SecurityvulnsSECURITYVULNS:DOC:19380Microsoft Security Bulletin MS08-014 - Critical Vulnerabilities in Microsoft Excel Could Allow Remote Code Execution (949029)
Microsoft Security Bulletin MS08-014 - Critical
Vulnerabilities in Microsoft Excel Could Allow Remote Code Execution (949029)
Published: March 11, 2008
Version: 1.0
General Information
Executive Summary
This security update resolves several privately reported and publicly reported vulnerabilities in Microsoft Office Excel that could allow remote code execution if a user opens a specially crafted Excel file. An attacker who successfully exploited these vulnerabilities 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.
This security update is rated Critical for Microsoft Office Excel 2000 Service Pack 3 and rated Important for Excel 2002 Service Pack 3, Excel 2003 Service Pack 2, Excel Viewer 2003, Excel 2007, Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats, Office 2004 for Mac, and Office 2008 for Mac. For more information, see the subsection, Affected and Non-Affected Software, in this section.
This security update addresses these vulnerabilities by modifying the way that Microsoft Excel performs validations when opening 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.
This security update also addresses the vulnerability first described in Microsoft Security Advisory 947563.
Recommendation. Microsoft recommends that customers apply the update immediately
Known Issues. None
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Affected and Non-Affected Software
The software listed here 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 2000 Service Pack 3
Excel 2000 Service Pack 3
(KB946979)
Remote Code Execution
Critical
MS07-044
Microsoft Office XP Service Pack 3
Excel 2002 Service Pack 3
(KB946976)
Remote Code Execution
Important
MS07-044
Microsoft Office 2003 Service Pack 2
Excel 2003 Service Pack 2
(KB943985)
Remote Code Execution
Important
MS07-044
2007 Microsoft Office System
Excel 2007
(KB946974)
Remote Code Execution
Important
MS07-036
Microsoft Office Excel Viewer 2003
(KB943889)
Remote Code Execution
Important
MS07-044
Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats
(KB947801)
Remote Code Execution
Important
MS07-036
Microsoft Office 2004 for Mac
(KB949357)
Remote Code Execution
Important
MS08-013
Microsoft Office 2008 for Mac
(KB948057)
Remote Code Execution
Important
None
Non-Affected Software
Office Suite and Other Software Component
Microsoft Office 2003 Service Pack 3
Excel 2003 Service Pack 3
2007 Microsoft Office System Service Pack 1
Excel 2007 Service Pack 1
Microsoft Works 8.0
Microsoft Works 8.5
Microsoft Works 9.0
Microsoft Works Suite 2005
Microsoft Works Suite 2006
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Frequently Asked Questions (FAQ) Related to This Security Update
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. To determine the support life cycle for your software release, visit Microsoft Support Lifecycle.
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. For more information about the Windows Product Lifecycle, visit the following Microsoft Support Lifecycle. For more information about the extended security update support period for these software releases, visit the Microsoft Product Support Services Web site.
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, 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 Windows Operating System Product Support Lifecycle FAQ.
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Vulnerability Information
Severity Ratings and Vulnerability Identifiers
Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Affected Software Excel Data Validation Record Vulnerability – CVE-2008-0111 Excel File Import Vulnerability – CVE-2008-0112 Excel Style Record Vulnerability – CVE-2008-0114 Excel Formula Parsing Vulnerability – CVE-2008-0115 Excel Rich Text Validation Vulnerability – CVE-2008-0116 Excel Conditional Formatting Vulnerability – CVE-2008-0117 Macro Validation Vulnerability – CVE-2008-0081 Aggregate Severity Rating
Microsoft Office Excel 2000 Service Pack 3
Critical
Remote Code Execution
Critical
Remote Code Execution
Critical
Remote Code Execution
Critical
Remote Code Execution
Critical
Remote Code Execution
Critical
Remote Code Execution
Critical
Remote Code Execution
Critical
Microsoft Office Excel 2002 Service Pack 3
Important
Remote Code Execution
None
Important
Remote Code Execution
Important
Remote Code Execution
Important
Remote Code Execution
Important
Remote Code Execution
Important
Remote Code Execution
Important
Microsoft Office Excel 2003 Service Pack 2
Important
Remote Code Execution
None
Important
Remote Code Execution
Important
Remote Code Execution
Important
Remote Code Execution
None
Important
Remote Code Execution
Important
Microsoft Office Excel 2007
Important
Remote Code Execution
None
None
Important
Remote Code Execution
None
None
None
Important
Microsoft Office Excel Viewer 2003
Important
Remote Code Execution
None
Important
Remote Code Execution
Important
Remote Code Execution
Important
Remote Code Execution
None
Important
Remote Code Execution
Important
Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats
Important
Remote Code Execution
None
None
Important
Remote Code Execution
Important
Remote Code Execution
None
None
Important
Microsoft Office 2004 for Mac
Important
Remote Code Execution
Important
Remote Code Execution
Important
Remote Code Execution
Important
Remote Code Execution
Important
Remote Code Execution
Important
Remote Code Execution
Important
Remote Code Execution
Important
Microsoft Office 2008 for Mac
Important
Remote Code Execution
Important
Remote Code Execution
Important
Remote Code Execution
Important
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Excel Data Validation Record Vulnerability – CVE-2008-0111
A remote code execution vulnerability exists in the way Excel processes data validation records when loading Excel files into memory. An attacker could exploit the vulnerability by sending a malformed file which could be hosted on a specially crafted or compromised Web site, or included as an e-mail attachment.
To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2008-0111.
Mitigating Factors for Excel Data Validation Record Vulnerability – CVE-2008-0111
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:
•
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.
•
An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
•
The vulnerability 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.
•
Users who have installed and are using the Office Document Open Confirmation Tool for Office 2000 will be prompted with Open, Save, or Cancel before opening a document. The features of the Office Document Open Confirmation Tool are incorporated in Office XP and later editions of Office.
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Workarounds for Excel Data Validation Record Vulnerability – CVE-2008-0111
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 Office 2003, all of the latest Office 2003 security updates 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:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Excel\Security\FileOpenBlock]
"BinaryFiles"=dword:00000000
•
Do not open or save Microsoft 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.
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Excel Data Validation Record Vulnerability – CVE-2008-0111
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?
Microsoft Excel does not perform sufficient validation of data when loading Excel files into memory.
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?
This vulnerability requires that a user open a malformed Excel file with an affected version of Microsoft Excel.
In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a malformed 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 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 users to visit the Web site, typically by getting them to click a link that takes them to the attacker's site.
What systems are primarily at risk from the vulnerability?
Systems where Microsoft Excel is used 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 removes the vulnerability by modifying the way that Microsoft Excel handles data validation records when loading Excel files from disk to memory.
When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible disclosure. Microsoft had not received any information to indicate that this vulnerability had been publicly disclosed when this security bulletin was originally issued. This security bulletin addresses the privately disclosed vulnerability as well as additional issues discovered through internal investigations.
When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers and had not seen any examples of proof of concept code published when this security bulletin was originally issued.
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Excel File Import Vulnerability – CVE-2008-0112
A remote code execution vulnerability exists in the way Excel handles data when importing files into Excel. An attacker could exploit the vulnerability by sending a malformed .slk file which could be hosted on a specially crafted or compromised Web site, or included as an e-mail attachment, and which could then be imported into Excel.
To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2008-0112.
Mitigating Factors for Excel File Import Vulnerability – CVE-2008-0112
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:
•
In a Web-based attack scenario, an attacker would need to convince a user to import a malformed Excel file that could be hosted on a Web site 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.
•
An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
•
The vulnerability 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.
•
Users who have installed and are using the Office Document Open Confirmation Tool for Office 2000 will be prompted with Open, Save, or Cancel before opening a document. The features of the Office Document Open Confirmation Tool are incorporated in Office XP and later editions of Office.
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Workarounds for Excel File Import Vulnerability – CVE-2008-0112
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 or save Microsoft 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.
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FAQ for Excel File Import Vulnerability – CVE-2008-0112
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?
Microsoft Excel does not perform sufficient validation of file data when importing a file into Excel.
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?
This vulnerability requires that a user import a malformed Excel file with an affected version of Microsoft Excel.
In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a malformed Excel file to the user and by convincing the user to import the file in Excel.
In a Web-based attack scenario, an attacker would have to host a Web site that contains an Office file that is used to attempt to exploit this vulnerability. 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 users to visit the Web site, typically by getting them to click a link that takes them to the attacker's site.
What systems are primarily at risk from the vulnerability?
Systems where Microsoft Excel is used 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 removes the vulnerability by modifying the way that Microsoft Excel validates file data when importing .slk files into Excel. However, after applying this update, attempts to import a malformed .slk file may still cause Excel to exit unexpectedly. This behavior is not exploitable.
When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible disclosure. Microsoft had not received any information to indicate that this vulnerability had been publicly disclosed when this security bulletin was originally issued. This security bulletin addresses the privately disclosed vulnerability as well as additional issues discovered through internal investigations.
When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers and had not seen any examples of proof of concept code published when this security bulletin was originally issued.
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Excel Style Record Vulnerability – CVE-2008-0114
A remote code execution vulnerability exists in the way Excel handles Style record data when opening Excel files. An attacker could exploit the vulnerability by sending a malformed file which could be hosted on a specially crafted or compromised Web site, or included as an e-mail attachment.
To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2008-0114.
Mitigating Factors for Excel Style Record Vulnerability – CVE-2008-0114
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:
•
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.
•
An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
•
The vulnerability 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.
•
Users who have installed and are using the Office Document Open Confirmation Tool for Office 2000 will be prompted with Open, Save, or Cancel before opening a document. The features of the Office Document Open Confirmation Tool are incorporated in Office XP and later editions of Office.
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Workarounds for Style Record Vulnerability – CVE-2008-0114
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 the Microsoft Office Isolated Conversion Environment (MOICE) when opening files from unknown or un-trusted 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 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
To enable MOICE, change the registered handle 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 use to enable MOICE to be the registered handler Command to use 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
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.
•
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 Office 2003, all of the latest Office 2003 security updates 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:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Excel\Security\FileOpenBlock]
"BinaryFiles"=dword:00000000
•
Do not open or save Microsoft 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.
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FAQ for Excel Style Record Vulnerability – CVE-2008-0114
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 is caused by a memory handling error in Excel when validating Style record information upon opening a specially crafted Excel file. The error may corrupt system memory in such a way that an attacker could execute arbitrary code.
What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could 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?
This vulnerability requires that a user open a malformed Excel file with an affected version of Microsoft Excel.
In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a malformed 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 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.
What systems are primarily at risk from the vulnerability?
Systems where Microsoft Excel is used 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 removes the vulnerability by modifying the way that Microsoft Excel validates Style record information.
When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible disclosure. Microsoft had not received any information to indicate that this vulnerability had been publicly disclosed when this security bulletin was originally issued. This security bulletin addresses the privately disclosed vulnerability as well as additional issues discovered through internal investigations.
When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers and had not seen any examples of proof of concept code published when this security bulletin was originally issued.
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Excel Formula Parsing Vulnerability – CVE-2008-0115
A remote code execution vulnerability exists in the way Excel handles malformed formulas. An attacker could exploit the vulnerability by sending a malformed file which could be hosted on a specially crafted or compromised Web site, or included as an e-mail attachment.
To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2008-0115.
Mitigating Factors for Excel Formula Parsing Vulnerability – CVE-2008-0115
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:
•
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.
•
An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
•
The vulnerability 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.
•
Users who have installed and are using the Office Document Open Confirmation Tool for Office 2000 will be prompted with Open, Save, or Cancel before opening a document. The features of the Office Document Open Confirmation Tool are incorporated in Office XP and later editions of Office.
Top of sectionTop of section
Workarounds for Excel Formula Parsing Vulnerability – CVE-2008-0115
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 Office 2003, all of the latest Office 2003 security updates 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:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Excel\Security\FileOpenBlock]
"BinaryFiles"=dword:00000000
•
Do not open or save Microsoft 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.
Top of sectionTop of section
FAQ for Excel Formula Parsing Vulnerability – CVE-2008-0115
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 is caused by a memory calculation error when parsing formula information in a specially crafted Excel file. The error may corrupt system memory in such a way that an attacker could execute arbitrary code.
What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could 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?
This vulnerability requires that a user open a malformed Excel file with an affected version of Microsoft Excel.
In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a malformed 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 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.
What systems are primarily at risk from the vulnerability?
Systems where Microsoft Excel is used 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 removes the vulnerability by modifying the way that Microsoft Excel validates formula information when loading Excel files into memory.
When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible disclosure. Microsoft had not received any information to indicate that this vulnerability had been publicly disclosed when this security bulletin was originally issued. This security bulletin addresses the privately disclosed vulnerability as well as additional issues discovered through internal investigations.
When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers and had not seen any examples of proof of concept code published when this security bulletin was originally issued.
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Excel Rich Text Validation Vulnerability – CVE-2008-0116
A remote code execution vulnerability exists in the way Excel handles rich text values when loading application data into memory. An attacker could exploit the vulnerability by sending a malformed file which could be hosted on a specially crafted or compromised Web site, or included as an e-mail attachment.
To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2008-0116.
Mitigating Factors for Excel Rich Text Validation Vulnerability – CVE-2008-0116
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:
•
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.
•
An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
•
The vulnerability 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.
•
Users who have installed and are using the Office Document Open Confirmation Tool for Office 2000 will be prompted with Open, Save, or Cancel before opening a document. The features of the Office Document Open Confirmation Tool are incorporated in Office XP and later editions of Office.
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Workarounds for Excel Rich Text Validation Vulnerability – CVE-2008-0116
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 Office 2003, all of the latest Office 2003 security updates 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:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Excel\Security\FileOpenBlock]
"BinaryFiles"=dword:00000000
•
Do not open or save Microsoft 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.
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FAQ for Excel Rich Text Validation Vulnerability – CVE-2008-0116
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?
Microsoft Excel does not perform sufficient validation of rich text values when loading application data into memory.
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?
This vulnerability requires that a user open a malformed Excel file with an affected version of Microsoft Excel.
In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a malformed 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 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.
What systems are primarily at risk from the vulnerability?
Systems where Microsoft Excel is used 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 removes the vulnerability by modifying the way that Microsoft Excel validates rich text data values when loading 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. Microsoft had not received any information to indicate that this vulnerability had been publicly disclosed when this security bulletin was originally issued. This security bulletin addresses the privately disclosed vulnerability as well as additional issues discovered through internal investigations.
When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers and had not seen any examples of proof of concept code published when this security bulletin was originally issued.
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Excel Conditional Formatting Vulnerability – CVE-2008-0117
A remote code execution vulnerability exists in the way Excel handles conditional formatting values. An attacker could exploit the vulnerability by sending a malformed file which could be hosted on a specially crafted or compromised Web site, or included as an e-mail attachment.
To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2008-0117.
Mitigating Factors for Excel Conditional Formatting Vulnerability – CVE-2008-0117
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:
•
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.
•
An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
•
The vulnerability 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.
•
Users who have installed and are using the Office Document Open Confirmation Tool for Office 2000 will be prompted with Open, Save, or Cancel before opening a document. The features of the Office Document Open Confirmation Tool are incorporated in Office XP and later editions of Office.
Top of sectionTop of section
Workarounds for Excel Conditional Formatting Vulnerability – CVE-2008-0117
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 or save Microsoft 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.
Top of sectionTop of section
FAQ for Excel Conditional Formatting Vulnerability – CVE-2008-0117
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?
Microsoft Excel does not perform sufficient validation of conditional formatting values.
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?
This vulnerability requires that a user open a malformed Excel file with an affected version of Microsoft Excel.
In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a malformed 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 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.
What systems are primarily at risk from the vulnerability?
Systems where Microsoft Excel is used 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 removes the vulnerability by modifying the way that Microsoft Excel validates conditional formatting values when opening Excel files.
When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible disclosure. Microsoft had not received any information to indicate that this vulnerability had been publicly disclosed when this security bulletin was originally issued. This security bulletin addresses the privately disclosed vulnerability as well as additional issues discovered through internal investigations.
When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers and had not seen any examples of proof of concept code published when this security bulletin was originally issued.
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Macro Validation Vulnerability – CVE-2008-0081
A remote code execution vulnerability exists in the way Excel handles macros when opening specially crafted Excel files. An attacker could exploit the vulnerability by sending a malformed file which could be hosted on a specially crafted or compromised Web site, or included as an e-mail attachment.
To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2008-0081.
Mitigating Factors for Macro Validation Vulnerability – CVE-2008-0081
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:
•
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.
•
An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
•
The vulnerability 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.
•
Users who have installed and are using the Office Document Open Confirmation Tool for Office 2000 will be prompted with Open, Save, or Cancel before opening a document. The features of the Office Document Open Confirmation Tool are incorporated in Office XP and later editions of Office.
Top of sectionTop of section
Workarounds for Macro Validation Vulnerability – CVE-2008-0081
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 the Microsoft Office Isolated Conversion Environment (MOICE) when opening files from unknown or un-trusted 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 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
To enable MOICE, change the registered handle 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 use to enable MOICE to be the registered handler Command to use 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
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.
•
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.
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 Office 2003, all of the latest Office 2003 security updates 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:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Excel\Security\FileOpenBlock]
"BinaryFiles"=dword:00000000
•
Do not open or save Microsoft 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.
Top of sectionTop of section
FAQ for Macro Validation Vulnerability – CVE-2008-0081
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?
Microsoft Excel does not properly validate macro information when loading specially crafted Excel files.
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?
This vulnerability requires that a user open a malformed Excel file with an affected version of Microsoft 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 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.
What systems are primarily at risk from the vulnerability?
Systems where Microsoft Excel is used 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 removes the vulnerability by modifying the way that Microsoft Excel validates macro information.
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. It has been assigned the Common Vulnerability and Exposure number CVE-2008-0081. This vulnerability was first described in Microsoft Security Advisory 947563.
When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
Yes. When this security bulletin was issued, Microsoft had received information that this vulnerability was being exploited.
Additional Information
If you have technical questions or problems downloading or using this update, visit Microsoft for Mac Support to learn about the support options that are available to you.
Other Information
Acknowledgments
Microsoft thanks the following for working with us to help protect customers:
•
Mike Scott of SAIC for reporting the Macro Validation Vulnerability (CVE-2008-0081)
•
Matt Richard of VeriSign for reporting the Macro Validation Vulnerability (CVE-2008-0081)
•
Greg MacManus of iDefense Labs for reporting the Excel Data Validation Record Vulnerability (CVE-2008-0111)
•
Yoshiya Sasaki of JFE Systems for reporting the Excel File Import Vulnerability (CVE-2008-0112)
•
Bing Liu of Fortinet for reporting the Excel Style Record Vulnerability (CVE-2008-0114)
•
iDefense Labs for reporting the Excel Formula Parsing Vulnerability (CVE-2008-0115)
•
Cody Pierce of TippingPoint DVLabs for reporting the Excel Rich Text Validation Vulnerability (CVE-2008-0116)
•
Moti Joseph and Dan Hubbard of Websense Security Labs for reporting the Excel Conditional Formatting Vulnerability (CVE-2008-0117)
Support
•
Customers in the U.S. and Canada can receive technical support from Microsoft Product Support Services at 1-866-PCSAFETY. There is no charge for support calls that are associated with security updates.
•
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.
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Revisions
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V1.0 (March 11, 2008): Bulletin published.
Related
