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Security Bulletin

Microsoft Security Bulletin MS12-046 - Important

Vulnerability in Visual Basic for Applications Could Allow Remote Code Execution (2707960)

Published: July 10, 2012 | Updated: November 13, 2012

Version: 2.0

General Information

Executive Summary

This security update resolves one publicly disclosed vulnerability in Microsoft Visual Basic for Applications. The vulnerability could allow remote code execution if a user opens a legitimate Microsoft Office file (such as a .docx file) that is located in the same directory as a specially crafted dynamic link library (DLL) file. An attacker could then install programs; view, change, or delete data; or create new accounts that have full user rights. If a user is logged on with administrative user rights, an attacker could take complete control of the affected system. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.

This security update is rated Important for all supported versions of Microsoft Visual Basic for Applications SDK and third-party applications that use Microsoft Visual Basic for Applications. This security update is also rated Important for all supported editions of Microsoft Office 2003 SP3, Microsoft Office 2007 SP2, and Microsoft Office 2010. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerability by correcting how Microsoft Visual Basic for Applications loads external libraries. 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. Customers can configure automatic updating to check online for updates from Microsoft Update by using the Microsoft Update service. Customers who have automatic updating enabled and configured to check online for updates from Microsoft Update typically will not need to take any action because this security update will be downloaded and installed automatically. Customers who have not enabled automatic updating need to check for updates from Microsoft Update and install this update manually. For information about specific configuration options in automatic updating in supported editions of Windows XP and Windows Server 2003, see Microsoft Knowledge Base Article 294871. For information about automatic updating in supported editions of Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2, see Understanding Windows automatic updating.

For administrators and enterprise installations, or end users who want to install this security update manually, Microsoft recommends that customers apply the update at the earliest opportunity using update management software, or by checking for updates using the Microsoft Update service.

See also the section, Detection and Deployment Tools and Guidance, later in this bulletin.

Known Issues. Microsoft Knowledge Base Article 2707960 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.

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

Microsoft Office Suites and Software

^[2]The supported versions of the VBA SDK are Microsoft Visual Basic for Applications SDK 6.3, Microsoft Visual Basic for Applications SDK 6.4, and Microsoft Visual Basic for Applications SDK 6.5.

Visual Basic for Applications Insecure Library Loading Vulnerability - CVE-2012-1854

A remote code execution vulnerability exists in the way that Microsoft Visual Basic for Applications handles the loading of DLL 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. 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.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2012-1854.

Mitigating Factors for Visual Basic for Applications Insecure Library Loading Vulnerability - CVE-2012-1854

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

• The file sharing protocol, Server Message Block (SMB), is often disabled on the perimeter firewall. This limits the potential attack vectors for this vulnerability.
• For an attack to be successful, a user must visit an untrusted remote file system location or WebDAV share and open a legitimate Office-related file (such as a .docx file).
• 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.

Workarounds for Visual Basic for Applications Insecure Library Loading Vulnerability - CVE-2012-1854

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

• Disable loading of libraries from WebDAV and remote network shares

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

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

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

• Disable the WebClient service

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

  To disable the WebClient Service, follow these steps:

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

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

  How to undo the workaround.

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

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

• Block TCP ports 139 and 445 at the firewall

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

  Impact of workaround. Several Windows services use the affected ports. Blocking connectivity to the ports may cause various applications or services to not function. The following is a list of some of the applications or services that could be impacted:

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

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

FAQ for Visual Basic for Applications Insecure Library Loading Vulnerability - CVE-2012-1854

What is the scope of the vulnerability?
This is a remote code execution vulnerability in Microsoft Visual Basic for Applications (VBA).

What causes the vulnerability?
The vulnerability is caused when Microsoft Visual Basic for Applications incorrectly restricts the path used for loading external libraries.

What is Visual Basic for Applications (VBA)?
Microsoft VBA is a development technology for developing client desktop packaged applications and integrating them with existing data and systems. Microsoft VBA is based on the Microsoft Visual Basic development system. Microsoft Office products include VBA and use VBA to perform certain functions. VBA can also be used to build customized applications based around an existing host application.

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

How could an attacker exploit the vulnerability?
An attacker could convince a user to open a legitimate Microsoft Office-related file (such as a .docx file) that is located in the same network directory as a specially crafted dynamic link library (DLL) file. Then, while opening the legitimate file, Microsoft Office could attempt to load the DLL file and execute any code it contained.

In an email attack scenario, an attacker could exploit the vulnerability by sending a legitimate Microsoft Office-related file (such as a .docx file) to a user, and convincing the user to put the attachment into a directory that contains a specially crafted DLL file and to open the legitimate file. Then, while opening the legitimate file, Microsoft Office could attempt to load the DLL file and execute any code it contained.

In a network attack scenario, an attacker could put a legitimate Microsoft Office-related file and a specially crafted DLL file in a network share, a UNC, or WebDAV location and then convince the user to open the file.

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

What does the update do?
The update addresses this vulnerability by correcting how Microsoft Visual Basic for Applications loads external libraries.

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

When this security bulletin was issued, had this vulnerability been publicly disclosed?
Yes. This vulnerability has been publicly disclosed. It has been assigned Common Vulnerability and Exposure number CVE-2012-1854.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
Yes. Microsoft is aware of limited, targeted attacks attempting to exploit the vulnerability.

Update Information

Detection and Deployment Tools and Guidance

Security Central

Manage the software and security updates you need to deploy to the servers, desktop, and mobile systems in your organization. For more information see the TechNet Update Management Center. The Microsoft TechNet Security website provides additional information about security in Microsoft products.

Security updates are available from Microsoft Update and Windows Update. Security updates are also available from the Microsoft Download Center. You can find them most easily by doing a keyword search for "security update."

For customers of Microsoft Office for Mac, Microsoft AutoUpdate for Mac can help keep your Microsoft software up to date. For more information about using Microsoft AutoUpdate for Mac, see Check for software updates automatically.

Finally, security updates can be downloaded from the Microsoft Update Catalog. The Microsoft Update Catalog provides a searchable catalog of content made available through Windows Update and Microsoft Update, including security updates, drivers and service packs. By searching using the security bulletin number (such as, "MS07-036"), you can add all of the applicable updates to your basket (including different languages for an update), and download to the folder of your choosing. For more information about the Microsoft Update Catalog, see the Microsoft Update Catalog FAQ.

Detection and Deployment Guidance

Microsoft provides detection and deployment guidance for security updates. This guidance contains recommendations and information that can help IT professionals understand how to use various tools for detection and deployment of security updates. For more information, see Microsoft Knowledge Base Article 961747.

Microsoft Baseline Security Analyzer

Microsoft Baseline Security Analyzer (MBSA) allows administrators to scan local and remote systems for missing security updates as well as common security misconfigurations. For more information about MBSA, visit Microsoft Baseline Security Analyzer.

The following table provides the MBSA detection summary for this security update.

Note For customers using legacy software not supported by the latest release of MBSA, Microsoft Update, and Windows Server Update Services, please visit Microsoft Baseline Security Analyzer and reference the Legacy Product Support section on how to create comprehensive security update detection with legacy tools.

Windows Server Update Services

Windows Server Update Services (WSUS) enables information technology administrators to deploy the latest Microsoft product updates to computers that are running the Windows operating system. For more information about how to deploy security updates using Windows Server Update Services, see the TechNet article, Windows Server Update Services.

Systems Management Server

The following table provides the SMS detection and deployment summary for this security update.

Note Microsoft discontinued support for SMS 2.0 on April 12, 2011. For SMS 2003, Microsoft also discontinued support for the Security Update Inventory Tool (SUIT) on April 12, 2011. Customers are encouraged to upgrade to System Center Configuration Manager. For customers remaining on SMS 2003 Service Pack 3, the Inventory Tool for Microsoft Updates (ITMU) is also an option.

For SMS 2003, the SMS 2003 Inventory Tool for Microsoft Updates (ITMU) can be used by SMS to detect security updates that are offered by Microsoft Update and that are supported by Windows Server Update Services. For more information about the SMS 2003 ITMU, see SMS 2003 Inventory Tool for Microsoft Updates. For more information about SMS scanning tools, see SMS 2003 Software Update Scanning Tools. See also Downloads for Systems Management Server 2003.

System Center Configuration Manager uses WSUS 3.0 for detection of updates. For more information about System Center Configuration Manager Software Update Management, visit System Center.

For more information about SMS, visit the SMS website.

For more detailed information, see Microsoft Knowledge Base Article 910723: Summary list of monthly detection and deployment guidance articles.

Note If you have used an Administrative Installation Point (AIP) for deploying Office XP or Office 2003, you may not be able to deploy the update using SMS if you have updated the AIP from the original baseline. For more information, see the Office Administrative Installation Point heading in this section.

Office Administrative Installation Point

If you installed your application from a server location, the server administrator must update the server location with the administrative update and deploy that update to your system.

• For supported versions of Microsoft Office XP, see Creating an Administrative Installation Point. For more information on how to change the source for a client system from an updated administrative installation point to an Office XP original baseline source, see Microsoft Knowledge Base Article 922665.
  Note If you plan to manage software updates centrally from an updated administrative image, you can find more information in the article Updating Office XP Clients from a Patched Administrative Image.
• For supported versions of Microsoft Office 2003, see Creating an Administrative Installation Point. For more information on how to change the source for a client computer from an updated administrative installation point to an Office 2003 original baseline source or Service Pack 3 (SP3), see Microsoft Knowledge Base Article 902349.
  Note If you plan to manage software updates centrally from an updated administrative image, you can find more information in the article, Distributing Office 2003 Product Updates.
• For creating a network installation point for supported versions of Microsoft Office, see Create a network installation point for Microsoft Office.
  Note If you plan to manage security updates centrally, use Windows Server Update Services. For more information about how to deploy security updates for Microsoft Office, visit the Windows Server Update Services website.

Update Compatibility Evaluator and Application Compatibility Toolkit

Updates often write to the same files and registry settings required for your applications to run. This can trigger incompatibilities and increase the time it takes to deploy security updates. You can streamline testing and validating Windows updates against installed applications with the Update Compatibility Evaluator components included with Application Compatibility Toolkit.

The Application Compatibility Toolkit (ACT) contains the necessary tools and documentation to evaluate and mitigate application compatibility issues before deploying Windows Vista, a Windows Update, a Microsoft Security Update, or a new version of Windows Internet Explorer in your environment.

Security Update Deployment

Affected Software

For information about the specific security update for your affected software, click the appropriate link:

Office 2003 (all editions)

Reference Table

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

Supported Security Update Installation Switches

Note You can combine these switches into one command. For backward compatibility, the security update also supports many of the setup switches that the earlier version of the Setup program uses. For more information about the supported installation switches, see Microsoft Knowledge Base Article 262841.

Removing the Update

To remove this security update, use the Add or Remove Programs item in Control Panel.

Note When you remove this update, you may be prompted to insert the Microsoft Office 2003 CD in the CD drive. Additionally, you may not have the option to uninstall the update from the Add or Remove Programs item in Control Panel. There are several possible causes for this issue. For more information about the removal, see Microsoft Knowledge Base Article 903771.

Verifying that the Update Has Been Applied

• Microsoft Baseline Security Analyzer
  To verify that a security update has been applied to an affected system, you may be able to use the Microsoft Baseline Security Analyzer (MBSA) tool. See the section, Detection and Deployment Tools and Guidance, earlier in this bulletin for more information.

• File Version Verification
  Because there are several editions of Microsoft Windows, the following steps may be different on your system. If they are, see your product documentation to complete these steps.

  1. Click Start and then enter an update file name in the Start Search box.
  2. When the file appears under Programs, right-click the file name and click Properties.
  3. On the General tab, compare the file size with the file information tables provided in the bulletin KB article.
  4. You can also click the Details tab and compare information, such as file version and date modified, with the file information tables provided in the bulletin KB article.
  5. Finally, you can also click the Previous Versions tab and compare file information for the previous version of the file with the file information for the new, or updated, version of the file.

Microsoft Office 2007 (all editions)

Reference Table

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

Supported Security Update Installation Switches

Note You can combine these switches into one command. For backward compatibility, the security update also supports many of the setup switches that the earlier version of the Setup program uses. For more information about the supported installation switches, see Microsoft Knowledge Base Article 262841.

Removing the Update

To remove this security update, use the Add or Remove Programs item in Control Panel.

Note When you remove this update, you may be prompted to insert the 2007 Microsoft Office CD in the CD drive. Additionally, you may not have the option to uninstall the update from the Add or Remove Programs item in Control Panel. There are several possible causes for this issue. For more information about the removal, see Microsoft Knowledge Base Article 903771.

Verifying that the Update Has Been Applied

• Microsoft Baseline Security Analyzer
  To verify that a security update has been applied to an affected system, you may be able to use the Microsoft Baseline Security Analyzer (MBSA) tool. See the section, Detection and Deployment Tools and Guidance, earlier in this bulletin for more information.

• File Version Verification
  Because there are several editions of Microsoft Windows, the following steps may be different on your system. If they are, see your product documentation to complete these steps.

  1. Click Start and then enter an update file name in the Start Search box.
  2. When the file appears under Programs, right-click the file name and click Properties.
  3. On the General tab, compare the file size with the file information tables provided in the bulletin KB article.
     Note Depending on the edition of the operating system, or the programs that are installed on your system, some files that are listed in the file information table may not be installed.
  4. You can also click the Details tab and compare information, such as file version and date modified, with the file information tables provided in the bulletin KB article.
     Note Attributes other than the file version may change during installation. Comparing other file attributes to the information in the file information table is not a supported method of verifying that the update has been applied. Also, in certain cases, files may be renamed during installation. If the file or version information is not present, use one of the other available methods to verify update installation.
  5. Finally, you can also click the Previous Versions tab and compare file information for the previous version of the file with the file information for the new, or updated, version of the file.

Microsoft Office 2010 (all editions)

Reference Table

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

Supported Security Update Installation Switches

Note You can combine these switches into one command. For backward compatibility, the security update also supports many of the setup switches that the earlier version of the Setup program uses. For more information about the supported installation switches, see Microsoft Knowledge Base Article 262841.

Removing the Update

To remove this security update, use the Add or Remove Programs item in Control Panel.

Note When you remove this update, you may be prompted to insert the 2007 Microsoft Office CD in the CD drive. Additionally, you may not have the option to uninstall the update from the Add or Remove Programs item in Control Panel. There are several possible causes for this issue. For more information about the removal, see Microsoft Knowledge Base Article 903771.

Verifying that the Update Has Been Applied

• Microsoft Baseline Security Analyzer
  To verify that a security update has been applied to an affected system, you may be able to use the Microsoft Baseline Security Analyzer (MBSA) tool. See the section, Detection and Deployment Tools and Guidance, earlier in this bulletin for more information.

• File Version Verification
  Because there are several editions of Microsoft Windows, the following steps may be different on your system. If they are, see your product documentation to complete these steps.

  1. Click Start and then enter an update file name in the Start Search box.
  2. When the file appears under Programs, right-click the file name and click Properties.
  3. On the General tab, compare the file size with the file information tables provided in the bulletin KB article.
     Note Depending on the edition of the operating system, or the programs that are installed on your system, some files that are listed in the file information table may not be installed.
  4. You can also click the Details tab and compare information, such as file version and date modified, with the file information tables provided in the bulletin KB article.
     Note Attributes other than the file version may change during installation. Comparing other file attributes to the information in the file information table is not a supported method of verifying that the update has been applied. Also, in certain cases, files may be renamed during installation. If the file or version information is not present, use one of the other available methods to verify update installation.
  5. Finally, you can also click the Previous Versions tab and compare file information for the previous version of the file with the file information for the new, or updated, version of the file.

Microsoft Visual Basic for Applications

Reference Table

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

Deployment Information

Installing the Update

You can install the update from the appropriate download link in the Affected and Non-Affected Software section. If you installed your application from a server location, the server administrator must instead update the server location with the administrative update and deploy that update to your system.

For more information about the terminology that appears in this bulletin, such as hotfix, see Microsoft Knowledge Base Article 824684.

This security update supports the following setup switches.

Supported Security Update Installation Switches

Note You can combine these switches into one command.

Removing the Update

After you install the update, you cannot remove it.

Verifying that the Update Has Been Applied

• Microsoft Baseline Security Analyzer
  To verify that a security update has been applied to an affected system, you may be able to use the Microsoft Baseline Security Analyzer (MBSA) tool. See the section, Detection and Deployment Tools and Guidance, earlier in this bulletin for more information.

• File Version Verification
  Note Because there are several versions and editions of Microsoft Windows, the following steps may be different on your system. If they are, see your product documentation to complete these steps.

  1. Click Start, and then click Search.

  2. In the Search Results pane, click All files and folders under Search Companion.

  3. In the All or part of the file name box, type a file name from the appropriate file information table, and then click Search.

  4. In the list of files, right-click a file name from the appropriate file information table, and then click Properties.
     Note Depending on the edition of the operating system, or the programs that are installed on your system, some of the files that are listed in the file information table may not be installed.

  5. On the Version tab, determine the version of the file that is installed on your system by comparing it to the version that is documented in the appropriate file information table.
     Note Attributes other than the file version may change during installation. Comparing other file attributes to the information in the file information table is not a supported method of verifying that the update has been applied. Also, in certain cases, files may be renamed during installation. If the file or version information is not present, use one of the other available methods to verify update installation.

Other Information

Acknowledgments

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

• Bai Haowen of Huawei Security Labs for reporting the Visual Basic for Applications Insecure Library Loading Vulnerability (CVE-2012-1854)

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 websites provided by program partners, listed in Microsoft Active Protections Program (MAPP) Partners.

Support

How to obtain help and support for this security update

• Help installing updates: Support for Microsoft Update
• Security solutions for IT professionals: TechNet Security Troubleshooting and Support
• Help protect your computer that is running Windows from viruses and malware: Virus Solution and Security Center
• Local support according to your country: International Support

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 (July 10, 2012): Bulletin published.
• V2.0 (November 13, 2012): Rereleased bulletin to replace the KB2598361 update with the KB2687626 update for Microsoft Office 2003 Service Pack 3 to address an issue with digital certificates described in Microsoft Security Advisory 2749655. See the update FAQ for details.

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