The following is a Security Bulletin from the Microsoft Product Security
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Microsoft Security Bulletin (MS00-019)
Patch Available for "Virtualized UNC Share" Vulnerability
Originally Posted: March 30, 2000
Summary
Microsoft has released a patch that eliminates a security
vulnerability in Microsoft(r) Internet Information Server and
products based on it. Under certain fairly unusual conditions, the
vulnerability could cause a web server to send the source code of
.ASP and other files to a visiting user.
Frequently asked questions regarding this vulnerability and the patch
can be found at
http://www.microsoft.com/technet/security/bulletin/fq00-019.asp
Issue
If a virtual directory on an IIS server is mapped to a UNC share, and
a request for a file in the directory contains one of several
particular characters at the end, the expected ISAPI extension
processing may not occur. The result is that the source code of the
file would be sent to the browser.
There are significant restrictions that would increase the difficulty
of exploiting this vulnerability:
NOTE: Proxy Server, Site Server, Site Server Commerce Edition and
Microsoft Commercial Internet System run atop IIS. Customers using
these products should apply the patch appropriate for the version of
IIS they are running.
NOTE: Additional security patches are available at the Microsoft
Download Center.
Please see the following references for more information related to
this issue.
This is a fully supported patch. Information on contacting Microsoft
Technical Support is available at
http://support.microsoft.com/support/contact/default.asp.