Security Bulletin

Microsoft Security Bulletin MS07-051 - Critical

Vulnerability in Microsoft Agent Could Allow Remote Code Execution (938827)

Published: September 11, 2007 | Updated: September 12, 2007

Version: 1.1

General Information

Executive Summary

This critical security update resolves a privately reported vulnerability. A remote code execution vulnerability exists in Microsoft Agent in the way that it handles certain specially crafted URLs. The vulnerability could allow an attacker to remotely execute code on 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 is a critical security update for Microsoft Windows 2000 Service Pack 4. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerability by changing the way Microsoft Agent handles specially crafted URLs. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection for the vulnerability entry under the next section, Vulnerability Information.

Recommendation. Microsoft recommends that customers apply the update immediately.

Known Issues. None

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

Non-Affected Software

Frequently Asked Questions (FAQ) Related to This Security Update

I have the same binary version that is updated by this release, but have software listed in the non-affected section. Why is the listed non-affected software not vulnerable to the same underlying issue?
While agentdpv.dll, version 2.0.0.3426 is also distributed with the software editions identified in the Non-Affected Software section of the bulletin they are not affected as a result of security improvements specific to those platforms. Standard Microsoft Detection and Deployment resources listed in the Update Section of the bulletin will only identify and distribute this update to the Windows 2000 operating systems.

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.

Vulnerability Information

Severity Ratings and Vulnerability Identifiers

Agent Remote Code Execution Vulnerability - CVE-2007-3040

A remote code execution vulnerability exists in Microsoft Agent in the way that it handles certain specially crafted URLs. The vulnerability could allow an attacker to remotely execute code on 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.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2007-3040.

Mitigating Factors for Agent Remote Code Execution Vulnerability - CVE-2007-3040

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 have to 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 a malicious Web site. Instead, an attacker would have to persuade them to visit the Web site, typically by getting them to click a link that takes them 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 Restricted sites zone helps reduce attacks that could try to exploit this vulnerability by preventing ActiveX controls from being used when reading HTML e-mail messages. However, if a user clicks a link in an e-mail message, they could still be vulnerable to this issue through the Web-based attack scenario.
• By default, all supported versions of Microsoft Outlook and Microsoft Outlook Express open HTML e-mail messages in the Restricted sites zone. The Restricted sites zone helps reduce attacks that could try to exploit this vulnerability by preventing Active Scripting and ActiveX controls from being used when reading HTML e-mail. However, if a user clicks on a link within an e-mail they could still be vulnerable to this issue through the Web-based attack scenario.

Workarounds for Agent Remote Code Execution Vulnerability - CVE-2007-3040

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:

• Temporarily prevent the Agent ActiveX control from running in Internet Explorer

  You can help prevent attempts to instantiate this ActiveX control in Internet Explorer by setting the kill bit for the control in the registry.

  Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use the Registry Editor at your own risk.

  For detailed steps that you can use to prevent a control from running in Internet Explorer, see Microsoft Knowledge Base Article 240797. Follow these steps in this article to create a Compatibility Flags value in the registry to prevent a COM object from being instantiated in Internet Explorer.

  To set the kill bit for a CLSID with a value of {D45FD31B-5C6E-11D1-9EC1-00C04FD7081F}, paste the following text in a text editor such as Notepad. Then, save the file by using the .reg file name extension.

  Windows Registry Editor Version 5.00
  [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{D45FD31B-5C6E-11D1-9EC1-00C04FD7081F}]

  "Compatibility Flags"=dword:00000400

  [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{F5BE8BD2-7DE6-11D0-91FE-00C04FD701A5}]

  "Compatibility Flags"=dword:00000400

  [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{4BAC124B-78C8-11D1-B9A8-00C04FD97575}]

  "Compatibility Flags"=dword:00000400

  [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{D45FD31D-5C6E-11D1-9EC1-00C04FD7081F}]

  "Compatibility Flags"=dword:00000400

  [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{D45FD31E-5C6E-11D1-9EC1-00C04FD7081F}]

  "Compatibility Flags"=dword:00000400

  You can apply this .reg file to individual systems by double-clicking it. You can also apply it across domains by using Group Policy. For more information about Group Policy, visit the following Microsoft Web sites:

  • Group Policy collection
  • What is Group Policy Object Editor?
  • Core Group Policy tools and settings

  Note You must restart Internet Explorer for your changes to take effect.

  Impact of workaround: Web sites that use the Microsoft Agent ActiveX Control will no longer work correctly via Internet Explorer.

• Unregister AgentSvr.exe

  Enter the following at a command line or in a logon or machine startup script:

  %windir%\msagent\agentsvr.exe /unregserver

  Impact of workaround: Microsoft Agent will no longer work.

• Configure Internet Explorer to prompt before running ActiveX Controls or disable ActiveX Controls in the Internet and Local intranet security zone.

  You can help protect against this vulnerability by changing your Internet Explorer settings to prompt before running ActiveX controls. To do this, follow these steps:

  1. In Internet Explorer, click Internet Options on the Tools menu.
  2. Click the Security tab.
  3. Click Internet, and then click Custom Level.
  4. Under Settings, in the ActiveX controls and plug-ins section, under Run ActiveX controls and plug-ins, click Prompt or Disable, and then click OK.
  5. Click Local intranet, and then click Custom Level.
  6. Under Settings, in the ActiveX controls and plug-ins section, under Run ActiveX controls and plug-ins, click Prompt or Disable, and then click OK.
  7. Click OK two times to return to Internet Explorer.

  Impact of Workaround: There are side effects to prompting before running ActiveX controls. Many Web sites that are on the Internet or on an intranet use ActiveX to provide additional functionality. For example, an online e-commerce site or banking site may use ActiveX controls to provide menus, ordering forms, or even account statements. Prompting before running ActiveX controls is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run ActiveX controls. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to the Internet Explorer Trusted sites zone”.

  Add sites that you trust to the Internet Explorer Trusted sites zone

  After you set Internet Explorer to require a prompt before it runs ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to the Internet Explorer Trusted sites zone. This will allow you to continue to use trusted Web sites exactly as you do today, while helping to protect you from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.

  To do this, follow these steps:

  1. In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.
  2. In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.
  3. If you want to add sites that do not require an encrypted channel, click to clear the Require server verification (https:) for all sites in this zone check box.
  4. In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.
  5. Repeat these steps for each site that you want to add to the zone.
  6. Click OK two times to accept the changes and return to Internet Explorer.

  Note Add any sites that you trust not to take malicious action on your computer. To continue receiving security updates from Microsoft, add are *.windowsupdate.microsoft.com and *.update.microsoft.com. These are the sites that will host the update, and you must have an ActiveX Control to install the update.

• Set Internet and Local intranet security zone settings to “High” to prompt before running ActiveX Controls and Active Scripting in these zones

  You can help protect against this vulnerability by changing your settings for the Internet security zone to prompt before running ActiveX controls. You can do this by setting your browser security to High.

  To raise the browsing security level in Microsoft Internet Explorer, follow these steps:

  1. On the Internet Explorer Tools menu, click Internet Options.
  2. In the Internet Options dialog box, click the Security tab, and then click the Internet icon.
  3. Under Security level for this zone, move the slider to High. This sets the security level for all Web sites you visit to High.

  Note If no slider is visible, click Default Level, and then move the slider to High.

  Note Setting the level to High may cause some Web sites to work incorrectly. If you have difficulty using a Web site after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly even with the security setting set to High.

  Impact of Workaround: There are side effects to prompting before running ActiveX controls. Many Web sites that are on the Internet or on an intranet use ActiveX to provide additional functionality. For example, an online e-commerce site or banking site may use ActiveX controls to provide menus, ordering forms, or even account statements. Prompting before running ActiveX controls is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click Yes to run ActiveX controls. If you do not want to be prompted for all these sites, use the steps outlined in “Add sites that you trust to the Internet Explorer Trusted sites zone”.

  Add sites that you trust to the Internet Explorer Trusted sites zone

  After you set Internet Explorer to require a prompt before it runs ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to the Internet Explorer Trusted sites zone. This will allow you to continue to use trusted Web sites exactly as you do today, while helping to protect you from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.

  To do this, follow these steps:

  1. In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.
  2. In the Select a Web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.
  3. If you want to add sites that do not require an encrypted channel, click to clear the Require server verification (https:) for all sites in this zone check box.
  4. In the Add this Web site to the zone box, type the URL of a site that you trust, and then click Add.
  5. Repeat these steps for each site that you want to add to the zone.
  6. Click OK two times to accept the changes and return to Internet Explorer.

  Note Add any sites that you trust not to take malicious action on your computer. To continue receiving security updates from Microsoft, add are *.windowsupdate.microsoft.com and *.update.microsoft.com. These are the sites that will host the update, and you must have an ActiveX Control to install the update.

FAQ for Agent Remote Code Execution Vulnerability - CVE-2007-3040

What is the scope of the vulnerability?
A remote code execution vulnerability exists in Microsoft Agent in the way that it handles certain specially crafted URLs. An attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

What causes the vulnerability?
Supplying a specially crafted URL to the Microsoft Agent ActiveX control could corrupt system memory so that an attacker could execute arbitrary code.

What is Microsoft Agent?
Microsoft Agent is a component of the Microsoft Windows operating system that uses interactive animated characters to guide users and can make using and learning to use a computer easier. For more information, see the Microsoft Agent Web site.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability 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.

Who could exploit the vulnerability?
In a Web-based attack scenario, an attacker would have to host a Web site that contains a Web page that is used to attempt to 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?
This vulnerability requires that a user is logged on and visits a Web site for any malicious action to occur. Any systems where Internet Explorer is used frequently, such as workstations or terminal servers, are at the most risk from this vulnerability.

What does the update do?
The update removes the vulnerability by changing the way Microsoft Agent handles specially crafted URLs.

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 computers 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, Windows Update, and Office Update. Security updates are also available at the Microsoft Download Center. You can find them most easily by doing a keyword search for "security_patch." Finally, security updates can be downloaded from the Windows Update Catalog. For more information about the Windows Update Catalog, see Microsoft Knowledge Base Article 323166.

Detection and Deployment Guidance

Microsoft has provided detection and deployment guidance for this month’s security updates. This guidance will also help IT professionals understand how they can use various tools to help deploy the security update, such as Windows Update, Microsoft Update, Office Update, the Microsoft Baseline Security Analyzer (MBSA), the Office Detection Tool, Microsoft Systems Management Server (SMS), the Extended Security Update Inventory Tool, and the Enterprise Update Scan Tool (EST). For more information, see Microsoft Knowledge Base Article 910723.

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

For more information about MBSA, visit the MBSA Web site. For more information about the software that Microsoft Update and MBSA 2.0 currently do not detect, see Microsoft Knowledge Base Article 895660.

Windows Server Update Services

By using Windows Server Update Services (WSUS), administrators can deploy the latest critical updates and security updates for Microsoft Windows 2000 operating systems and later, Office XP and later, Exchange Server 2003, and SQL Server 2000 to Microsoft Windows 2000 and later operating systems. 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.

SMS 2.0 and SMS 2003 Software Update Services (SUS) Feature Pack can use MBSA 1.2.1 for detection and therefore have the same limitation that is listed earlier in this bulletin related to programs that MBSA 1.2.1 does not detect.

For SMS 2.0, the SMS SUS Feature Pack, which includes the Security Update Inventory Tool (SUIT), can be used by SMS to detect security updates. SMS SUIT uses the MBSA 1.2.1 engine for detection. For more information about SUIT, visit the following Microsoft Web site. For more information about the limitations of SUIT, see Microsoft Knowledge Base Article 306460. The SMS SUS Feature Pack also includes the Microsoft Office Inventory Tool to detect required updates for Microsoft Office applications.

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, visit the following Microsoft Web site. SMS 2003 can also use the Microsoft Office Inventory Tool to detect required updates for Microsoft Office applications.

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

Security Update Deployment

Affected Software

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

Microsoft Windows 2000 (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.

File Information

The English version of this security update has the file attributes that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

For all supported editions of Microsoft Windows 2000:

Note For a complete list of supported versions and editions, see the Support Lifecycle Index. For a complete list of service packs, see Lifecycle Supported Service Packs. For more information on the support lifecycle policy, see Microsoft Support Lifecycle.

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.

If you have previously installed a hotfix to update one of these files, the installer copies the RTMQFE, SP1QFE, or SP2QFE files to your system. Otherwise, the installer copies the RTMGDR, SP1GDR, or SP2GDR files to your system. Security updates may not contain all variations of these files. For more information about this behavior, see Microsoft Knowledge Base Article 824994.

For more information about the installer, visit the Microsoft TechNet Web site.

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.

Note You can combine these switches into one command. For backward compatibility, the security update also supports 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

This security update supports the following setup switches.

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 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.

• Registry Key Verification

  You may also be able to verify the files that this security update has installed by reviewing the registry keys listed in the Reference Table in this section.

  These registry keys may not contain a complete list of installed files. Also, these registry keys may not be created correctly when an administrator or an OEM integrates or slipstreams this security update into the Windows installation source files.

Other Information

Acknowledgments

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

• The Vulnerability Research team of Assurent Secure Technologies for reporting the Agent Remote Code Execution Vulnerability - CVE-2007-3040
• Yamata Li of Palo Alto Networks for reporting the Agent Remote Code Execution Vulnerability - CVE-2007-3040
• An anonymous researcher working with VeriSign iDefense VCP for reporting the Agent Remote Code Execution Vulnerability - CVE-2007-3040

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.

Revisions

• V1.0 (September 11, 2007): Bulletin published.

  V1.1 (September 12, 2007): Bulletin updated to include FAQ as to why up-level platforms are not affected by the vulnerability addressed by this bulletin.

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