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Microsoft Security Bulletin MS04-029

Vulnerability in RPC Runtime Library Could Allow Information Disclosure and Denial of Service (873350)

Issued: October 12, 2004
Version: 1.0

Summary

Who should read this document: Customers who use Microsoft Windows

Impact of Vulnerability: Important

Maximum Severity Rating: Information Disclosure and Denial of Service

Recommendation: Customers should install the update at the earliest opportunity.

Security Update Replacement: This bulletin replaces several prior security updates. See the frequently asked questions (FAQ) section of this bulletin for the complete list.

Caveats: None

Tested Software and Security Update Download Locations:

Affected Software:

•	Microsoft Windows NT Server 4.0 Service Pack 6a – Download the update
•	Microsoft Windows NT Server 4.0 Terminal Server Edition Service Pack 6 – Download the update

Non-Affected Software:

•	Microsoft Windows 2000 Service Pack 3 and Microsoft Windows 2000 Service Pack 4
•	Microsoft Windows XP and Microsoft Windows XP Service Pack 1
•	Microsoft Windows XP Service Pack 2
•	Microsoft Windows XP 64-Bit Edition Service Pack 1
•	Microsoft Windows XP 64-Bit Edition Version 2003
•	Microsoft Windows Server 2003
•	Microsoft Windows Server 2003 64-Bit 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 if the versions are affected. Other versions either no longer include security update support or may not be affected. To determine the support lifecycle for your product and version, visit the following Microsoft Support Lifecycle Web site.

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General Information

Executive Summary

Executive Summary:

This update resolves a newly-discovered, privately reported vulnerability. The vulnerability is documented in the Vulnerability Details section of this bulletin.

An attacker who successfully exploited the vulnerability could cause the affected system to stop responding or could potentially read portions of active memory content.

We recommend that customers install the security update at the earliest opportunity.

Severity Ratings and Vulnerability Identifiers:

Vulnerability Identifiers	Impact of Vulnerability	Windows NT 4.0
RPC Runtime Library Vulnerability - CAN-2004-0569	Information Disclosure Denial of Service	Important

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.

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Frequently asked questions (FAQ) related to this security update

What updates does this release replace?
This security update replaces several prior security bulletins. The security bulletin IDs and operating systems that are affected are listed in the table below.

Bulletin ID	Windows NT 4.0	Windows 2000	Windows XP	Windows Server 2003
MS98-014	Replaced	Not Applicable	Not Applicable	Not Applicable
MS01-048	Replaced	Not Applicable	Not Applicable	Not Applicable
MS03-026	Replaced	Not Applicable	Not Applicable	Not Applicable
MS03-039	Replaced	Not Applicable	Not Applicable	Not Applicable
MS04-012	Not Replaced	Not Applicable	Not Applicable	Not Applicable

Note This security update does not replace any security updates that are provided as part of MS04-012. MS04-012 has only been documented in the above table for reference.

I'm still using Windows NT 4.0 Workstation, but extended security update support ended on June 30, 2004. What should I do?

Windows NT 4.0 Workstation reached the end of its extended support life cycle as previously documented. It should be a priority for customers who have this operating system version to migrate to supported operating system versions to prevent potential exposure to vulnerabilities. For more information about the Windows Product Life Cycle, 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 following Microsoft Product Support Services Web site.

Customers who require additional support for Windows NT Workstation 4.0 SP6a must contact their Microsoft account team representative, their Technical Account Manager, or the appropriate Microsoft partner representative for custom support options. Customers who do not have 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 phone numbers. When you call, ask to speak with the local Premier Support sales manager.

For more information, see the Windows Operating System FAQ.

Can I use the Microsoft Baseline Security Analyzer (MBSA) to determine if this update is required?
Yes. MBSA will determine if this update is required. For more information about MBSA, visit the MBSA Web site

Note After April 20, 2004, the Mssecure.xml file that is used by MBSA 1.1.1 and earlier versions is no longer being updated with new security bulletin data. Therefore, scans that are performed after that date with MBSA 1.1.1 or earlier will be incomplete. All users should upgrade to MBSA 1.2 because it provides more accurate security update detection and supports additional products. Users can download MBSA 1.2 from the MBSA Web site. For more information about MBSA support, visit the following Microsoft Baseline Security Analyzer 1.2 Q&A Web site.

Can I use Systems Management Server (SMS) to determine if this update is required?
Yes. SMS can help detect and deploy this security update. For information about SMS, visit the SMS Web site

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Vulnerability Details

RPC Runtime Library Vulnerability - CAN-2004-0569:

An information disclosure and denial of service vulnerability exists when the RPC Runtime Library processes specially crafted messages. An attacker who successfully exploited this vulnerability could potentially read portions of active memory or cause the affected system to stop responding.

Mitigating Factors for RPC Runtime Library Vulnerability - CAN-2004-0569:

•	Firewall best practices and standard default firewall configurations can help protect networks from attacks that originate outside the enterprise perimeter. Best practices recommend that systems that are connected to the Internet have a minimal number of ports exposed.

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Workarounds for RPC Runtime Library Vulnerability - CAN-2004-0569:

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

•

Block the following at the firewall:

•	UDP ports 135, 137, 138, and 445, and TCP ports 135, 139, 445, and 593
•	All unsolicited inbound traffic on ports greater than 1024
•	Any other specifically configured RPC port
•	If installed, COM Internet Services (CIS) or RPC over HTTP, which listen on ports 80 and 443

These ports are used to initiate a connection with RPC. Blocking them at the firewall will help prevent systems that are behind that firewall from attempts to exploit this vulnerability. Also, make sure that you block any other specifically configured RPC port on the remote system. We recommend that you block all unsolicited inbound communication from the Internet to help prevent attacks that may use other ports. For more information about the ports that RPC uses, visit the following Web site. For more information about how to disable CIS, see Microsoft Knowledge Base Article 825819.

•

Enable advanced TCP/IP filtering on systems that support this feature.

You can enable advanced TCP/IP filtering to block all unsolicited inbound traffic. For additional information about how to configure TCP/IP filtering, see Microsoft Knowledge Base Article 309798.

•

Block the affected ports by using IPSec on the affected systems.

Use Internet Protocol Security (IPSec) to help protect network communications. Detailed information about IPSec and how to apply filters is available in Microsoft Knowledge Base Articles 313190 and 813878.

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FAQ for RPC Runtime Library Vulnerability - CAN-2004-0569:

What is the scope of the vulnerability?
This is an information disclosure and denial of service vulnerability. An attacker who successfully exploited this vulnerability could potentially read portions of active memory or cause the affected system to stop responding.

What causes the vulnerability?
An unchecked buffer in the RPC Runtime Library.

What is Remote Procedure Call (RPC)?
Remote Procedure Call (RPC) is a protocol that the Windows operating system uses. RPC provides an interprocess communication mechanism that allows a program that is running on one system to access services seamlessly on another system. The protocol is derived from the Open Software Foundation (OSF) RPC protocol, with the addition of some Microsoft-specific extensions.

What is the RPC Runtime Library?
By default, the RPC Runtime Library is installed on all affected systems. The RPC Runtime Library provides services such as communication services, directory services, and security services to application developers. For more information about the RPC Runtime Library, visit the following MSDN Library Web site.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could cause the affected system to stop responding or potentially read portions of active memory.

Who could exploit the vulnerability?
Any anonymous user who can deliver a series of specially crafted messages to the affected system could attempt to exploit this vulnerability. By default, this ability is enabled on the affected systems. Therefore, any user who can establish a connection to an affected system could attempt to exploit this vulnerability.

How could an attacker exploit the vulnerability?
An attacker could exploit this vulnerability by creating a series of specially crafted network messages and sending the messages to an affected system.

An attacker could also access the affected component through another vector. For example, an attacker could log on to the system interactively or by using another program that passes parameters to the vulnerable component (locally or remotely).

Could the vulnerability be exploited over the Internet?
Yes. An attacker may be able 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 on how you can help protect your PC. IT Professionals can visit the Security Center Web site.

What does the update do?
The update removes the vulnerability by modifying the way that RPC Runtime Library validates the length of a message before it passes the message to the allocated buffer.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible disclosure. Microsoft had not received any information indicating that this vulnerability had been publicly disclosed when this security bulletin was originally issued.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
No. Microsoft had not received any information indicating 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.

How does this vulnerability relate to the RPC vulnerabilities that are addressed by MS04-012?
Both security bulletins are related to RPC components. However, this update addresses a new vulnerability that was not addressed as part of MS04-012. MS04-012 helps protect against the vulnerabilities that are discussed in that bulletin, but does not address this new vulnerability. This update does not replace MS04-012. You must install this update and the update provided as part of the MS04-012 security bulletin to help protect your system against the vulnerabilities addressed by each security bulletin.

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Security Update Information

Installation Platforms and Prerequisites:

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

Windows NT 4.0 (all versions)

Prerequisites
This security update requires Windows NT Server 4.0 Service Pack 6a (SP6a) or Windows NT Server 4.0 Terminal Server Edition Service Pack 6 (SP6).

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

For more information about obtaining the latest service pack, see Microsoft Knowledge Base Article 152734.

Installation Information

This security update supports the following setup switches:

/y: Perform removal (only with /m or /q )

/f: Force programs to quit during the shutdown process

/n: Do not create an Uninstall folder

/z: Do not restart when the update completes

/q: Use Quiet or Unattended mode with no user interface (this switch is a superset of /m )

/m: Use Unattended mode with a user interface

/l: List the installed hotfixes

/x: Extract the files without running Setup

Note You can combine these switches into one command. For more information about the supported installation switches, see Microsoft Knowledge Base Article 262841.

Deployment Information

To install the security update without any user intervention, use the following command at a command prompt for Windows NT Server 4.0:

Windowsnt4server-kb873350-x86-enu /q

For Windows NT Server 4.0 Terminal Server Edition:

Windowsnt4terminalserver-kb873350-x86-enu /q

To install the security update without forcing the system to restart, use the following command at a command prompt for Windows NT Server 4.0:

Windowsnt4server-kb873350-x86-enu /z

For Windows NT Server 4.0 Terminal Server Edition:

Windowsnt4terminalserver-kb873350-x86-enu /z

Restart Requirement

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

Removal Information

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

System administrators can also use the Hotfix.exe utility to remove this security update. The Hotfix.exe utility is located in the %Windir%\$NTUninstallKB873350$ folder. The Hotfix.exe utility supports the following setup switches:

/y: Perform removal (only with the /m or /q switch)

/f: Force programs to quit during the shutdown process

/n: Do not create an Uninstall folder

/z: Do not restart when the installation is complete

/q: Use Quiet or Unattended mode with no user interface (this switch is a superset of the /m switch)

/m: Use Unattended mode with a user interface

/l: List the installed hotfixes

File Information

The English version of this update has the file attributes (or later) 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.

Note Date, time, file name, or size information could change during installation. See the Verifying Update Installation section for details about how to verify an installation.

Windows NT Server 4.0:

Date         Time   Version        Size     File name
------------------------------------------------------
25-Feb-2004  15:53  4.0.1381.7263  701,200  Ole32.dll        
17-Aug-2004  10:38  4.0.1381.7299  345,872  Rpcrt4.dll       
25-Feb-2004  15:53  4.0.1381.7263  122,128  Rpcss.exe

Windows NT Server 4.0 Terminal Server Edition:

Date         Time   Version         Size     File name
-------------------------------------------------------
25-Feb-2004  15:52  4.0.1381.33562  701,200  Ole32.dll        
21-Jul-2004  12:33  4.0.1381.33578  345,360  Rpcrt4.dll       
25-Feb-2004  15:52  4.0.1381.33562  124,176  Rpcss.exe

Verifying Update Installation

•

Microsoft Baseline Security Analyzer

To verify that a security update is installed on an affected system, you may be able to use the Microsoft Baseline Security Analyzer (MBSA) tool. This tool 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 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 the update installation. 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\Windows NT\CurrentVersion\Hotfix\KB873350\File 1

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 873350 security update into the Windows installation source files.

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Acknowledgments

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

•	BindView for reporting the RPC Runtime Library Vulnerability (CAN-2004-0569).

Obtaining Other Security Updates:

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

•	Security updates are available from the Microsoft Download Center. You can find them most easily by doing a keyword search for "security_patch."
•	Updates for consumer platforms are available from the Windows Update Web site.

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:

•	The Microsoft TechNet Security Web site provides additional information about security in Microsoft products.
•	Microsoft Software Update Services
•	Microsoft Baseline Security Analyzer (MBSA)
•	Windows Update
•	Windows Update Catalog: For more information about the Windows Update Catalog, see Microsoft Knowledge Base Article 323166.
•	Office Update

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 to 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, see 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 and the Microsoft Office Detection 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, see 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 (October 12, 2004): Bulletin published

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