Chunked Encoding Request with No Data Causes IIS Memory Leak

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Article ID: 252693
This article was previously published under Q252693
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Symptoms

A repetitive attack using a specially malformed request may cause Internet Information Server (IIS) to use a large amount of memory, and eventually cause the service to fail. This problem can occur when the client uses the Transfer-Encoding: chunked header in its request.

Resolution

Windows NT 4.0

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 are experiencing this specific problem.

To resolve this problem, 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:
http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS
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.

The following files are available for download from the Microsoft Download Center:
US English:
x86:
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Download
Download Chkenc4i.exe now
Alpha:
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Download
Download Chkenc4a.exe now
Chinese (Simplified):
x86:
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Download
Download Chkenc4i.exe now
NOTE: Debug symbol files are required by an administrator to do both kernel and user mode debugging, providing a method to resolve global variables and function names in the loaded executable file. Click the file names below to download the symbol files:

US English:
x86:
Collapse this imageExpand this image
Download
Download Chkenc4is.exe now
Alpha:
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Download
Download Chkenc4as.exe now
Chinese (Simplified):
x86:
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Download
Download Chkenc4is.exe now
The English version of this fix should have the following file attributes or later:
   Date        Time        Version      Size       File name     Platform
   ----------------------------------------------------------------------
   1/28/2000   02:32:16p   4.2.739.1    185,760b   Infocomm.dll  x86
   1/28/2000   02:33:10p   4.2.739.1    38,256b    Ssinc.dll     x86
   1/28/2000   02:33:18p   4.2.739.1    25,360b    Sspifilt.dll  x86
   1/28/2000   02:32:58p   4.2.739.1    228,480b   W3svc.dll     x86

   1/28/2000   05:32:05p   4.2.739.1    304,400b   Infocomm.dll  Alpha
   1/28/2000   05:53:00p   4.2.739.1    60,176b    Ssinc.dll     Alpha
   1/28/2000   05:53:07p   4.2.739.1    39,696b    Sspifilt.dll  Alpha
   1/28/2000   05:32:49p   4.2.739.1    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 Windows NT Server 4.0, Terminal Server Edition, Security Rollup Package

Status

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

Properties

Article ID: 252693 - Last Review: November 2, 2013 - Revision: 5.0
Keywords: 
kbnosurvey kbarchive kbbug kbfix kbgraphxlinkcritical kbsecurity KB252693

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