• Article

Security Bulletin

Microsoft Security Bulletin MS04-022 - Critical

Vulnerability in Task Scheduler Could Allow Code Execution (841873)

Published: July 13, 2004 | Updated: July 19, 2004

Version: 1.1

Issued: July 13, 2004
Updated: July 19, 2004
Version: 1.1

Summary

Who should read this document: Customers who use Microsoft® Windows®

Impact of Vulnerability: Remote Code Execution

Maximum Severity Rating: Critical

Recommendation: Customers should apply the update immediately.

Security Update Replacement: None

Caveats: Subsequent to the release of this bulletin, an additional work around was discovered which can prevent the possibility of an attack. For details, please view the "Workarounds" section of the bulletin under "Vulnerability Details".

Windows NT Workstation 4.0, Windows NT Server 4.0 and Windows NT 4.0 Terminal Server Edition are not affected by default. However if you have installed Internet Explorer 6.0 Service Pack 1 you will have the vulnerable component on your system.

Tested Software and Security Update Download Locations:

Affected Software:

  • Microsoft Windows 2000 Service Pack 2, Microsoft Windows 2000 Service Pack 3, Microsoft Windows 2000 Service Pack 4 - Download the update
  • Microsoft Windows XP and Microsoft Windows XP Service Pack 1 - Download the update
  • Microsoft Windows XP 64-Bit Edition Service Pack 1 - Download the update

Non-Affected Software:

  • Microsoft Windows Server™ 2003
  • Microsoft Windows Server 2003 64-Bit Edition
  • Microsoft Windows XP 64-Bit Edition Version 2003
  • Microsoft Windows NT® Workstation 4.0 Service Pack 6a
  • Microsoft Windows NT Server 4.0 Service Pack 6a
  • Microsoft Windows NT Server 4.0 Terminal Server Edition Service Pack 6
  • Microsoft Windows 98, Microsoft Windows 98 Second Edition (SE), and Microsoft Windows Millennium Edition (Me)

Tested Microsoft Windows Components:

Affected Components:

  • Internet Explorer 6 Service Pack 1 when installed on Windows NT 4.0 SP6a (Workstation, Server, or Terminal Server Edition) - Download the update

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.

General Information

Executive Summary

Executive Summary:

This update resolves a newly-discovered, privately reported vulnerability. A remote code execution vulnerability exists in the Task Scheduler because of an unchecked buffer. The vulnerability is documented in the Vulnerability Details section of this bulletin.

If a user is logged on with administrative privileges, an attacker who successfully exploited this vulnerability could take complete control of an affected system, including installing programs; viewing, changing, or deleting data; or creating new accounts with full privileges. However, user interaction is required to exploit this vulnerability. Users whose accounts are configured to have fewer privileges on the system would be at less risk than users who operate with administrative privileges.

We recommend that customers apply the update immediately.

Severity Ratings and Vulnerability Identifiers:

Vulnerability Identifiers Impact of Vulnerability Internet Explorer 6 Windows 2000 Windows XP
Task Scheduler Vulnerability - CAN-2004-0212 Remote Code Execution Critical Critical Critical

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.

How does the extended support for Windows 98, Windows 98 Second Edition, and Windows Millennium Edition affect the release of security updates for these operating systems?
Microsoft will only release security updates for critical security issues. Non-critical security issues are not offered during this support period. For more information about the Microsoft Support Lifecycle policies for these operating systems, visit the following Web site.

For more information about severity ratings, visit the following Web site.

Are Windows 98, Windows 98 Second Edition, or Windows Millennium Edition critically affected by any of the vulnerabilities that are addressed in this security bulletin?
No. None of these vulnerabilities are critical in severity on Windows 98, on Windows 98 Second Edition, or on Windows Millennium Edition, even with Internet Explorer 6 SP1 installed.

Is Windows NT 4.0 Service Pack 6a affected by the vulnerability that is addressed in this security bulletin?
By default, this operating system does not natively provide a version of the vulnerable component and is not affected. However, the vulnerable component is installed on this operating system when you install Internet Explorer 6. If you use this version of Internet Explorer on this operating system, you should install the provided security update for Internet Explorer 6.

I'm still using Microsoft Windows NT 4.0 Workstation Service Pack 6a or Windows 2000 Service Pack 2, but extended security update support ended on June 30, 2004. However, this bulletin has a security update for these operating system versions. Why is that?
Windows NT 4.0 Workstation Service Pack 6a and Windows 2000 Service Pack 2 have reached the end of their life cycles as previously documented, and Microsoft extended this support to June 30, 2004. However, the end-of-life for the extended support period occurred very recently. In this case, the majority of the steps that are required to address this vulnerability were completed before June 30, 2004. Therefore, we have decided to release security updates for these operating system versions as part of this security bulletin. We do not anticipate doing this for future vulnerabilities affecting these operating system versions, but we reserve the right to produce updates and to make these updates available when necessary.

It should be a priority for customers who have these operating system versions to migrate to supported versions to prevent potential exposure to future 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 these operating system versions, 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 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 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?
MBSA will determine if this update is required for Windows 2000 (all versions) and Windows XP (all versions). MBSA does not currently support the full detection of this update for the Windows NT 4.0 product (all versions). 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?
SMS uses MBSA for detection. SMS can help detect and deploy this security update for Windows 2000 (all versions) and Windows XP (all versions). This update is not detected by MBSA for the Windows NT 4.0 product (all versions). However, the file and registry key information that is available in this bulletin can be used to write specific file and registry key collection queries in SMS to detect vulnerable computers. For information about how to deploy updates not supported by MBSA with SMS, please review Knowledge Base article 867832. For information about SMS, visit the SMS Web site.

Vulnerability Details

Task Scheduler Vulnerability - CAN-2004-0212:

A remote code execution vulnerability exists in the Task Scheduler because of the way that it handles application name validation. There are many ways that a system could be vulnerable to this attack. An attacker who successfully exploited this vulnerability could take complete control of an affected system. However, user interaction is required to exploit this vulnerability.

Mitigating Factors for Task Scheduler Vulnerability - CAN-2004-0212:

  • 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. 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 site. An attack could only occur after they performed these actions.
  • An attacker who successfully exploited this vulnerability could gain the same privileges as the user. Users whose accounts are configured to have fewer privileges on the system would be at less risk than users who operate with administrative privileges.
  • Windows Server 2003 is not affected by this vulnerability. Windows NT 4.0 is not vulnerable unless Internet Explorer 6 is installed. Internet Explorer 6 is not affected when installed on other supported operating systems. Other versions Internet Explorer are not affected.

Workarounds for Task Scheduler Vulnerability - CAN-2004-0212:

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.

  • Do not open or save .job files that you receive from untrusted sources. This vulnerability could be exploited when a user views a .job file. Do not open files that use this file name extension.
  • Disable the dynamic icon handler for JobObject files by clearing the default value in the following registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Classes\JobObject\shellex\IconHandler
  1. Click Start, click Run, type "regedt32" (without the quotation marks), and then click OK.
  2. In Registry Editor, locate the following registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Classes\JobObject\shellex\IconHandler
  3. On the right windows pane you see a value of Default with Data of {DD2110F0-9EEF-11cf-8D8E-00AA0060F5BF}.
  4. Right click on Default and select Modify.
  5. Clear out the Value Data listed and click OK.

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.

Note We recommend backing up the registry before you edit it.

Impact of Workaround: Clearing the value of this key will prevent the possibility of attack by preventing the IconHandler from automatically parsing .job files. The files will no longer have an icon associated with them.

FAQ for Task Scheduler Vulnerability - CAN-2004-0212:

What is the scope of the vulnerability?
This is a remote code execution vulnerability. If a user is logged on with administrative privileges, an attacker who successfully exploited this vulnerability could take complete control of an affected system, including installing programs; viewing, changing, or deleting data; or creating new accounts with full privileges. Users whose accounts are configured to have fewer privileges on the system would be at less risk than users who operate with administrative privileges. However, user interaction is required to exploit this vulnerability.

What causes the vulnerability?
An unchecked buffer in the Task Scheduler component.

What is the Task Scheduler?
You can use Task Scheduler to schedule commands, programs, or scripts to run at specific times. A task is saved as a file that has a .job file name extension. This behavior makes it easier to move the task information from system to system. Administrators can create scheduled maintenance task files and put them where needed. For more information, see the Task Scheduler Web site.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could take complete control of an affected system, including installing programs; viewing, changing, or deleting data; or creating new accounts that have full privileges.

How could an attacker exploit this vulnerability?
There are many ways that a system could be vulnerable to this attack. Here are some examples:

  • An attacker could host a malicious Web site that is designed to exploit this vulnerability through Internet Explorer and then persuade a user to view the Web site.
  • An attacker could add a specially crafted .job file to the local file system or to a network share and then persuade the user to view the folder by using Windows Explorer.
  • 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).

What systems are primarily at risk from the vulnerability?
Workstations and terminal servers are primarily at risk. Servers are only at risk if users who do not have sufficient administrative credentials are given the ability to log on to servers and to run programs. However, best practices strongly discourage allowing this.

Could the vulnerability be exploited over the Internet?
Yes. An attacker could attempt to exploit this vulnerability over 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 Center Web site.

What does the update do?
The update removes the vulnerability by modifying the way that Task Scheduler 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.

Security Update Information

Installation Platforms and Prerequisites:

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

Windows XP (all versions)

Note For Windows XP 64-Bit Edition Version 2003, this security update is the same as the Windows Server 2003 64-Bit Edition security update.

Prerequisites This security update requires the release version of Windows XP or Windows XP Service Pack 1 (SP1). For more information, see Microsoft Knowledge Base Article 322389.

Inclusion in Future Service Packs: The update for this issue will be included in Windows XP Service Pack 2.

Installation Information

This security update supports the following setup switches:

/help                 Displays the command line options

Setup Modes

/quiet            Quiet mode (no user interaction or display)

/passive            Unattended mode (progress bar only)

/uninstall          Uninstalls the package

Restart Options

/norestart          Do not restart when installation is complete

/forcerestart      Restart after installation

Special Options

/l                        Lists installed Windows hotfixes or update packages

/o                       Overwrite OEM files without prompting

/n                       Do not backup files needed for uninstall

/f                        Force other programs to close when the computer shuts down

/extract             Extracts files without starting setup

Note You can combine these switches into one command. For backward compatibility, the security update also supports the setup switches that the previous version of the setup utility uses. 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 XP:

Windowsxp-kb841873-x86-enu /passive /quiet

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

Windowsxp-kb841873-x86-enu /norestart

For more information about how to deploy this security update with Software Update Services, visit the Software Update Services Web site.

Restart Requirement

In some cases, this update does not require a restart. The installer stops the required services, applies the update, and then restarts the services. However, if the required services cannot be stopped for any reason or if required files are in use, this update will require a restart. If this occurs, a message appears that advises you to restart.

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 is located in the %Windir%\$NTUninstallKB841873$\Spuninst folder. The Spuninst.exe utility supports the following setup switches:

/?: Show the list of installation switches.

/u: Use unattended mode.

/f: Force other programs to quit when the computer shuts down.

/z: Do not restart when the installation is complete.

/q: Use Quiet mode (no user interaction).

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.

Windows XP Home Edition, Windows XP Professional, Windows XP Home Edition Service Pack 1, Windows XP Professional Service Pack 1, Windows XP Tablet PC Edition, and Windows XP Media Center Edition:

Date Time Version Size File name Folder
-------------------------------------------------------------------
08-Jun-2004 22:01 5.1.2600.105 48,640 Browser.dll RTMQFE
08-Jun-2004 22:01 5.1.2600.155 251,392 Mstask.dll RTMQFE
03-Jun-2004 22:54 5.1.2600.155 9,728 Mstinit.exe RTMQFE
08-Jun-2004 22:01 5.1.2600.122 301,568 Netapi32.dll RTMQFE
08-Jun-2004 22:01 5.1.2600.155 159,232 Schedsvc.dll RTMQFE
08-Jun-2004 22:02 5.1.2600.1564 260,096 Mstask.dll SP1QFE
08-Jun-2004 19:59 5.1.2600.1564 10,752 Mstinit.exe SP1QFE
08-Jun-2004 22:02 5.1.2600.1562 306,688 Netapi32.dll SP1QFE
08-Jun-2004 22:02 5.1.2600.1564 172,544 Schedsvc.dll SP1QFE
18-May-2004 03:46 5.1.2600.1555 593,408 Xpsp2res.dll SP1QFE

Windows XP 64-Bit Edition Service Pack 1:

Date Time Version Size File name Platform Folder
-------------------------------------------------------------------------------
05-Jun-2004 03:57 5.1.2600.1555 658,944 Mstask.dll SP1QFE
18-May-2004 02:34 5.1.2600.1555 25,600 Mstinit.exe SP1QFE
05-Jun-2004 03:57 5.1.2600.1562 905,728 Netapi32.dll SP1QFE
05-Jun-2004 03:57 5.1.2600.1555 576,000 Schedsvc.dll SP1QFE
18-May-2004 03:38 5.1.2600.1555 592,896 Xpsp2res.dll SP1QFE
05-Jun-2004 03:45 5.1.2600.1562 306,688 Wnetapi32.dll SP1QFE\WOW
18-May-2004 03:46 5.1.2600.1555 593,408 Wxpsp2res.dll SP1QFE\WOW

Notes The Windows XP versions of this security update are packaged as a dual-mode package, which contain files for both the original version of Windows XP and Windows XP Service Pack 1 (SP1). For more information about dual-mode packages, see Microsoft Knowledge Base Article 328848.

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, which 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 keys.

    For Windows XP Home Edition, Windows XP Professional, Windows XP Home Edition Service Pack 1, Windows XP Professional Service Pack 1, Windows XP 64-Bit Edition Service Pack 1, Windows XP Tablet PC Edition, and Windows XP Media Center Edition:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows XP\SP2\KB841873\Filelist

    For Windows XP 64-Bit Edition Version 2003:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows Server 2003\SP1\KB841873\Filelist

    Note These registry keys may not contain a complete list of installed files. Also, these registry keys may not be created correctly if an administrator or an OEM integrates or slipstreams the 841873 security update into the Windows installation source files.

Windows 2000 (all versions)

Prerequisites For Windows 2000, this security update requires Service Pack 2 (SP2), Service Pack 3 (SP3), or Service Pack 4 (SP4).

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 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 will be included in Windows 2000 Service Pack 5.

Installation Information

This security update supports the following setup switches:

/help                 Displays the command line options

Setup Modes

/quiet            Quiet mode (no user interaction or display)

/passive            Unattended mode (progress bar only)

/uninstall          Uninstalls the package

Restart Options

/norestart          Do not restart when installation is complete

/forcerestart      Restart after installation

Special Options

/l                        Lists installed Windows hotfixes or update packages

/o                       Overwrite OEM files without prompting

/n                       Do not backup files needed for uninstall

/f                        Force other programs to close when the computer shuts down

/extract             Extracts files without starting setup

Note You can combine these switches into one command. For backward compatibility, the security update also supports the setup switches that the previous version of the setup utility uses. 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 2000 Service Pack 2, Windows 2000 Service Pack 3, and Windows 2000 Service Pack 4:

Windows2000-kb841873-x86-enu /passive /quiet

To install the security update without forcing the system to restart, use the following command at a command prompt for Windows 2000 Service Pack 2, Windows 2000 Service Pack 3, and Windows 2000 Service Pack 4:

Windows2000-kb841873-x86-enu /norestart

For more information about how to deploy this security update with Software Update Services, visit the Software Update Services Web site.

Restart Requirement

In some cases, this update does not require a restart. The installer stops the required services, applies the update, and then restarts the services. However, if the required services cannot be stopped for any reason or if required files are in use, this update will require a restart. If this occurs, a message appears that advises you to restart.

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%\$NTUninstallKB841873$\Spuninst folder. The Spuninst.exe utility supports the following setup switches:

/?: Show the list of installation switches.

/u: Use unattended mode.

/f: Force other programs to quit when the computer shuts down.

/z: Do not restart when the installation is complete.

/q: Use Quiet mode (no user interaction).

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 verifying an installation.

Windows 2000 Service Pack 2, Windows 2000 Service Pack 3, and Windows 2000 Service Pack 4:

Date Time Version Size File name
----------------------------------------------------------
24-Mar-2004 02:17 5.0.2195.6866 69,904 Browser.dll
10-Jun-2004 16:58 4.71.2195.6920 216,848 Mstask.dll
05-Apr-2004 17:51 4.71.2195.6920 119,568 Mstask.exe
10-Jun-2004 16:58 5.0.2195.6949 309,008 Netapi32.dll

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, which 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\Updates\Windows 2000\SP5\KB841873\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 841873 security update into the Windows installation source files.

Internet Explorer 6 for Windows NT 4.0 SP6a

Prerequisites

To install the Internet Explorer 6 version of this update, you must be running one of the following versions of Windows:

  • Microsoft Windows NT® Workstation 4.0 Service Pack 6a
  • Microsoft Windows NT Server 4.0 Service Pack 6a
  • Microsoft Windows NT Server 4.0 Terminal Server Edition, Service Pack 6

Note Versions of Windows and versions of Internet Explorer that are not listed in this article are no longer supported or not affected. We recommend that you upgrade to a supported version of Windows and of Internet Explorer, and then apply the appropriate update.

For more information about support lifecycles for Windows components, see the following Microsoft Support Lifecycle Web site.

For more information about how to obtain the latest service pack for Internet Explorer 6, see Microsoft Knowledge Base Article 328548.

Installation Information

The security update supports the following setup switches:

/Q Specifies quiet mode, or suppresses prompts, when files are being extracted.

/Q:U Specifies user-quiet mode, which presents some dialog boxes to the user.

/Q:A Specifies administrator-quiet mode, which does not present any dialog boxes to the user.

/T: <full path> Specifies the target folder for extracting files.

/C Extracts the files without installing them. If /T: path is not specified, you are prompted for a target folder.

/C: <Cmd> Override Install Command defined by author. Specifies the path and name of the Setup .inf or .exe file.

/R:N Never restarts the computer after installation.

/R:I Prompts the user to restart the computer if a restart is required, except when used with /Q:A.

/R:A Always restarts the computer after installation.

/R:S Restarts the computer after installation without prompting the user.

/N:V No version checking - Install the program over any previous version.

Note These switches do not necessarily work with all updates. If a switch is not available then that functionality is not necessary for the proper installation of the update. Also, the use of the /N:V switch is unsupported and may result in an unbootable system. If the installation is unsuccessful, you should consult your support professional to understand why it failed to install.

For additional information about the supported setup switches, see Microsoft Knowledge Base Article 197147.

Deployment Information

For example, to install the update without any user intervention and not force the system to restart, run the following command:

IE-KB841873-WindowsNT4sp6-x86-ENU.exe /q:a /r:n

For information about how to deploy this security update with Software Update Services, visit the Software Update Services Web site.

Restart Requirements

In some cases, you do not have to restart your system after you apply this update. However, if the required files are in use, you must restart your system after you apply this update. If this behavior occurs, a message is displayed that advises you to restart your system. You do not have to use an administrator logon after the system restarts for any version of this update.

Removal Information

To remove this update, use the Add or Remove Programs tool (or the Add/Remove Programs tool) in Control Panel. Click Internet Explorer Q841873, and then click Change/Remove (or click Add/Remove).

System administrators can use the Ieuninst.exe utility to remove this update. This security update installs the Ieuninst.exe utility in the %Windir% folder. This utility supports the following setup switches:

/?: Show the list of supported switches

/z: Do not restart when the installation is complete

/q: Use Quiet mode (no user interaction)

For example, to remove this update without any user intervention, use the following command:

c:\windows\ieuninst /q c:\windows\inf\q841873.inf

Note This command assumes that Windows is installed in the C:\Windows folder.

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.

Date Time Version Size File name
--------------------------------------------------------
27-May-2004 19:52 4.71.1979.1 223,504 Mstask.dll

Verifying Update Installation

  • 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\Active Setup\Installed Components\{bfb56e60-5895-496c-bd6b-459b97142e4c}

    Confirm that the IsInstalled DWORD value that has a data value of 1 appears in the registry key.

  • Program Version Verification

    Confirm that Q841873 is listed in the Update Versions field in the About Internet Explorer dialog box

Other Information

Acknowledgments

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

Obtaining Other Security Updates:

Updates for other security issues are available from 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 this security update with Software Update Services, visit the Software 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 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 (July 13, 2004): Bulletin published
  • V1.1 (July 19, 2004): Bulletin updated with an additional workaround.

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