Article ID: 249599
Article Last Modified on 9/4/2007
APPLIES TO
- Microsoft Internet Information Server 4.0
- Microsoft Internet Information Services 5.0
This article was previously published under Q249599
SYMPTOMS
If a virtual directory on an Internet Information Server (IIS) computer is mapped to a Universal Naming Convention (UNC) share, and a request for a file in the directory contains one of several particular characters at the end of the request, the expected Internet Server Application Programming Interface (ISAPI) extension processing may not occur. This can result in the source code of the file being sent to the browser.
CAUSE
This problem can be caused by the use of a varying combination of special characters at the end of the clients request.
RESOLUTION
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 How to Obtain the Latest Windows 2000 Service Pack
This fix is also available individually. The following files are available for download from the Microsoft Download Center:
US English
![[GRAPHIC: Download]](/wiki/index.php?title=File:Download.gif){kind=small}
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Arabic
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Chinese (Simplified)
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Chinese (Traditional)
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Czech
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Danish
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Dutch
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Finnish
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French
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German
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Greek
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Hebrew
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Hungarian
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Italian
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Japanese
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Korean
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Norwegian
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Polish
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Portuguese (Brazil)
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Portuguese
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Swedish
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Turkish
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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 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.
Windows NT 4.0
The following files are available for download from the Microsoft Download Center:
US English
x86: Download Uncsec4i.exe now
Alpha: Download Uncsec4a.exe now
Dutch
x86: Download Uncsec4i.exe now
Alpha: Download Uncsec4a.exe now
French
x86: Download Uncsec4i.exe now
Alpha: Download Uncsec4a.exe now
German
x86: Download Uncsec4i.exe now
Alpha: Download Uncsec4a.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:
German x86 Symbols: Download Uncsec4is.exe now
German Alpha Symbols: Download Uncsec4as.exe now
Portuguese (Brazilian)
x86: Download Uncsec4i.exe now
Alpha: Download Uncsec4a.exe now
Spanish
x86: Download Uncsec4i.exe now
Alpha: Download Uncsec4a.exe now
Swedish
x86: Download Uncsec4i.exe now
Alpha: Download Uncsec4a.exe now
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 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.
The English version of this fix should have the following file attributes or later:
Date Time Version Size File name Platform
-------------------------------------------------------------
12/28/99 06:02p 4.2.736.1 185,248 Infocomm.dll x86
12/28/99 06:03p 4.2.736.1 38,256 Ssinc.dll x86
12/28/99 06:03p 4.2.736.1 25,360 Sspifilt.dll x86
12/28/99 06:03p 4.2.736.1 228,464 W3svc.dll x86
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
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.
Windows NT 4.0
Microsoft has confirmed that this is a problem in Internet Information Server 4.0.
MORE INFORMATION
There are significant restrictions that increase the difficulty of exploiting this vulnerability:
- By design, virtual directories hide the actual location of files. Under most circumstances, there is no way for an attacker to determine which files on a server actually reside on a UNC share.
- Many browsers "correct" requests that contain the trailing characters at issue here by either removing the characters or changing them.
- If recommended security practices are followed, ASP and other files that require server-side processing will not contain any sensitive information to compromise.
This fix eliminates the vulnerability by removing the trailing special characters if they are included in the request. This causes the appropriate scripting engine to process the file when the request is returned to the browser. If the request is improperly formatted, the request is denied, and then returned to the client as an invalid request.
For related information about this problem, please visit the following Microsoft Web site:
For additional security-related information about Microsoft products, please visit the following Microsoft Web site:
For additional information about how to install Windows 2000 and Windows 2000 hotfixes at the same time, click the article number below to view the article in the Microsoft Knowledge Base:
249149 Installing Microsoft Windows 2000 and Windows 2000 Hotfixes
Additional query words: tsesrp
Keywords: kbdownload kbbug kbfix kbgraphxlinkcritical kbsecurity kbhotfixserver kbqfe KB249599
