Microsoft Security Bulletin (MS00-057)
Patch Available for "File Permission Canonicalization" Vulnerability
Originally posted: August 10, 2000
Microsoft has released a patch that eliminates a security
vulnerability in Microsoft(r) Internet Information Server. Under very
restricted conditions, the vulnerability could allow a malicious user
to gain additional permissions to certain types of files hosted on a
web server.
Frequently asked questions regarding this vulnerability and the patch
can be found at
http://www.microsoft.com/technet/security/bulletin/fq00-057.asp
A canonicalization error can, under certain conditions, cause IIS 4.0
or 5.0 to apply incorrect permissions to certain types of files. If
an affected file residing in a folder with restrictive permissions
were requested via a particular type of malformed URL, the
permissions actually used would be those of a folder in the file's
parentage chain, but not those of the folder the file actually
resides in. If the ancestor folder's permissions were more permissive
than those of the correct folder, the malicious user would gain
additional privileges to the affected file.
The vulnerability is subject to several significant restrictions:
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
Product Support Services is available at
http://support.microsoft.com/support/contact/default.asp.
Microsoft thanks Burt Abreu & SЬren Skov of VBExplorer.com for
reporting this issue to us and working with us to protect customers.
August 10, 2000: Bulletin Created.
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Last Updated August 10, 2000
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