cmd.exe Unicode Buffer Overflow (SEH)

                                                # Exploit Title: cmd.exe Unicode Buffer Overflow (SEH)
# Date: 7/8/2010
# Author: bitform
# Software Link: N/A
# Version: N/A
# Tested on: Windows Server 2003 SP2 and Windows XP SP2
# CVE : none
 
1) Acknowledgements
 
Props to Dan Crowley (@dan_crowley) at Core Security Technologies
for doing the research on Windows File Pseudonyms and coming up
with the idea for this buffer overflow.
 
His presentation can be found here:
www.sourceconference.com/bos10pubs/windows%20file%20pseudonyms.pptx
 
2) Bug
 
The TYPE command in Windows is equivalent to cat in *nix. It simply
outputs the contents of a file to stdout. If you use TYPE in conjunction
with the device file CON, you can feed stdin into a file.
 
Example: TYPE CON > evil.txt
 
CON is also interpreted as a file so you can append an extension to
it. Supplying a overly large extension will overflow the structured
exception handler.
 
This buffer overflow is not exploitable since cmd.exe and it's DLLs
are all compiled with SafeSEH. Oh well. :D
 
3) Code
 
TYPE CON.<A * 626><B * 2><C * 2372>
 
Note: The two B's is where the SEH is overwritten.