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HistoryMar 10, 2010 - 12:00 a.m.

Microsoft Security Bulletin MS10-017 - Important Vulnerabilities in Microsoft Office Excel Could Allow Remote Code Execution (980150)

2010-03-1000:00:00
vulners.com
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Microsoft Security Bulletin MS10-017 - Important
Vulnerabilities in Microsoft Office Excel Could Allow Remote Code Execution (980150)
Published: March 09, 2010

Version: 1.0
General Information
Executive Summary

This security update resolves seven privately reported vulnerabilities in Microsoft Office Excel. The vulnerabilities could allow remote code execution if a user opens a specially crafted Excel file. An attacker who successfully exploited any of these vulnerabilities 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.

This security update is rated Important for all supported editions of Microsoft Office Excel 2002, Microsoft Office Excel 2003, Microsoft Office Excel 2007, Microsoft Office 2004 for Mac, and Microsoft Office 2008 for Mac; Open XML File Format Converter for Mac; and all supported versions of Microsoft Office Excel Viewer and Microsoft Office Compatibility Pack. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The update addresses the vulnerabilities by changing the way that Microsoft Office Excel parses specially crafted Excel files. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability entry under the next section, Vulnerability Information.)

Recommendation. Microsoft recommends that customers apply the update at the earliest opportunity.

Known Issues. Microsoft Knowledge Base Article 980150 documents the currently known issues that customers may experience when installing this security update. The article also documents recommended solutions for these issues. When currently known issues and recommended solutions pertain only to specific releases of this software, this article provides links to further articles.
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Affected and Non-Affected Software

The following software have been tested to determine which versions or editions are affected. Other versions or editions are either past their support life cycle or are not affected. To determine the support life cycle for your software version or edition, visit Microsoft Support Lifecycle.

Affected Software
Office Suite and Other Software Component Maximum Security Impact Aggregate Severity Rating Bulletins Replaced by this Update
Microsoft Office Suites and Components

Microsoft Office XP Service Pack 3

Microsoft Office Excel 2002 Service Pack 3
(KB978471)

Remote Code Execution

Important

MS09-067

Microsoft Office 2003 Service Pack 3

Microsoft Office Excel 2003 Service Pack 3
(KB978474)

Remote Code Execution

Important

MS09-067

2007 Microsoft Office System Service Pack 1

Microsoft Office Excel 2007 Service Pack 1[1]
(KB978382)

Remote Code Execution

Important

MS09-067

2007 Microsoft Office System Service Pack 2

Microsoft Office Excel 2007 Service Pack 2[1]
(KB978382)

Remote Code Execution

Important

MS09-067
Microsoft Office for Mac

Microsoft Office 2004 for Mac
(KB980837)

Not applicable

Remote Code Execution

Important

None

Microsoft Office 2008 for Mac
(KB980839)

Not applicable

Remote Code Execution

Important

None

Open XML File Format Converter for Mac
(KB980840)

Not applicable

Remote Code Execution

Important

None
Other Office Software

Microsoft Office Excel Viewer Service Pack 1 and Microsoft Office Excel Viewer Service Pack 2
(KB978383)

Not applicable

Remote Code Execution

Important

MS09-067

Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats Service Pack 1 and Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats Service Pack 2
(KB978380)

Not applicable

Remote Code Execution

Important

MS09-067

Microsoft Office SharePoint Server 2007 Service Pack 1 (32-bit editions)[2]
(KB979439)

Not applicable

Remote Code Execution

Important

MS09-021

Microsoft Office SharePoint Server 2007 Service Pack 2 (32-bit editions)[2]
(KB979439)

Not applicable

Remote Code Execution

Important

MS09-021

Microsoft Office SharePoint Server 2007 Service Pack 1 (64-bit editions)[2]
(KB979439)

Not applicable

Remote Code Execution

Important

MS09-021

Microsoft Office SharePoint Server 2007 Service Pack 2 (64-bit editions)[2]
(KB979439)

Not applicable

Remote Code Execution

Important

MS09-021

[1]For Microsoft Office Excel 2007 Service Pack 1 and Microsoft Office Excel 2007 Service Pack 2, in addition to security update package KB978382, customers also need to install the security update for Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats Service Pack 1 and Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats Service Pack 2 (KB978380) to be protected from the vulnerabilities described in this bulletin.

[2]This update applies to servers that have Excel Services installed, such as the default configuration of Microsoft Office SharePoint Server 2007 Enterprise and Microsoft Office SharePoint Server 2007 for Internet sites. Microsoft Office SharePoint Server 2007 Standard does not include Excel Services.

Non-Affected Software
Office and Other Software

Microsoft Office File Converter Pack

Microsoft Works 8.5

Microsoft Works 9
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Frequently Asked Questions (FAQ) Related to This Security Update

Where are the file information details?
Refer to the reference tables in the Security Update Deployment section for the location of the file information details.

What are the known issues that customers may experience when installing this security update?
Microsoft Knowledge Base Article 980150 documents the currently known issues that customers may experience when they install this security update. The article also documents recommended solutions for these issues.

Why does this update address several reported security vulnerabilities?
This update contains support for several vulnerabilities because the modifications that are required to address these issues are located in related files. Instead of having to install several updates that are almost the same, customers need to install this update only.

What components of the Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats are updated by this bulletin?
The update included with this security bulletin applies only to the specific component within the Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats that is affected. For example, in an Excel bulletin, only the Excel compatibility pack component files are included in the update packages and not Word or PowerPoint compatibility pack component files. Word compatibility pack component files are updated in a Word bulletin and PowerPoint compatibility pack component files are updated in a PowerPoint bulletin.

What is the Microsoft Office Excel Viewer?
The Microsoft Office Excel Viewer is a replacement for all previous Excel Viewer versions, including Excel Viewer 97 and Excel Viewer 2003. With Excel Viewer, you can open, view, and print Excel workbooks, even if you don't have Excel installed. You can also copy data from Excel Viewer to another program. However, you cannot edit data, save a workbook, or create a new workbook.

Why is Microsoft Office SharePoint Server 2007 affected?
Excel Services in Microsoft Office SharePoint Server uses code that is based on the Excel client, which is affected by vulnerabilities as detailed in the Vulnerability Information section of this bulletin.

Note There are three components to Microsoft Office SharePoint Server 2007: Microsoft Office SharePoint Server core components, Excel Services, and InfoPath Forms Services. This update impacts the Excel Services component of Microsoft Office SharePoint Sever 2007.

I use Microsoft Office 2007 Service Pack 1. Are any additional security features included in this update?
Yes, as part of the servicing model for Microsoft Office 2007, when users of Microsoft Office 2007 Service Pack 1 install this update, their systems will be upgraded to security functionality that was initially released with Microsoft Office 2007 Service Pack 2. All updates released after April 24, 2009 for Microsoft Office 2007 will include these security features, which were introduced in Microsoft Office 2007 Service Pack 2. We have thoroughly tested this update, but as with all updates, we recommend that users perform testing appropriate to the environment and configuration of their systems.

The Office component discussed in this article is part of the Office Suite that I have installed on my system; however, I did not choose to install this specific component. Will I be offered this update?
Yes, if the version of the Office Suite installed on your system shipped with the component discussed in this bulletin, the system will be offered updates for it whether the component is installed or not. The detection logic used to scan for affected systems is designed to check for updates for all components that shipped with the particular Office Suite and offer the updates to a system. Users who choose not to apply an update for a component that is not installed, but is included in their version of the Office Suite, will not increase the security risk of that system. On the other hand, users who do choose to install the update will not have a negative impact on the security or performance of a system.

Does the offer to update a non-vulnerable version of Microsoft Office constitute an issue in the Microsoft update mechanism?
No, the update mechanism is functioning correctly in that it detects a lower version of the files on the system than in the update package and thus, offers the update.

Why is this update only Important for all affected versions of Excel?
Microsoft Office Excel 2002 and later versions have a built-in feature that prompts a user to Open, Save, or Cancel before opening a document. This mitigating factor reduces the vulnerability from Critical to Important because the vulnerability requires more than a single user action to complete the exploit.

I am using an older release of the software discussed in this security bulletin. What should I do?
The affected software listed in this bulletin have been tested to determine which releases are affected. Other releases are past their support life cycle. For more information about the product lifecycle, visit the Microsoft Support Lifecycle Web site.

It should be a priority for customers who have older releases of the software to migrate to supported releases to prevent potential exposure to vulnerabilities. To determine the support lifecycle for your software release, see Select a Product for Lifecycle Information. For more information about service packs for these software releases, see Lifecycle Supported Service Packs.

Customers who require custom support for older software must contact their Microsoft account team representative, their Technical Account Manager, or the appropriate Microsoft partner representative for custom support options. Customers without an Alliance, Premier, or Authorized Contract can contact their local Microsoft sales office. For contact information, visit the Microsoft Worldwide Information Web site, select the country in the Contact Information list, and then click Go to see a list of telephone numbers. When you call, ask to speak with the local Premier Support sales manager. For more information, see the Microsoft Support Lifecycle Policy FAQ.
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Vulnerability Information

Severity Ratings and Vulnerability Identifiers

The following severity ratings assume the potential maximum impact of the vulnerability. For information regarding the likelihood, within 30 days of this security bulletin's release, of the exploitability of the vulnerability in relation to its severity rating and security impact, please see the Exploitability Index in the March bulletin summary. For more information, see Microsoft Exploitability Index.
Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Affected Software Microsoft Office Excel Record Memory Corruption Vulnerability - CVE-2010-0257 Microsoft Office Excel Sheet Object Type Confusion Vulnerability - CVE-2010-0258 Microsoft Office Excel MDXTUPLE Record Heap Overflow Vulnerability - CVE-2010-0260 Microsoft Office Excel MDXSET Record Heap Overflow Vulnerability - CVE-2010-0261 Microsoft Office Excel FNGROUPNAME Record Uninitialized Memory Vulnerability - CVE-2010-0262 Microsoft Office Excel XLSX File Parsing Code Execution Vulnerability - CVE-2010-0263 Microsoft Office Excel DbOrParamQry Record Parsing Vulnerability - CVE-2010-0264 Aggregate Severity Rating
Microsoft Office Suites and Components

Microsoft Office Excel 2002 Service Pack 3

Important
Remote Code Execution

Important
Remote Code Execution

Not applicable

Not applicable

Not applicable

Not applicable

Important
Remote Code Execution

Important

Microsoft Office Excel 2003 Service Pack 3

Not applicable

Important
Remote Code Execution

Not applicable

Not applicable

Not applicable

Not applicable

Not applicable

Important

Microsoft Office Excel 2007 Service Pack 1 and Microsoft Office Excel 2007 Service Pack 2

Not applicable

Important
Remote Code Execution

Important
Remote Code Execution

Important
Remote Code Execution

Important
Remote Code Execution

Important
Remote Code Execution

Not applicable

Important
Microsoft Office for Mac

Microsoft Office 2004 for Mac

Not applicable

Important
Remote Code Execution

Not applicable

Not applicable

Important
Remote Code Execution

Not applicable

Important
Remote Code Execution

Important

Microsoft Office 2008 for Mac

Not applicable

Important
Remote Code Execution

Not applicable

Not applicable

Not applicable

Important
Remote Code Execution

Important
Remote Code Execution

Important

Open XML File Format Converter for Mac

Not applicable

Important
Remote Code Execution

Not applicable

Not applicable

Not applicable

Important
Remote Code Execution

Important
Remote Code Execution

Important
Other Office Software

Microsoft Office Excel Viewer Service Pack 1 and Microsoft Office Excel Viewer Service Pack 2

Not applicable

Important
Remote Code Execution

Important
Remote Code Execution

Not applicable

Not applicable

Important
Remote Code Execution

Not applicable

Important

Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats Service Pack 1 and Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats Service Pack 2

Not applicable

Important
Remote Code Execution

Important
Remote Code Execution

Important
Remote Code Execution

Not applicable

Important
Remote Code Execution

Not applicable

Important

Microsoft Office SharePoint Server 2007 Service Pack 1 (32-bit editions) and Microsoft Office SharePoint Server 2007 Service Pack 2 (32-bit editions)

Not applicable

Not applicable

Not applicable

Not applicable

Not applicable

Important
Remote Code Execution

Not applicable

Important

Microsoft Office SharePoint Server 2007 Service Pack 1 (64-bit editions) and Microsoft Office SharePoint Server 2007 Service Pack 2 (64-bit editions)

Not applicable

Not applicable

Not applicable

Not applicable

Not applicable

Important
Remote Code Execution

Not applicable

Important
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Microsoft Office Excel Record Memory Corruption Vulnerability - CVE-2010-0257

A remote code execution vulnerability exists in the way that Microsoft Office Excel handles specially crafted Excel files. 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.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-0257.

Mitigating Factors for Microsoft Office Excel Record Memory Corruption Vulnerability - CVE-2010-0257

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 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 Excel file.

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.
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Workarounds for Microsoft Office Excel Record Memory Corruption Vulnerability - CVE-2010-0257

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 Excel 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.
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FAQ for Microsoft Office Excel Record Memory Corruption Vulnerability - CVE-2010-0257

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 Office Excel parses the Excel file format when opening a specially crafted Excel 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?
Exploitation of this vulnerability requires that a user open a specially crafted Excel file with an affected version of Microsoft Office Excel.

In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a specially crafted Excel 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 an Excel 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 Excel file.

What systems are primarily at risk from the vulnerability?
Systems where Microsoft Office Excel 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 Office Excel parses specially crafted Excel files.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible 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.
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Microsoft Office Excel Sheet Object Type Confusion Vulnerability - CVE-2010-0258

A remote code execution vulnerability exists in the way that Microsoft Office Excel handles specially crafted Excel files. 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.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-0258.

Mitigating Factors for Microsoft Office Excel Sheet Object Type Confusion Vulnerability - CVE-2010-0258

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 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 Excel file.

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.
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Workarounds for Microsoft Office Excel Sheet Object Type Confusion Vulnerability - CVE-2010-0258

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\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 2007 Office system

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 the 2007 Microsoft Office system, all of the latest security updates for the 2007 Microsoft Office system must be applied.

Impact of workaround. 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 in Office 2003 or 2007 Microsoft Office System.

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 2007 Office system

Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Excel\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) will protect Office 2003 installations by more securely opening Word, Excel, and PowerPoint binary format files.

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

To install MOICE, you must 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:

Download the FileFormatConverters.exe package now

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

http://update.microsoft.com/microsoftupdate/v6/default.aspx?ln=en-us

For Excel

To enable MOICE, change the registered handler for the .xls, .xlt, and .xla file formats. The following table describes the command to enable or to disable MOICE for the .xls, .xlt, and .xla file formats:
Command to enable MOICE to be the registered handler Command to disable MOICE as the registered handler

ASSOC .XLS=oice.excel.sheet

ASSOC .xls=Excel.Sheet.8

ASSOC .XLT=oice.excel.template

ASSOC .xlt=Excel.Template

ASSOC .XLA=oice.excel.addin

ASSOC .xla=Excel.Addin

Note On Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2, the commands above will need to be run 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 2007 Microsoft Office System 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.

Do not open Excel 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.
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FAQ for Microsoft Office Excel Sheet Object Type Confusion Vulnerability - CVE-2010-0258

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 Office Excel parses the Excel file format when opening a specially crafted Excel 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?
Exploitation of this vulnerability requires that a user open a specially crafted Excel file with an affected version of Microsoft Office Excel.

In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a specially crafted Excel 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 an Excel 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 Excel file.

What systems are primarily at risk from the vulnerability?
Systems where Microsoft Office Excel 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 Office Excel parses specially crafted Excel files.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible 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.
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Microsoft Office Excel MDXTUPLE Record Heap Overflow Vulnerability - CVE-2010-0260

A remote code execution vulnerability exists in the way that Microsoft Office Excel handles specially crafted Excel files. 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.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-0260.

Mitigating Factors for Microsoft Office Excel MDXTUPLE Record Heap Overflow Vulnerability - CVE-2010-0260

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 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 Excel file.

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.
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Workarounds for Microsoft Office Excel MDXTUPLE Record Heap Overflow Vulnerability - CVE-2010-0260

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\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 2007 Office system

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 the 2007 Microsoft Office system, all of the latest security updates for the 2007 Microsoft Office system must be applied.

Impact of workaround. 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 in Office 2003 or 2007 Microsoft Office System.

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 2007 Office system

Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Excel\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) will protect Office 2003 installations by more securely opening Word, Excel, and PowerPoint binary format files.

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

To install MOICE, you must 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:

Download the FileFormatConverters.exe package now

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

http://update.microsoft.com/microsoftupdate/v6/default.aspx?ln=en-us

For Excel

To enable MOICE, change the registered handler for the .xls, .xlt, and .xla file formats. The following table describes the command to enable or to disable MOICE for the .xls, .xlt, and .xla file formats:
Command to enable MOICE to be the registered handler Command to disable MOICE as the registered handler

ASSOC .XLS=oice.excel.sheet

ASSOC .xls=Excel.Sheet.8

ASSOC .XLT=oice.excel.template

ASSOC .xlt=Excel.Template

ASSOC .XLA=oice.excel.addin

ASSOC .xla=Excel.Addin

Note On Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2, the commands above will need to be run 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 2007 Microsoft Office System 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.

Do not open Excel 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.
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FAQ for Microsoft Office Excel MDXTUPLE Record Heap Overflow Vulnerability - CVE-2010-0260

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 Office Excel parses the Excel file format when opening a specially crafted Excel 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?
Exploitation of this vulnerability requires that a user open a specially crafted Excel file with an affected version of Microsoft Office Excel.

In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a specially crafted Excel 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 an Excel 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 Excel file.

What systems are primarily at risk from the vulnerability?
Systems where Microsoft Office Excel 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 Office Excel parses specially crafted Excel files.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible 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.
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Microsoft Office Excel MDXSET Record Heap Overflow Vulnerability - CVE-2010-0261

A remote code execution vulnerability exists in the way that Microsoft Office Excel handles specially crafted Excel files. 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.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-0261.

Mitigating Factors for Microsoft Office Excel MDXSET Record Heap Overflow Vulnerability - CVE-2010-0261

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 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 Excel file.

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.
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Workarounds for Microsoft Office Excel MDXSET Record Heap Overflow Vulnerability - CVE-2010-0261

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\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 2007 Office system

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 the 2007 Microsoft Office system, all of the latest security updates for the 2007 Microsoft Office system must be applied.

Impact of workaround. 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 in Office 2003 or 2007 Microsoft Office System.

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 2007 Office system

Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Excel\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) will protect Office 2003 installations by more securely opening Word, Excel, and PowerPoint binary format files.

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

To install MOICE, you must 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:

Download the FileFormatConverters.exe package now

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

http://update.microsoft.com/microsoftupdate/v6/default.aspx?ln=en-us

For Excel

To enable MOICE, change the registered handler for the .xls, .xlt, and .xla file formats. The following table describes the command to enable or to disable MOICE for the .xls, .xlt, and .xla file formats:
Command to enable MOICE to be the registered handler Command to disable MOICE as the registered handler

ASSOC .XLS=oice.excel.sheet

ASSOC .xls=Excel.Sheet.8

ASSOC .XLT=oice.excel.template

ASSOC .xlt=Excel.Template

ASSOC .XLA=oice.excel.addin

ASSOC .xla=Excel.Addin

Note On Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2, the commands above will need to be run 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 2007 Microsoft Office System 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.

Do not open Excel 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.
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FAQ for Microsoft Office Excel MDXSET Record Heap Overflow Vulnerability - CVE-2010-0261

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 Office Excel parses the Excel file format when opening a specially crafted Excel 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?
Exploitation of this vulnerability requires that a user open a specially crafted Excel file with an affected version of Microsoft Office Excel.

In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a specially crafted Excel 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 an Excel 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 Excel file.

What systems are primarily at risk from the vulnerability?
Systems where Microsoft Office Excel 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 Office Excel parses specially crafted Excel files.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible 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.
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Microsoft Office Excel FNGROUPNAME Record Uninitialized Memory Vulnerability - CVE-2010-0262

A remote code execution vulnerability exists in the way that Microsoft Office Excel handles specially crafted Excel files. 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.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-0262.

Mitigating Factors for Microsoft Office Excel FNGROUPNAME Record Uninitialized Memory Vulnerability - CVE-2010-0262

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 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 Excel file.

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.
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Workarounds for Microsoft Office Excel FNGROUPNAME Record Uninitialized Memory Vulnerability - CVE-2010-0262

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 2007 Office system

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 the 2007 Microsoft Office system, all of the latest security updates for the 2007 Microsoft Office system must be applied.

Impact of workaround. 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 in Office 2003 or 2007 Microsoft Office System.

How to undo the workaround:

For 2007 Office system

Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Excel\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) will protect Office 2003 installations by more securely opening Word, Excel, and PowerPoint binary format files.

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

To install MOICE, you must 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:

Download the FileFormatConverters.exe package now

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

http://update.microsoft.com/microsoftupdate/v6/default.aspx?ln=en-us

For Excel

To enable MOICE, change the registered handler for the .xls, .xlt, and .xla file formats. The following table describes the command to enable or to disable MOICE for the .xls, .xlt, and .xla file formats:
Command to enable MOICE to be the registered handler Command to disable MOICE as the registered handler

ASSOC .XLS=oice.excel.sheet

ASSOC .xls=Excel.Sheet.8

ASSOC .XLT=oice.excel.template

ASSOC .xlt=Excel.Template

ASSOC .XLA=oice.excel.addin

ASSOC .xla=Excel.Addin

Note On Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2, the commands above will need to be run 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 2007 Microsoft Office System 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.

Do not open Excel 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.
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FAQ for Microsoft Office Excel FNGROUPNAME Record Uninitialized Memory Vulnerability - CVE-2010-0262

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 Office Excel parses the Excel file format when opening a specially crafted Excel 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?
Exploitation of this vulnerability requires that a user open a specially crafted Excel file with an affected version of Microsoft Office Excel.

In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a specially crafted Excel 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 an Excel 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 Excel file.

What systems are primarily at risk from the vulnerability?
Systems where Microsoft Office Excel 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 Office Excel parses specially crafted Excel files.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible 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.
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Microsoft Office Excel XLSX File Parsing Code Execution Vulnerability - CVE-2010-0263

A remote code execution vulnerability exists in the way that Microsoft Office Excel handles specially crafted Excel files. 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.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-0263.

Mitigating Factors for Microsoft Office Excel XLSX File Parsing Code Execution Vulnerability - CVE-2010-0263

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 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 Excel file.

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.
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Workarounds for Microsoft Office Excel XLSX File Parsing Code Execution Vulnerability - CVE-2010-0263

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 2007documents 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]
"OpenXMLFiles"=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 2007 Office system

Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Excel\Security\FileOpenBlock]
"OpenXMLFiles"=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.

Impact of workaround. 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 2007 files in Office 2003 or 2007 Microsoft Office System.

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]
"OpenXMLFiles"=dword:00000000

For 2007 Office system

Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Excel\Security\FileOpenBlock]
" OpenXMLFiles"=dword:00000000
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FAQ for Microsoft Office Excel XLSX File Parsing Code Execution Vulnerability - CVE-2010-0263

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 Office Excel parses the Excel file format when opening a specially crafted Excel 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?
Exploitation of this vulnerability requires that a user open a specially crafted Excel file with an affected version of Microsoft Office Excel.

In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a specially crafted Excel 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 an Excel 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 Excel file.

What systems are primarily at risk from the vulnerability?
Systems where Microsoft Office Excel 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 Office Excel parses specially crafted Excel files.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible 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.
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Microsoft Office Excel DbOrParamQry Record Parsing Vulnerability - CVE-2010-0264

A remote code execution vulnerability exists in the way that Microsoft Office Excel handles specially crafted Excel files. 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.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2010-0264.

Mitigating Factors for Microsoft Office Excel DbOrParamQry Record Parsing Vulnerability - CVE-2010-0264

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 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 Excel file.

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.
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Workarounds for Microsoft Office Excel DbOrParamQry Record Parsing Vulnerability - CVE-2010-0264

Microsoft has not identified any workarounds for this vulnerability.
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FAQ for Microsoft Office Excel DbOrParamQry Record Parsing Vulnerability - CVE-2010-0264

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 Office Excel parses the Excel file format when opening a specially crafted Excel 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?
Exploitation of this vulnerability requires that a user open a specially crafted Excel file with an affected version of Microsoft Office Excel.

In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a specially crafted Excel 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 an Excel 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 Excel file.

What systems are primarily at risk from the vulnerability?
Systems where Microsoft Office Excel 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 Office Excel parses specially crafted Excel files.

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

Other Information
Acknowledgments

Microsoft thanks the following for working with us to help protect customers:

Nicolas Joly of VUPEN Vulnerability Research Team for reporting the Microsoft Office Excel Record Memory Corruption Vulnerability (CVE-2010-0257)

Sean Larsson of VeriSign iDefense Labs for reporting the Microsoft Office Excel Sheet Object Type Confusion Vulnerability (CVE-2010-0258)

Sean Larsson of VeriSign iDefense Labs for reporting the Microsoft Office Excel MDXTUPLE Record Heap Overflow Vulnerability (CVE-2010-0260)

Sean Larsson of VeriSign iDefense Labs for reporting the Microsoft Office Excel MDXSET Record Heap Overflow Vulnerability (CVE-2010-0261)

Sean Larsson of VeriSign iDefense Labs for reporting the Microsoft Office Excel FNGROUPNAME Record Uninitialized Memory Vulnerability (CVE-2010-0262)

An anonymous researcher, working with TippingPoint's Zero Day Initiative, for reporting the Microsoft Office Excel XLSX File Parsing Code Execution Vulnerability (CVE-2010-0263)

Damián Frizza of Core Security Technologies for reporting the Microsoft Office Excel DbOrParamQry Record Parsing Vulnerability (CVE-2010-0264)
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Microsoft Active Protections Program (MAPP)

To improve security protections for customers, Microsoft provides vulnerability information to major security software providers in advance of each monthly security update release. Security software providers can then use this vulnerability information to provide updated protections to customers via their security software or devices, such as antivirus, network-based intrusion detection systems, or host-based intrusion prevention systems. To determine whether active protections are available from security software providers, please visit the active protections Web sites provided by program partners, listed in Microsoft Active Protections Program (MAPP) Partners.

Support

Customers in the U.S. and Canada can receive technical support from Security Support or 1-866-PCSAFETY. There is no charge for support calls that are associated with security updates. For more information about available support options, see Microsoft Help and Support.

International customers can receive support from their local Microsoft subsidiaries. There is no charge for support that is associated with security updates. For more information about how to contact Microsoft for support issues, visit the International Support Web site.

Disclaimer

The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.

Revisions

V1.0 (March 9, 2010): Bulletin published.