Microsoft IIS Remote Denial of Service (DoS) .DLL Url exploit

[inge.henriksen () booleansoft com]

** Inge Henriksen Security Advisory - Full Disclosure Proof of Concept at http://ingehenriksen.blogspot.com/ **

Advisory Name: 
Microsoft IIS Remote Denial of Service (DoS) .DLL Url exploit

Release Date: 
16. Desember 2005

Vulnerable: 
Microsoft® Internet Information Server® V5.1

Not vulnerable: 
Microsoft® Internet Information Server® V5.0 
Microsoft® Internet Information Server® V6.0

Severity: 
High

Discovered by: 
Inge Henriksen (inge.henriksen () booleansoft com) http://ingehenriksen.blogspot.com/

Vendor Status: 
Notified 28. January 2005. No fix will be released until Microsoft® Windows® XP Service Pack 3 
(Rumored due late 2006).

Description:
I have found that by doing a malformed anonymous HTTP request one can remotely crash the IIS service 
process, inetinfo.exe, using just a simple tool like a web browser. The vulnerablity is only present 
in folders with Execute Permissions set to Scripts & Executables, examples of vulnerable virtual 
folders would be "<webroot>/_vti_bin" and the like. 

Suggested solution:
Block all incoming URL's containing  "~0", "~1", "~2", "~3", "~4", "~5", "~6", "~7", "~8", or "~9" 
(Ignore quotes).

Full Disclosure Proof of Concept at http://ingehenriksen.blogspot.com/