Microsoft Knowledge Base Article - Q324096
 

MS02-053: Request to SmartHTML Interpreter May Monopolize Web Server CPU Resources

The information in this article applies to:
  • FrontPage 2002 Server Extensions from Microsoft
  • FrontPage 2000 Server Extensions from Microsoft
  • Microsoft Windows XP Home Edition
  • Microsoft Windows XP Professional
  • Microsoft Windows 2000, 2000 SP1, 2000 SP2, 2000 SP3 Advanced Server
  • Microsoft Windows 2000, 2000 SP1, 2000 SP2, 2000 SP3 Professional
  • Microsoft Windows 2000, 2000 SP1, 2000 SP2, 2000 SP3 Server

SYMPTOMS

SmartHTML Interpreter (Shtml.dll) is part of FrontPage Server Extensions; it provides support for Web forms and other FrontPage-based dynamic content. The interpreter contains a flaw that occurs when it processes a request for a particular type of Web file if the request includes certain other characteristics. Such a request may cause the interpreter to consume most or all CPU availability until the Web service is restarted. An attacker might be able to use this vulnerability to conduct a denial-of-service attack against an affected Web server.

Mitigating Factors

  • The vulnerability does not provide any way to take any broader action on the server. It does not permit an attacker to add, delete, or modify data on the server.
  • The IIS Lockdown Tool, if it is used to configure a static Web server, turns off SmartHTML Interpreter. Servers on which this tool has been used cannot be affected by the vulnerability.
  • By default, FrontPage Server Extensions is installed on Microsoft Internet Information Server 4.0 and Microsoft Internet Information Services 5.0 and 5.1, but can be removed. Servers on which Internet Information Server or Internet Information Services has been removed cannot be affected by the vulnerability.

RESOLUTION

FrontPage 2002 Server Extensions from Microsoft

For additional information about the security update, click the article number below to view the article in the Microsoft Knowledge Base:
    Q329086 FP2002: FrontPage 2002 Server Extensions Security Update: September 25, 2002
The English-language version of this fix has the file attributes (or later) that are listed in the following table:
   Version      File name     
   ------------------------
   10.0.4219.0  Fp5awel.dll
Microsoft also recommends that you install the FrontPage 2002 Server Extensions Update that was released in January, 2002. For additional information about the update, click the article number below to view the article in the Microsoft Knowledge Base:
    Q317296 Overview of the FrontPage 2002 Server Extension Update: January 28, 2002
back to the top

FrontPage 2000 Server Extensions from Microsoft

For additional information about the security update, click the article number below to view the article in the Microsoft Knowledge Base:
    Q329085 FP2000: FrontPage 2000 Server Extensions Security Update: September 25, 2002
The English-language version of this fix has the file attributes (or later) that are listed in the following table:
   Version      File name     
   ------------------------
   4.0.2.6426   Fp4awel.dll
back to the top

Windows XP

A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that you determine are at risk of attack. Evaluate your computer's physical accessibility, network and Internet connectivity, and other factors to determine the degree of risk to your computer. See the associated Microsoft Security Bulletin to help determine the degree of risk. This fix may receive additional testing. If your computer is sufficiently at risk, Microsoft recommends that you apply this fix now. Otherwise, wait for the next Windows XP that contains this fix.

To resolve this problem immediately, download the fix by following the instructions later in this article or contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site: NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Download Information

The following files are available for download from the Microsoft Download Center:
Release Date: September 25, 2002

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:
    Q119591 How to Obtain Microsoft Support Files from Online Services
Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on secure servers that prevent any unauthorized changes to the file.

Installation Options

You must restart your computer after you apply this update. This update supports the following Setup switches:
  • -?: Display the list of installation switches.
  • -u: Unattended mode.
  • -f: Force other programs to quit when the computer shuts down.
  • -n: Do not back up files for removal.
  • -o: Overwrite OEM files without prompting.
  • -z: Do not restart when installation is complete.
  • -q: Quiet mode (no user interaction).
  • -l: List installed hotfixes.
  • -x Extracts the files without running Setup.
For example, the following command line installs the update without any user intervention and then does not force the computer to restart:
    Q324096_wxp_sp1_x86_enu -u -q -z
WARNING: Your computer is vulnerable until you restart it.

File Information

The English version of this fix 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
   ------------------------------------------------------
   22-Jun-2002 10:37PM  10.0.4219.0  1382984  Fp5awel.dll
NOTE: Because of file dependencies, this update may contain additional files. back to the top

Windows 2000

A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that you determine are at risk of attack. Evaluate your computer's physical accessibility, network and Internet connectivity, and other factors to determine the degree of risk to your computer. See the associated Microsoft Security Bulletin to help determine the degree of risk. This fix may receive additional testing. If your computer is sufficiently at risk, Microsoft recommends that you apply this fix now. Otherwise, wait for the next Windows 2000 that contains this fix.

To resolve this problem immediately, download the fix by following the instructions later in this article or contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site: NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Download Information

The following file is available for download from the Microsoft Download Center:
Release Date: September 25, 2002

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:
    Q119591 How to Obtain Microsoft Support Files from Online Services
Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on secure servers that prevent any unauthorized changes to the file.

Installation Options

You must restart your computer after you apply this update. This update supports the following Setup switches:
  • -?: Display the list of installation switches.
  • -u: Unattended mode.
  • -f: Force other programs to quit when the computer shuts down.
  • -n: Do not back up files for removal.
  • -o: Overwrite OEM files without prompting.
  • -z: Do not restart when installation is complete.
  • -q: Quiet mode (no user interaction).
  • -l: List installed hotfixes.
  • -x Extracts the files without running Setup.
For example, the following command line installs the update without any user intervention and then does not force the computer to restart:
    q318138_w2k_sp3_x86_en /q /m /z
WARNING: Your computer is vulnerable until you restart it.

File Information

The English version of this fix 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 and path
    ------------------------------------------------------------------------
    27-Apr-2002  12:34PM  4.0.2.6426   872557   ???\fp4awel.dll
NOTE: Because of file dependencies, this update may contain additional files. This update requires Windows 2000 Service Pack 2 (SP2) or Service Pack 1 (SP1). back to the top

STATUS

Microsoft has confirmed that this problem may cause a degree of security vulnerability in the Microsoft products that are listed at the beginning of this article.

MORE INFORMATION

For more information about this vulnerability, see the following Microsoft Corporation.