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Article ID: 254142 - Last Review: November 21, 2006 - Revision: 6.2

MS00-023: 100% CPU Usage Occurs When You Send a Large Escape Sequence

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This article was previously published under Q254142

SYMPTOMS

When you send a large escape sequence to a computer running Internet Information Server 4.0 or Internet Information Services 5.0, the computer may use 100 percent CPU while it is processing the request. During this time, the server may not respond to other requests.

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CAUSE

This problem occurs because the Str::unescape function parses the escape characters in the request string by processing one character at a time, shifting the data over each time, and then starting again from the beginning of the request string. This takes a considerable amount of CPU usage, and can cause the server to stop processing other requests.

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RESOLUTION

Internet Information Services 5.0 (Windows 2000)

To resolve this problem, obtain the latest service pack for Windows 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

260910 (http://support.microsoft.com/kb/260910/EN-US/ ) How to Obtain the Latest Windows 2000 Service Pack

The following files are available for download from the Microsoft Download Center:

US English:

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Download Q254142_w2k_sp1_x86_en.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=en&familyId=EEA91314-99A1-4393-AABC-DAB10DFABD3D)

Arabic:

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Download Q254142_w2k_sp1_x86_ar.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=ar&familyId=EEA91314-99A1-4393-AABC-DAB10DFABD3D)

Chinese (Simplified):

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Download Q254142_w2k_sp1_x86_cn.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=zh-cn&familyId=EEA91314-99A1-4393-AABC-DAB10DFABD3D)

Chinese (Traditional):

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Download Q254142_w2k_sp1_x86_tw.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=zh-tw&familyId=EEA91314-99A1-4393-AABC-DAB10DFABD3D)

German:

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Download Q254142_w2k_sp1_x86_de.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=de&familyId=EEA91314-99A1-4393-AABC-DAB10DFABD3D)

Hebrew:

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Download Q254142_w2k_sp1_x86_he.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=he&familyId=EEA91314-99A1-4393-AABC-DAB10DFABD3D)

Japanese:

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Download Q254142_w2k_sp1_x86_ja.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=ja&familyId=EEA91314-99A1-4393-AABC-DAB10DFABD3D)

Korean:

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Download Q254142_w2k_sp1_x86_ko.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=ko&familyId=EEA91314-99A1-4393-AABC-DAB10DFABD3D)

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591 (http://support.microsoft.com/kb/119591/EN-US/ ) 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 security-enhanced servers that help to prevent any unauthorized changes to the file.

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Internet Information Server 4.0

The following files are available for download from the Microsoft Download Center:
US English:

x86:

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Download Escseq4i.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=en&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Alpha:

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Download Escseq4a.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=en&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Chinese (Simplified):

x86:

Collapse this imageExpand this image

Download Escseq4i.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=zh-cn&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Alpha:

Collapse this imageExpand this image

Download Escseq4a.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=zh-cn&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Chinese (Traditional):

x86:

Collapse this imageExpand this image

Download Escseq4i.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=zh-tw&FamilyID=75F808BE-31DA-4B17-8071-C0A6A0284193)

Alpha:

Collapse this imageExpand this image

Download Escseq4a.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=zh-tw&FamilyID=75F808BE-31DA-4B17-8071-C0A6A0284193)

Dutch:

x86:

Collapse this imageExpand this image

Download Escseq4i.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=nl&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Alpha:

Collapse this imageExpand this image

Download Escseq4a.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=nl&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

French:

x86:

Collapse this imageExpand this image

Download Escseq4i.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=fr&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Alpha:

Collapse this imageExpand this image

Download Escseq4a.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=fr&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

German:

x86:

Collapse this imageExpand this image

Download Escseq4i.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=de&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Alpha:

Collapse this imageExpand this image

Download Escseq4a.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=de&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Japanese:

x86:

Collapse this imageExpand this image

Download Escseq4i.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=ja&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Alpha:

Collapse this imageExpand this image

Download Escseq4a.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=ja&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Korean:

x86:

Collapse this imageExpand this image

Download Escseq4i.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=ko&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Alpha:

Collapse this imageExpand this image

Download Escseq4a.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=ko&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Portuguese (Brazil):

x86:

Collapse this imageExpand this image

Download Escseq4i.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=pt-br&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Alpha:

Collapse this imageExpand this image

Download Escseq4a.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=pt-br&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Spanish:

x86:

Collapse this imageExpand this image

Download Escseq4i.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=es&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Alpha:

Collapse this imageExpand this image

Download Escseq4a.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=es&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Swedish:

x86:

Collapse this imageExpand this image

Download Escseq4i.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=sv&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

Alpha:

Collapse this imageExpand this image

Download Escseq4a.exe now (http://www.microsoft.com/downloads/details.aspx?displaylang=sv&familyId=75F808BE-31DA-4B17-8071-C0A6A0284193)

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591 (http://support.microsoft.com/kb/119591/EN-US/ ) How to Obtain Microsoft Support Files from Online Services

   Date      Time       Version       Size     File name    Platform
   -----------------------------------------------------------------
   2-24-2000 8:15:06pm  4.2.740.1     185,760b Infocomm.dll x86
   2-24-2000 8:16:02pm  4.2.740.1     38,256b  Ssinc.dll    x86
   2-24-2000 8:16:10pm  4.2.740.1     25,360b  Sspifilt.dll x86
   2-24-2000 8:15:50pm  4.2.740.1     228,480b W3svc.dll    x86

   2-25-2000 12:15:19am 4.2.740.1     304,400b Infocomm.dll alpha
   2-25-2000 12:16:14am 4.2.740.1     60,176b  Ssinc.dll    alpha
   2-25-2000 12:16:20am 4.2.740.1     39,696b  Sspifilt.dll alpha
   2-25-2000 12:16:01am 4.2.740.1     383,760b W3svc.dll    alpha

Microsoft Windows NT Server version 4.0, Terminal Server Edition

To resolve this problem, obtain the Windows NT Server 4.0, Terminal Server Edition, Security Rollup Package (SRP). For additional information about the SRP, click the article number below to view the article in the Microsoft Knowledge Base:

317636 (http://support.microsoft.com/kb/317636/EN-US/ ) Windows NT Server 4.0, Terminal Server Edition, Security Rollup Package

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STATUS

Windows 2000

Microsoft has confirmed that this is a problem in Internet Information Services 5.0. This problem was first corrected in Windows 2000 Service Pack 1.

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Windows NT 4.0

Microsoft has confirmed that this is a problem in Internet Information Server 4.0.

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MORE INFORMATION

When you install this fix, the Str::unescape function traverses the request string only one time.

For additional information, please see the Microsoft Security Bulletin at the following Microsoft Web site:

http://www.microsoft.com/technet/security/Bulletin/MS00-023.mspx (http://www.microsoft.com/technet/security/Bulletin/MS00-023.mspx)

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