive from untrusted sources or that you receive unexpectedly from trusted sources

  Do not open Office files that you receive from untrusted sources or that you receive unexpectedly from trusted sources. This vulnerability could be exploited when a user opens a specially crafted file.

What is the scope of the vulnerability? 
This is a remote code execution vulnerability. 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.

What causes the vulnerability? 
When a user opens a specially crafted Office file, system memory may become corrupted 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 run arbitrary code as the logged-on user. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. If a user is logged-on with administrative user rights, an attacker could take complete control of the affected system. 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.

How could an attacker exploit the vulnerability? 
This vulnerability requires that a user open a specially crafted Office file with an affected version of Microsoft Office software.

In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a specially crafted Office file to the user and by convincing the user to open the file.

In a Web-based attack scenario, an attacker could host a Web site that contains an Office file that is used to attempt to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content could contain specially crafted content that could exploit this vulnerability. An attacker would have no way to force users to visit a specially crafted Web site. Instead, an attacker would have to convince them to visit the Web site, typically by getting them to click a link that takes them to the attacker's site, and then convince them to open the specially crafted Office file.

What systems are primarily at risk from the vulnerability? 
Systems where Microsoft Office software is used, including workstations and terminal servers, are primarily at risk. Servers could be at more risk if administrators allow users to log on to servers and to run programs. However, best practices strongly discourage allowing this.

What does the update do? 
The update addresses the vulnerability by modifying the way that Microsoft Office software parses files.

When this security bulletin was issued, had this vulnerability been publicly disclosed? 
No. Microsoft received information about this vulnerability through coordinated vulnerability disclosure.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited? 
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.

Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state, that could reduce the severity of exploitation of a vulnerability. The following mitigating factors may be helpful in your situation:

• The vulnerability cannot 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.
• 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.
• In a Web-based attack scenario, an attacker could host a Web site that contains a Web page that is used to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to convince users to visit the Web site, typically by getting them to click a link in an e-mail message or Instant Messenger message that takes users to the attacker’s Web site, and then convince them to open the specially crafted Office file.

Workaround refers to a setting or configuration change that does not correct the underlying vulnerability but would help block known attack vectors before you apply the update. Microsoft has tested the following workarounds and states in the discussion whether a workaround reduces functionality:

• Use Microsoft Office File Block policy to block the opening of Office 2003 and earlier documents in Microsoft Word from unknown or untrusted sources and locations

  The following registry scripts can be used to set the File Block policy.

  Note Modifying the Registry incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from incorrect modification of the Registry can be solved. Modify the Registry at your own risk.

  For Office 2003 
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Word\Security\FileOpenBlock]

"BinaryFiles"=dword:00000001
  
  Note In order to use 'FileOpenBlock' with Microsoft Office 2003, all of the latest security updates for Microsoft Office 2003 must be applied.

  For Office 2007 
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Word\Security\FileOpenBlock]

"BinaryFiles"=dword:00000001
  
  Note In order to use 'FileOpenBlock' with Office 2007, all of the latest security updates for Microsoft Office 2007 must be applied.

  For Office 2010 
  
  Open Word 2010 and follow the steps below:

  1. Click the File tab.
  2. Under Help, click Options.
  3. Click Trust Center, and then click Trust Center Settings.
  4. In the Trust Center, click File Block Settings.
  5. Ensure the Open check box is selected for the following file types:
     - Word 2003 Binary Documents and Templates
     - Word XP Binary Documents and Templates
     - Word 2000 Binary Documents and Templates
     - Word 97 Binary Documents and Templates
     - Word 95 Binary Documents and Templates
     - Word 6.0 Binary Documents and Templates
     - Word 2 and earlier Binary Documents and Templates
  6. Under Open behavior for selected file types, select "Do not open selected file types" or select "Open selected file types in Protected View". Either choice will block the attack vector to the vulnerable code.
  7. Click OK to apply the File Block Settings.

  Alternatively, file block can be applied using Group Policy. For more information, see the TechNet article, Plan file block settings for Office 2010.

  Impact of workaround. For Microsoft Office 2003 and Microsoft Office 2007, users who have configured the File Block policy and have not configured a special exempt directory or have not moved files to a trusted location as discussed in Microsoft Knowledge Base Article 922848 will be unable to open Office 2003 files or earlier versions. For Microsoft Office 2010, Office 2003 files or earlier versions will either be blocked from opening or will be opened in protected mode depending on the open behavior that was selected.

  How to undo the workaround.

  For Office 2003
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Word\Security\FileOpenBlock]

"BinaryFiles"=dword:00000000

  For Office 2007
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Word\Security\FileOpenBlock]

"BinaryFiles"=dword:00000000

  For Office 2010 
  
  Open Word 2010 and follow these steps:

  1. Click the File tab.
  2. Under Help, click Options.
  3. Click Trust Center, and then click Trust Center Settings.
  4. In the Trust Center, click File Block Settings.
  5. Clear the Open check box for the file types that you previously selected.
  6. Click OK to apply the File Block settings.
• Use Microsoft Office File Block policy to block the opening of Office 2003 and earlier documents in Microsoft Excel from unknown or untrusted sources and locations

  The following registry scripts can be used to set the File Block policy.

  Note Modifying the Registry incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from incorrect modification of the Registry can be solved. Modify the Registry at your own risk.

  For Office 2003 
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Excel\Security\FileOpenBlock]

"BinaryFiles"=dword:00000001
  
  Note In order to use 'FileOpenBlock' with Microsoft Office 2003, all of the latest security updates for Microsoft Office 2003 must be applied.

  For Office 2007 
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Excel\Security\FileOpenBlock]

"BinaryFiles"=dword:00000001
  
  Note In order to use 'FileOpenBlock' with Microsoft Office 2007, all of the latest security updates for Office 2007 must be applied.

  For Office 2010 
  
  Open Excel 2010 and follow the steps below:

  1. Click the File tab.
  2. Under Help, click Options.
  3. Click Trust Center, and then click Trust Center Settings.
  4. In the Trust Center, click File Block Settings.
  5. Ensure the Open check box is selected for the following file types:
     - Excel 2007 and later Binary Workbooks
     - Excel 97-2003 Add-in Files
     - Excel 97-2003 Workbooks and Templates
     - Excel 95-97 Workbooks and Templates
     - Excel 95 Workbooks
     - Excel 4 Workbooks
     - Excel 4 Worksheets
     - Excel 3 Worksheets
     - Excel 2 Worksheets
  6. Under Open behavior for selected file types, select "Do not open selected file types" or select "Open selected file types in Protected View". Either choice will block the attack vector to the vulnerable code.
  7. Click OK to apply the File Block Settings.

  Alternatively, file block can be applied using Group Policy. For more information, see the TechNet article, Plan file block settings for Office 2010.

  Impact of workaround. For Microsoft Office 2003 and Microsoft Office 2007, users who have configured the File Block policy and have not configured a special exempt directory or have not moved files to a trusted location as discussed in Microsoft Knowledge Base Article 922848 will be unable to open Office 2003 files or earlier versions. For Microsoft Office 2010, Office 2003 files or earlier versions will either be blocked from opening or will be opened in protected mode depending on the open behavior that was selected.

  How to undo the workaround.

  For Office 2003
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Excel\Security\FileOpenBlock]

"BinaryFiles"=dword:00000000

  For Office 2007
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Excel\Security\FileOpenBlock]

"BinaryFiles"=dword:00000000

  For Office 2010 
  
  Open Excel 2010 and follow these steps:

  1. Click the File tab.
  2. Under Help, click Options.
  3. Click Trust Center, and then click Trust Center Settings.
  4. In the Trust Center, click File Block Settings.
  5. Clear the Open check box for the file types that you previously selected.
  6. Click OK to apply the File Block settings.
• Use Microsoft Office File Block policy to block the opening of Office 2003 and earlier documents in Microsoft PowerPoint from unknown or untrusted sources and locations

  The following registry scripts can be used to set the File Block policy.

  Note Modifying the Registry incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from incorrect modification of the Registry can be solved. Modify the Registry at your own risk.

  For Office 2003 
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\PowerPoint\Security\FileOpenBlock]

"BinaryFiles"=dword:00000001
  
  Note In order to use 'FileOpenBlock' with Microsoft Office 2003, all of the latest security updates for Microsoft Office 2003 must be applied.

  For Office 2007 
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\PowerPoint\Security\FileOpenBlock]

"BinaryFiles"=dword:00000001
  
  Note In order to use 'FileOpenBlock' with the 2007 Microsoft Office system, all of the latest security updates for the 2007 Microsoft Office system must be applied.

  For Office 2010 
  
  Open PowerPoint 2010 and follow the steps below:

  1. Click the File tab.
  2. Under Help, click Options.
  3. Click Trust Center, and then click Trust Center Settings.
  4. In the Trust Center, click File Block Settings.
  5. Ensure the Open check box is selected for the following file types:
     - PowerPoint 97-2003 Presentations, Shows, Templates and Add-in Files
  6. Under Open behavior for selected file types, select "Do not open selected file types" or select "Open selected file types in Protected View". Either choice will block the attack vector to the vulnerable code.
  7. Click OK to apply the File Block Settings.

  Alternatively, file block can be applied using Group Policy. For more information, see the TechNet article, Plan file block settings for Office 2010.

  Impact of workaround. For Microsoft Office 2003 and Microsoft Office 2007, users who have configured the File Block policy and have not configured a special exempt directory or have not moved files to a trusted location as discussed in Microsoft Knowledge Base Article 922848 will be unable to open Office 2003 files or earlier versions. For Microsoft Office 2010, Office 2003 files or earlier versions will either be blocked from opening or will be opened in protected mode depending on the open behavior that was selected.

  How to undo the workaround.

  For Office 2003
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\PowerPoint\Security\FileOpenBlock]

"BinaryFiles"=dword:00000000

  For Office 2007
  
  Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\PowerPoint\Security\FileOpenBlock]

"BinaryFiles"=dword:00000000

  For Office 2010 
  
  Open PowerPoint 2010 and follow these steps:

  1. Click the File tab.
  2. Under Help, click Options.
  3. Click Trust Center, and then click Trust Center Settings.
  4. In the Trust Center, click File Block Settings.
  5. Clear the Open check box for the file types that you previously selected.
  6. Click OK to apply the File Block settings.
• Use the Microsoft Office Isolated Conversion Environment (MOICE) when opening files from unknown or untrusted sources

  The Microsoft Office Isolated Conversion Environment (MOICE) helps protect Office 2003 installations by more securely opening Word, Excel, and PowerPoint binary format files.

  To install MOICE, you must have Office 2003 or Office 2007 installed.

  To install MOICE, you must also have the Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats. The compatibility pack is available as a free download from the Microsoft Download Center.

  MOICE requires all updates that are recommended for all Office programs. Visit Microsoft Update to install all recommended updates.

  Enable MOICE

  Note See Microsoft Knowledge Base Article 935865 to use the automated Microsoft Fix it solution to enable or disable this workaround.

  To manually enable MOICE, run the commands as specified in the following table. Running the commands will associate the Office application extensions with MOICE.

Note On Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2, run the above commands from an elevated command prompt.

For more information on MOICE, see Microsoft Knowledge Base Article 935865.

Impact of workaround. Office 2003 and earlier formatted documents that are converted to the Microsoft Office 2007 Open XML format by MOICE will not retain macro functionality. Additionally, documents with passwords or that are protected with Digital Rights Management cannot be converted.

How to undo the workaround. Run the commands to disable MOICE as specified in the table below.

Note On Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2, run the above commands from an elevated command prompt.

• Do not open Office files that you receive from untrusted sources or that you receive unexpectedly from trusted sources

  Do not open Office files that you receive from untrusted sources or that you receive unexpectedly from trusted sources. This vulnerability could be exploited when a user opens a specially crafted file.

What is the scope of the vulnerability? 
This is a remote code execution vulnerability. 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.

What causes the vulnerability? 
When a user opens a specially crafted Office file, system memory may become corrupted 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 run arbitrary code as the logged-on user. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. If a user is logged-on with administrative user rights, an attacker could take complete control of the affected system. 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.

How could an attacker exploit the vulnerability? 
This vulnerability requires that a user open a specially crafted Office file with an affected version of Microsoft Office software.

In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a specially crafted Office file to the user and by convincing the user to open the file.

In a Web-based attack scenario, an attacker could host a Web site that contains an Office file that is used to attempt to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content could contain specially crafted content that could exploit this vulnerability. An attacker would have no way to force users to visit a specially crafted Web site. Instead, an attacker would have to convince them to visit the Web site, typically by getting them to click a link that takes them to the attacker's site, and then convince them to open the specially crafted Office file.

What systems are primarily at risk from the vulnerability? 
Systems where Microsoft Office software is used, including workstations and terminal servers, are primarily at risk. Servers could be at more risk if administrators allow users to log on to servers and to run programs. However, best practices strongly discourage allowing this.

What does the update do? 
The update addresses the vulnerability by modifying the way that Microsoft Office parses Office files.

When this security bulletin was issued, had this vulnerability been publicly disclosed? 
No. Microsoft received information about this vulnerability through coordinated vulnerability disclosure.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited? 
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.

Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state, that could reduce the severity of exploitation of a vulnerability. The following mitigating factors may be helpful in your situation:

• The vulnerability cannot 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.
• 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.
• In a Web-based attack scenario, an attacker could host a Web site that contains a Web page that is used to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to convince users to visit the Web site, typically by getting them to click a link in an e-mail message or Instant Messenger message that takes users to the attacker’s Web site, and then convince them to open the specially crafted Office file.

Workaround refers to a setting or configuration change that does not correct the underlying vulnerability but would help block known attack vectors before you apply the update. Microsoft has tested the following workarounds and states in the discussion whether a workaround reduces functionality:

• Do not open Office files that you receive from untrusted sources or that you receive unexpectedly from trusted sources

  Do not open Office files that you receive from untrusted sources or that you receive unexpectedly from trusted sources. This vulnerability could be exploited when a user opens a specially crafted file.

What is the scope of the vulnerability? 
This is a remote code execution vulnerability. 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.

What causes the vulnerability? 
When a user opens a specially crafted Office file, system memory may become corrupted 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 run arbitrary code as the logged-on user. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. If a user is logged-on with administrative user rights, an attacker could take complete control of the affected system. 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.

How could an attacker exploit the vulnerability? 
This vulnerability requires that a user open a specially crafted Office file with an affected version of Microsoft Office software.

In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a specially crafted Office file to the user and by convincing the user to open the file.

In a Web-based attack scenario, an attacker could host a Web site that contains an Office file that is used to attempt to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content could contain specially crafted content that could exploit this vulnerability. An attacker would have no way to force users to visit a specially crafted Web site. Instead, an attacker would have to convince them to visit the Web site, typically by getting them to click a link that takes them to the attacker's site, and then convince them to open the specially crafted Office file.

What systems are primarily at risk from the vulnerability? 
Systems where Microsoft Office software is used, including workstations and terminal servers, are primarily at risk. Servers could be at more risk if administrators allow users to log on to servers and to run programs. However, best practices strongly discourage allowing this.

What does the update do? 
The update addresses the vulnerability by modifying the way that Microsoft Office parses files.

When this security bulletin was issued, had this vulnerability been publicly disclosed? 
No. Microsoft received information about this vulnerability through coordinated vulnerability disclosure.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited? 
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.

Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state, that could reduce the severity of exploitation of a vulnerability. The following mitigating factors may be helpful in your situation:

• For an attack to be successful using an untrusted remote file system location or WebDAV share, a user must be convinced to open a PowerPoint presentation located on the remote file system location or WebDAV share. An attacker would have no way to force users to visit an untrusted remote file system location or WebDAV share. Instead, an attacker would have to convince them to visit the untrusted remote file system location or WebDAV share, typically by getting them to click a link in an e-mail message or Instant Messenger message that takes them to the untrusted remote file system location or WebDAV share.
• The file sharing protocol SMB is often disabled on the perimeter firewall. This limits the potential attack vectors.

Workaround refers to a setting or configuration change that does not correct the underlying vulnerability but would help block known attack vectors before you apply the update. Microsoft has tested the following workarounds and states in the discussion whether a workaround reduces functionality:

• Disable loading of libraries from WebDAV and remote network shares

  Note See Microsoft Knowledge Base Article 2264107 to deploy a workaround tool that allows customers to disable the loading of libraries from remote network or WebDAV shares. This tool can be configured to disallow insecure loading on a per-application or a global system basis.

  Customers who are informed by their vendor of an application being vulnerable can use this tool to help protect against attempts to exploit this issue.

  Note See Microsoft Knowledge Base Article 2264107 to use the automated Microsoft Fix it solution to deploy the registry key to block loading of libraries for SMB and WebDAV shares. Note that this Fix it solution does require you to install the workaround tool also described in Microsoft Knowledge Base Article 2264107 first. This Fix it solution only deploys the registry key and requires the workaround tool in order to be effective. We recommend that administrators review the KB article closely prior to deploying this Fix it solution.

• Disable the WebClient service

  Disabling the WebClient service helps protect affected systems from attempts to exploit this vulnerability by blocking the most likely remote attack vector through the Web Distributed Authoring and Versioning (WebDAV) client service. After applying this workaround it is still possible for remote attackers who successfully exploit this vulnerability to cause Microsoft Office Outlook to run programs located on the targeted user's computer or the Local Area Network (LAN), but users will be prompted for confirmation before opening arbitrary programs from the Internet.

  To disable the WebClient Service, follow these steps:

  1. Click Start, click Run, type Services.msc and then click OK.
  2. Right-click WebClient service and select Properties.
  3. Change the Startup type to Disabled. If the service is running, click Stop.
  4. Click OK and exit the management application.

  Impact of workaround. When the WebClient service is disabled, Web Distributed Authoring and Versioning (WebDAV) requests are not transmitted. In addition, any services that explicitly depend on the Web Client service will not start, and an error message will be logged in the System log. For example, WebDAV shares will be inaccessible from the client computer.

  How to undo the workaround.

  To re-enable the WebClient Service, follow these steps:

  1. Click Start, click Run, type Services.msc and then click OK.
  2. Right-click WebClient service and select Properties.
  3. Change the Startup type to Automatic. If the service is not running, click Start.
  4. Click OK and exit the management application.
• Block TCP ports 139 and 445 at the firewall

  These ports are used to initiate a connection with the affected component. Blocking TCP ports 139 and 445 at the firewall will help protect systems that are behind that firewall from attempts to exploit this vulnerability. Microsoft recommends that you block all unsolicited inbound communication from the Internet to help prevent attacks that may use other ports. For more information about ports, see the TechNet article, TCP and UDP Port Assignments.

  Impact of workaround. Several Windows services use the affected ports. Blocking connectivity to the ports may cause various applications or services to not function. Some of the applications or services that could be impacted are listed below:

  • Applications that use SMB (CIFS)
  • Applications that use mailslots or named pipes (RPC over SMB)
  • Server (File and Print Sharing)
  • Group Policy
  • Net Logon
  • Distributed File System (DFS)
  • Terminal Server Licensing
  • Print Spooler
  • Computer Browser
  • Remote Procedure Call Locator
  • Fax Service
  • Indexing Service
  • Performance Logs and Alerts
  • Systems Management Server
  • License Logging Service

  How to undo the workaround. Unblock TCP ports 139 and 445 at the firewall. For more information about ports, see TCP and UDP Port Assignments.

What is the scope of the vulnerability? 
This is a remote code execution vulnerability. 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.

What causes the vulnerability? 
This vulnerability requires a user to open a document contained within the same working directory as a specially crafted DLL file. The specially crafted DLL will be loaded into memory giving the attacker control of the affected system in the security context of the logged-on user.

Is this vulnerability related to the issue described in Microsoft Security Advisory 2269637? 
Yes, this vulnerability is related to the class of vulnerabilities that affect how applications load external libraries described in Microsoft Security Advisory 2269637. This security bulletin addresses a particular instance of this type of vulnerability.

What might an attacker use the vulnerability to do? 
An attacker who successfully exploited this vulnerability could run arbitrary code as the logged-on user. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. If a user is logged-on with administrative user rights, an attacker could take complete control of the affected system. 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.

How could an attacker exploit the vulnerability? 
This vulnerability requires that a user open an office document in the same working directory as a specially crafted DLL file.

In an e-mail attack scenario, an attacker could exploit the vulnerability by convincing a user to place an Office file in the same folder as a specially crafted DLL file, and then convincing the user to open the Office file. When the user opens the Office file the specially crafted DLL file, which is contained in the same directory as the Office file, will be loaded.

What systems are primarily at risk from the vulnerability? 
Systems where Microsoft Office is used, including workstations and terminal servers, are primarily at risk. Servers could be at more risk if administrators allow users to log on to servers and to run programs. However, best practices strongly discourage allowing this.

How is Microsoft Office affected by this vulnerability? 
Although the known attack vectors can only leverage Microsoft PowerPoint, the vulnerable code exists in a shared component of Microsoft Office.

What does the update do? 
This update addresses the vulnerability by helping to ensure the vulnerable component of Microsoft Office uses a more appropriate and secure search order when loading libraries.

When this security bulletin was issued, had this vulnerability been publicly disclosed? 
Yes. This vulnerability had been publicly disclosed when this security bulletin was originally issued.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited? 
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.

Reference Table

The following table contains the security update information for this software. You can find additional information in the subsection, Deployment Information, in this section.

Reference Table

The following table contains the security update information for this software. You can find additional information in the Deployment Information subsection below.

Reference Table

The following table contains the security update information for this software. You can find additional information in the subsection, Deployment Information, in this section.

Reference Table

The following table contains the security update information for this software. You can find additional information in the subsection, Deployment Information, in this section.