Security Bulletin

Microsoft Security Bulletin MS09-049 - Critical

Vulnerability in Wireless LAN AutoConfig Service Could Allow Remote Code Execution (970710)

Published: September 08, 2009 | Updated: September 09, 2009

Version: 1.1

General Information

Executive Summary

This security update resolves a privately reported vulnerability in Wireless LAN AutoConfig Service. The vulnerability could allow remote code execution if a client or server with a wireless network interface enabled receives specially crafted wireless frames. Systems without a wireless card enabled are not at risk from this vulnerability.

This security update is rated Critical for supported editions of Windows Vista and Important for supported editions of Windows Server 2008. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerability by extending the Wireless LAN AutoConfig service to properly validate wireless frames prior to processing them. 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. The majority of customers have automatic updating enabled and 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 and install this update manually. For information about specific configuration options in automatic updating, see Microsoft Knowledge Base Article 294871.

For administrators and enterprise installations, or end users who want to install this security update manually, Microsoft recommends that customers apply the update immediately 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. None

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

*Windows Server 2008 Server Core installation not affected. The vulnerability addressed by this update does not affect supported editions of Windows Server 2008 if Windows Server 2008 was installed using the Server Core installation option. For more information on this installation option, see Server Core. Note that the Server Core installation option does not apply to certain editions of Windows Server 2008; see Compare Server Core Installation Options.

Non-Affected Software

Frequently Asked Questions (FAQ) Related to This Security Update

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

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 Microsoft Support Lifecycle. For more information about the extended security update support period for these software versions or editions, visit Microsoft Product Support Services.

Customers who require custom support for older releases 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 Microsoft Worldwide Information, 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.

Vulnerability Information

Severity Ratings and Vulnerability Identifiers

The following severity ratings assume the potential maximum impact of the vulnerability. For information regarding the likelihood, within 30 days of this security bulletin's release, of the exploitability of the vulnerability in relation to its severity rating and security impact, please see the Exploitability Index in the September bulletin summary. For more information, see Microsoft Exploitability Index.

*Windows Server 2008 Server Core installation not affected. The vulnerability addressed by this update does not affect supported editions of Windows Server 2008 if Windows Server 2008 was installed using the Server Core installation option. For more information on this installation option, see Server Core. Note that the Server Core installation option does not apply to certain editions of Windows Server 2008; see Compare Server Core Installation Options.

Wireless Frame Parsing Remote Code Execution Vulnerability - CVE-2009-1132

A remote code execution vulnerability exists in the way that the Wireless LAN AutoConfig Service (wlansvc) parses specific frames received on the wireless network. This vulnerability could allow remote code execution if a client or server with a wireless network interface enabled receives specially crafted wireless frames. An attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2009-1132.

Mitigating Factors for Wireless Frame Parsing Remote Code Execution Vulnerability - CVE-2009-1132

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:

• Systems without a wireless card enabled are not at risk from this vulnerability.

Workarounds for Wireless Frame Parsing Remote Code Execution Vulnerability - CVE-2009-1132

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:

• Unregister Wlansvc

  To modify the registry key, perform the following steps:

  Note Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or view the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe.

  Using the Interactive Method

  1. Click Start, click Run, type Regedit in the Open box, and then click OK.
  2. Locate and then click the following registry subkey:
     HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services
  3. Click Wlansvc.
  4. Click the File menu and select Export.
  5. In the Export Registry File dialog box, enter Wlansvc_configuration_backup.reg and click Save.
     Note This will create a backup of this registry key in the My Documents folder by default.
  6. Double-click the Start value and change the Value data field to 4.
  7. Click OK.
  8. Run the following command from a command prompt as an administrator:

  sc stop Wlansvc

  Using a Managed Deployment Script

  1. Create a backup copy of the registry keys by using a managed deployment script that contains the following commands:
     Regedit.exe /e Wlansvc_configuration_backup.reg
     HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Wlansvc
  2. Next, save the following to a file with a .REG extension, such as Disable_Wlansvc.reg:
     Windows Registry Editor Version 5.00
     [HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Wlansvc]
     "Start"=dword:00000004
  3. Run the above registry script on the target machine with the following command:
     Regedit.exe /s Disable_Wlansvc.reg
  4. Run the following command from a command prompt as an administrator:
     sc stop Wlansvc

  Impact of workaround. Wireless networking will not be available.

  How to undo the workaround:

  Using the Interactive Method

  1. Click Start, click Run, type Regedit in the Open box, and then click OK.
  2. Click the File menu and select Import.
  3. In the Import Registry File dialog box, select Wlansvc_configuration_backup.reg and click Open.

  Using a Managed Deployment Script

  Restore the original state by running the following command:
  Regedit.exe /s Wlansvc_configuration_backup.reg

FAQ for Wireless Frame Parsing Remote Code Execution Vulnerability - CVE-2009-1132

What is the scope of the vulnerability? 
This vulnerability affects Windows clients and servers that use wireless networking and are within the range of a wireless transmitter operated by an attacker. 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; view, change, or delete data; or create new accounts with full user rights.

What causes the vulnerability? 
The vulnerability is caused by lack of validation of part of a specific malformed frame transmitted by a remote wireless transmitter. This could lead to a heap overflow situation that may result in arbitrary code execution.

What is the Wireless LAN AutoConfig Service (Wlansvc)? 
WLAN AutoConfig is a service that configures wireless security and connectivity settings. WLAN AutoConfig configures Institute of Electrical and Electronics Engineers (IEEE) 802.11 wireless adapters for connectivity to ad-hoc wireless networks, small-office wireless infrastructure networks, and for networks that provide 802.1x-authenticated network access. When enabled, WLAN AutoConfig settings apply to all IEEE 802.11 wireless network adapters that are installed on a computer.

What might an attacker use the vulnerability to do? 
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.

How could an attacker exploit the vulnerability? 
An attacker could deploy a wireless transmitter that transmits maliciously crafted frames to trigger the vulnerability.

What systems are primarily at risk from the vulnerability? 
All clients and servers with an enabled wireless network interface are at risk from this vulnerability.

What does the update do? 
This security update resolves the vulnerability by extending the Wireless LAN AutoConfig service to properly validate wireless frames prior to processing them.

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

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited? 
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers and had not seen any examples of proof of concept code published when this security bulletin was originally issued.

Update Information

Detection and Deployment Tools and Guidance

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 Web site 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."

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.

Note Microsoft discontinued support for Office Update and the Office Update Inventory Tool as of August 1, 2009. To continue getting the latest updates for Microsoft Office products, use Microsoft Update. For more information, see About Microsoft Office Update: Frequently Asked Questions.

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.

For more information about MBSA 2.1, see MBSA 2.1 Frequently Asked Questions.

Windows Server Update Services

By using Windows Server Update Services (WSUS), administrators can deploy the latest critical updates and security updates for Windows 2000 operating systems and later, Office XP and later, Exchange Server 2003, and SQL Server 2000. For more information about how to deploy this security update using Windows Server Update Services, visit the Windows Server Update Services Web site.

Systems Management Server

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

For SMS 2.0 and SMS 2003, the Security Update Inventory Tool (SUIT) can be used by SMS to detect security updates. See also Downloads for Systems Management Server 2.0.

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 2007 uses WSUS 3.0 for detection of updates. For more information about Configuration Manager 2007 Software Update Management, visit System Center Configuration Manager 2007.

Note for Windows Vista and Windows Server 2008 Microsoft Systems Management Server 2003 with Service Pack 3 includes support for Windows Vista and Windows Server 2008 manageability.

For more information about SMS, visit the SMS Web site.

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

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 Microsoft 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:

Windows Vista (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.

Deployment Information

Installing the Update

When you install this security update, the installer checks whether one or more of the files that are being updated on your system have previously been updated by a Microsoft hotfix.

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 For more information about the wusa.exe installer, see Microsoft Knowledge Base Article 934307.

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 Start Search.
  2. When the file appears under Programs, right-click on the file name and click Properties.
  3. Under the General tab, compare the file size with the file information tables provided in the bulletin KB article.
  4. You may also click on 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 may also click on 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.

Windows Server 2008 (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.

Deployment Information

Installing the Update

When you install this security update, the installer checks whether one or more of the files that are being updated on your system have previously been updated by a Microsoft hotfix.

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 For more information about the wusa.exe installer, see Microsoft Knowledge Base Article 934307.

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 Start Search.
  2. When the file appears under Programs, right-click on the file name and click Properties.
  3. Under the General tab, compare the file size with the file information tables provided in the bulletin KB article.
  4. You may also click on 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 may also click on 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.

Other Information

Microsoft Active Protections Program (MAPP)

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

Support

• Customers in the U.S. and Canada can receive technical support from Security Support or 1-866-PCSAFETY. There is no charge for support calls that are associated with security updates. For more information about available support options, see Microsoft Help and Support.
• International customers can receive support from their local Microsoft subsidiaries. There is no charge for support that is associated with security updates. For more information about how to contact Microsoft for support issues, visit the International Support Web site.

Disclaimer

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

Revisions

• V1.0 (September 8, 2009): Bulletin published.
• V1.1 (September 9, 2009): Revised the description for Wireless Frame Parsing Remote Code Execution Vulnerability (CVE-2009-1132) to clarify exploit conditions.

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