Microsoft KB Archive/216803

= IIS Hidden Static Files Return HTTP 404 or Access Denied Errors =

Article ID: 216803

Article Last Modified on 12/3/2007

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APPLIES TO


 * Microsoft Internet Information Server 3.0
 * Microsoft Internet Information Server 4.0
 * Microsoft Internet Information Services 5.0
 * Microsoft Internet Information Services 6.0

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This article was previously published under Q216803



We strongly recommend that all users upgrade to Microsoft Internet Information Services (IIS) version 6.0 running on Microsoft Windows Server 2003. IIS 6.0 significantly increases Web infrastructure security. For more information about IIS security-related topics, visit the following Microsoft Web site:

http://www.microsoft.com/technet/security/prodtech/IIS.mspx



SYMPTOMS
Static files that have the hidden attribute set may return an HTTP 404 or an Access Denied error when browsed, while dynamic files can still be browsed.



CAUSE
This behavior is by design.



RESOLUTION
Configuring access control for all Web files should always be implemented through NTFS permissions.



MORE INFORMATION
Dynamic files such as Active Server Pages (ASP) or Server-Side Includes (SSI) are implemented through script-mapped ISAPI extensions, in this case the Asp.dll and Ssiinc.dll files respectively. These extensions preprocess the executable code in the files being requested and can therefore read hidden files and return the expected HTML output to a client. Direct Web browsing of hidden static files results in a "File not Found" or an "Access Denied" error message.

Additional query words: iis 5 iis5 iis 6 iis 6.0 iis 6

Keywords: kbhttp404 kbprod2web KB216803

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