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Microsoft Security Bulletin MS06-031 - Critical

Vulnerability in RPC Mutual Authentication Could Allow Spoofing (917736)

Published: June 13, 2006

Version: 1.0

Summary

Who Should Read this Document: Customers who use Microsoft Windows

Impact of Vulnerability: Spoofing

Maximum Severity Rating: Moderate

Recommendation: Customers should consider applying the security update

Security Update Replacement: None

Caveats: None

Tested Software and Security Update Download Locations:

Affected Software:

Non-Affected Software:

  • Microsoft Windows XP Service Pack 1 and Microsoft Windows XP Service Pack 2
  • Microsoft Windows XP Professional x64 Edition
  • Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service Pack 1
  • Microsoft Windows Server 2003 for Itanium-based Systems and Microsoft Windows Server 2003 with SP1 for Itanium-based Systems
  • Microsoft Windows Server 2003 x64 Edition
  • Microsoft Windows 98, Microsoft Windows 98 Second Edition (SE), and Microsoft Windows Millennium Edition (Me)

The software in this list has been tested to determine whether the versions are affected. Other versions either no longer include security update support or may not be affected. To determine the support life cycle for your product and version, visit the Microsoft Support Lifecycle Web site.

General Information

Executive Summary:

This update resolves a newly discovered, privately reported vulnerability. A spoofing vulnerability exists in the RPC service that could enable an attacker to spoof trusted network resource. The vulnerability is documented in the "Vulnerability Details" section of this bulletin.

Severity Ratings and Vulnerability Identifiers:

Vulnerability IdentifiersImpact of VulnerabilityWindows 2000
RPC Mutual Authentication Vulnerability - CVE-2006-2380SpoofingModerate

This assessment is based on the types of systems that are affected by the vulnerability, their typical deployment patterns, and the effect that exploiting the vulnerability would have on them.

Extended security update support for Microsoft Windows 2000 Service Pack 3 ended on June 30, 2005. I am still using one of these operating systems, what should I do?
Windows 2000 Service Pack 3 has reached its end of life cycle. It should be a priority for customers who have this operating system version to migrate to supported versions to prevent potential exposure to vulnerabilities. For more information about the Windows Product Lifecycle, visit the following Microsoft Support Lifecycle Web site. For more information about the extended security update support period for this operating system version, visit the Microsoft Product Support Services Web site.

Customers who require custom support for these products 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.

Can I use the Microsoft Baseline Security Analyzer (MBSA) to determine whether this update is required?
The following table provides the MBSA detection summary for this security update.

SoftwareMBSA 1.2.1MBSA 2.0
Microsoft Windows 2000 Service Pack 4YesYes

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

Can I use Systems Management Server (SMS) to determine whether this update is required?
The following table provides the SMS detection summary for this security update.

SoftwareSMS 2.0SMS 2003
Microsoft Windows 2000 Service Pack 4YesYes

SMS uses MBSA for detection. Therefore, SMS has the same limitation that is listed earlier in this bulletin related to software that MBSA does not detect.

For SMS 2.0, the SMS SUS Feature Pack, which includes the Security Update Inventory Tool, can be used by SMS to detect security updates. SMS SUIT uses the MBSA 1.2.1 engine for detection. For more information about the Security Update Inventory Tool, visit the following Microsoft Web site. For more information about the limitations of the Security Update Inventory Tool, 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 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 Inventory Tool for Microsoft Updates, 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.

RPC Mutual Authentication Vulnerability - CVE-2006-2380:

There is a spoofing vulnerability in the way that RPC handles mutual authentication. This vulnerability could allow an attacker to persuade a user to connect to a malicious RPC server which appears to be valid.

Mitigating Factors for RPC Mutual Authentication Vulnerability - CVE-2006-2380:

  • An attacker would have no way to force users to connect to a malicious RPC server.

Workarounds for RPC Mutual Authentication Vulnerability - CVE-2006-2380:

Microsoft has tested the following workarounds. Although these workarounds will not correct the underlying vulnerability, they help block known attack vectors. When a workaround reduces functionality, it is identified in the following section.

FAQ for RPC Mutual Authentication Vulnerability - CVE-2006-2380:

What is the scope of the vulnerability?
This is a spoofing vulnerability which affects custom RPC applications acting as RPC clients using SSL with mutual authentication option. An attacker who successfully exploited this vulnerability could impersonate a valid RPC server.

What causes the vulnerability?
The affected product does not correctly validate the identity of RPC server while utilizing mutual authentication over Secure Socket Layer (SSL).

What is Mutual Authentication?
Both the client and the server machines will exchange credentials to verify identities before data is exchanged.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could impersonate a valid service.

Who could exploit the vulnerability?
An attacker would first need to persuade a user to connect to a resource which requires mutual authentication using Secure Sockets Layer (SSL). The attacker could then impersonate a valid RPC server. An attacker would have no way to force users to visit the RPC server.

How could an attacker exploit the vulnerability?
An attacker could try to exploit the vulnerability by persuading a user to connect to an RPC service which has been configured to impersonate a valid server.

What systems are primarily at risk from the vulnerability?
Workstations and servers are at risk from this vulnerability.

Could the vulnerability be exploited over the Internet?
Yes. An attacker could try to exploit this vulnerability over the Internet. Firewall best practices and standard default firewall configurations can help protect against attacks that originate from the Internet. Microsoft has provided information about how you can help protect your PC. End users can visit the Protect Your PC Web site. IT professionals can visit the Security Guidance Center Web site.

What does the update do?
The update removes the vulnerability by modifying the way that RPC handles mutual authentication.

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.

Affected Software:

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

Windows 2000 (all versions)

Prerequisites
For Windows 2000, this security update requires Service Pack 4 (SP4). For Small Business Server 2000, this security update requires Small Business Server 2000 Service Pack 1a (SP1a) or Small Business Server 2000 running with Windows 2000 Server Service Pack 4 (SP4).

The software that is listed has been tested to determine whether the versions are affected. Other versions either no longer include security update support or may not be affected. To determine the support life cycle for your product and version, visit the Microsoft Support Lifecycle Web site.

For more information about how to obtain the latest service pack, see Microsoft Knowledge Base Article 260910.

Inclusion in Future Service Packs:
The update for this issue may be included in a future Update Rollup.

Installation Information

This security update supports the following setup switches.

Supported Security Update Installation Switches
SwitchDescription
/help Displays the command-line options.
Setup Modes
/passive Unattended Setup mode. No user interaction is required, but installation status is displayed. If a restart is required at the end of setup, a dialog box will be presented to the user with a timer warning that the computer will restart in 30 seconds.
/quiet Quiet mode. This is the same as unattended mode, but no status or error messages are displayed.
Restart Options
/norestart Does not restart when installation has completed.
/forcerestart Restarts the computer after installation and forces other applications to close at shutdown without saving open files first.
/warnrestart[:x] Displays a dialog box with a timer warning the user that the computer will restart in x seconds. (The default setting is 30 seconds.) Intended for use with the /quiet switch or the /passive switch.
/promptrestart Display a dialog box prompting the local user to allow a restart.
Special Options
/overwriteoem Overwrites OEM files without prompting.
/nobackup Does not back up files needed for uninstallation.
/forceappsclose Forces other programs to close when the computer shuts down.
/log:path Allows the redirection of installation log files.
/integrate:path Integrates the update into the Windows source files. These files are located at the path that is specified in the switch.
/extract[:path] Extracts files without starting the Setup program.
/ER Enables extended error reporting.
/verbose Enables verbose logging. During installation, creates %Windir%\CabBuild.log. This log details the files that are copied. Using this switch may cause the installation to proceed more slowly.

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. For more information about the Update.exe 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.

Deployment Information

To install the security update without any user intervention, use the following command at a command prompt for Windows 2000 Service Pack 4:

Windows2000-kb917736-x86-enu /quiet

Note Use of the /quiet switch will suppress all messages. This includes suppressing failure messages. Administrators should use one of the supported methods to verify the installation was successful when they use the /quiet switch. Administrators should also review the KB917736.log file for any failure messages when they use this switch.

To install the security update without forcing the system to restart, use the following command at a command prompt for Windows 2000 Service Pack 4:

Windows2000-kb917736-x86-enu /norestart

For more information about how to deploy this security update with Software Update Services, visit the Software Update Services Web site. For more information about how to deploy this security update using Windows Server Update Services, visit the Windows Server Update Services Web site. This security update will also be available through the Microsoft Update Web site.

Restart Requirement

You must restart your system after you apply this security update.

Removal Information

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

System administrators can also use the Spuninst.exe utility to remove this security update. The Spuninst.exe utility is located in the %Windir%\$NTUninstallKB917736$\Spuninst folder.

Supported Spuninst.exe Switches
SwitchDescription
/help Displays the command-line options.
Setup Modes
/passive Unattended Setup mode. No user interaction is required, but installation status is displayed. If a restart is required at the end of setup, a dialog box will be presented to the user with a timer warning that the computer will restart in 30 seconds.
/quiet Quiet mode. This is the same as unattended mode, but no status or error messages are displayed.
Restart Options
/norestart Does not restart when installation has completed.
/forcerestart Restarts the computer after installation and forces other applications to close at shutdown without saving open files first.
/warnrestart[:x] Displays a dialog box with a timer warning the user that the computer will restart in x seconds. (The default setting is 30 seconds.) Intended for use with the /quiet switch or the /passive switch.
/promptrestart Display a dialog box prompting the local user to allow a restart.
Special Options
/forceappsclose Forces other programs to close when the computer shuts down.
/log:path Allows the redirection of installation log files.

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.

Windows 2000 Service Pack 4 and Small Business Server 2000:

File NameVersionDateTimeSize
Rpcrt4.dll5.0.2195.708513-Apr-200617:47437,008

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 can use the Microsoft Baseline Security Analyzer (MBSA) tool. MBSA allows administrators to scan local and remote systems for missing security updates and for common security misconfigurations. For more information about MBSA, visit the Microsoft Baseline Security Analyzer Web site.

  • File Version Verification

    Note Because there are several versions of Microsoft Windows, the following steps may be different on your computer. 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 version of the operating system or programs installed, 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 computer 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 following registry key:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows 2000\SP5\KB917736\Filelist

    Note This registry key may not contain a complete list of installed files. Also, this registry key may not be created correctly when an administrator or an OEM integrates or slipstreams the 917736 security update into the Windows installation source files.

Other Information

Acknowledgments

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

  • Konstantin Topanov of Symantec for reporting the RPC Mutual Authentication Vulnerability (CVE-2006-2380).

Obtaining Other Security Updates:

Updates for other security issues are available at the following locations:

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.

Security Resources:

Software Update Services:

By using Microsoft Software Update Services (SUS), administrators can quickly and reliably deploy the latest critical updates and security updates to Windows 2000 and Windows Server 2003-based servers, and to desktop systems that are running Windows 2000 Professional or Windows XP Professional.

For more information about how to deploy security updates by using Software Update Services, visit the Software Update Services Web site.

Windows Server Update Services:

By using Windows Server Update Services (WSUS), administrators can quickly and reliably 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 onto Windows 2000 and later operating systems.

For more information about how to deploy security updates using Windows Server Update Services, visit the Windows Server Update Services Web site.

Systems Management Server:

Microsoft Systems Management Server (SMS) delivers a highly configurable enterprise solution for managing updates. By using SMS, administrators can identify Windows-based systems that require security updates and can perform controlled deployment of these updates throughout the enterprise with minimal disruption to end users. For more information about how administrators can use SMS 2003 to deploy security updates, visit the SMS 2003 Security Patch Management Web site. SMS 2.0 users can also use Software Updates Service Feature Pack to help deploy security updates. For information about SMS, visit the SMS Web site.

Note SMS uses the Microsoft Baseline Security Analyzer, the Microsoft Office Detection Tool, and the Enterprise Update Scanning Tool to provide broad support for security bulletin update detection and deployment. Some software updates may not be detected by these tools. Administrators can use the inventory capabilities of the SMS in these cases to target updates to specific systems. For more information about this procedure, visit the following Web site. Some security updates require administrative rights following a restart of the system. Administrators can use the Elevated Rights Deployment Tool (available in the SMS 2003 Administration Feature Pack and in the SMS 2.0 Administration Feature Pack) to install these updates.

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 (June 13, 2006): Bulletin published.

Built at 2014-04-18T13:49:36Z-07:00

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