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

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 ([email protected]) 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/