Module: Msf::Exploit::PDF_Parse

Defined in:
lib/msf/core/exploit/pdf_parse.rb

Instance Method Summary collapse

Instance Method Details

#initialize(info = {}) ⇒ Object 



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# File 'lib/msf/core/exploit/pdf_parse.rb', line 12

def initialize(info = {})
  super

  register_options(
    [
      OptString.new('FILENAME', [ true, 'The file name.', 'some.pdf']),
    ], Msf::Exploit::PDF_Parse
  )

end

#object_locate(xref_trailer, obj_name) ⇒ Object 



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# File 'lib/msf/core/exploit/pdf_parse.rb', line 65

def object_locate(xref_trailer,obj_name)

  found = false
  match = obj_name.match(/(\d+) (\d+)/)
  obj = match[1]
  gen = match[2]

  xrefs_end = xref_trailer.index(/trailer/) - 1
  xrefs = xref_trailer[0..xrefs_end]

  if gen.to_i != 0

  else
    len = xrefs.length
    match = xrefs.match(/xref\r?\n?(\d+) (\d+)\r?\n?/m)
    offset = 0


    while offset < len

      if match
        start_obj = match[1]
        num_obj = match[2]
        offset = match.end(0)
      else
        break
      end

      if start_obj.to_i > obj.to_i
        jump = num_obj.to_i * 20
        offset += jump
      else
        if obj.to_i <= ( start_obj.to_i + num_obj.to_i - 1)

          jump = (obj.to_i - start_obj.to_i) * 20
          offset += jump
          found = true
          break
        else
          jump = num_obj.to_i * 20
          offset += jump
        end
      end

      xrefs.index(/(\d+) (\d+)\r?\n?/m,offset)
      match = Regexp.last_match
    end


  end

  if found
    offset_end = offset + 11
    return xrefs[offset..offset_end].to_i
  else
    return nil
  end

end

#parse_object(xref_trailers, obj_name, stream) ⇒ Object 



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# File 'lib/msf/core/exploit/pdf_parse.rb', line 125

def parse_object(xref_trailers,obj_name,stream)

  for xrefs in xref_trailers
    offset = object_locate(xrefs,obj_name)
    if offset
      break
    end
  end


  if offset
    stream.index(/endobj/,offset)
    object_end = Regexp.last_match.end(0)
    return stream[offset..object_end]
  else
    return nil
  end
end

#parse_pdf(stream) ⇒ Object 



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# File 'lib/msf/core/exploit/pdf_parse.rb', line 204

def parse_pdf(stream)

  xref_array = Array.new()

  startxrefs = Array.new()
  startxref_offsets = Hash.new()

  xref_trailers = Array.new()
  xref_trailer = Hash.new()

  trailers = Array.new()
  trailer = Hash.new()

  len = stream.length
  n = 0
  while n < len
    obj = stream.index(/startxref\r?\n?/m,n)
    if obj != nil
      n = Regexp.last_match.end(0)
      stream.index(/\d+/,n)
      startxref_offsets["#{Regexp.last_match}"] = "#{obj}"
      startxrefs.push("#{Regexp.last_match}")
    else
      break
    end
  end

  xref_trailer = xref_trailer_parse(startxrefs.last.to_i,stream)
  xref_trailers.push(xref_trailer)


  trailer = trailer_parse(xref_trailer)
  trailers.push(trailer)

  root_obj = trailers[0].fetch("Root")

  while trailer["Prev"]
    xref_trailer = xref_trailer_parse(trailer.fetch("Prev").to_i,stream)
    xref_trailers.push(xref_trailer)


    trailer = trailer_parse(xref_trailer)
    trailers.each {|check| if check.fetch("Prev") == trailer["Prev"] then trailer.delete("Prev") end}
    if trailer.has_key?("Prev")
      trailers.push(trailer)
    end
  end

  return xref_trailers, trailers, startxrefs, root_obj
end

#read_pdf ⇒ Object 



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# File 'lib/msf/core/exploit/pdf_parse.rb', line 23

def read_pdf()
  stream = File.binread("#{datastore['INFILENAME']}")
  return stream
end

#trailer_parse(xref_trailer) ⇒ Object 



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# File 'lib/msf/core/exploit/pdf_parse.rb', line 35

def trailer_parse(xref_trailer)
  trailer = Hash.new()

  if match = xref_trailer.match(/Size (\d+)/m)
    trailer['Size'] = match[1]
  end

  if match = xref_trailer.match(/Root (\d+ \d)/m)
    trailer["Root"] = match[1]
  end

  if match = xref_trailer.match(/Info (\d+ \d)/m)
    trailer["Info"] = match[1]
  end

  if match = xref_trailer.match(/ID(\[.+\])/m)
    trailer["ID"] = match[1]
  end

  if match = xref_trailer.match(/Prev (\d+)/m)
    trailer["Prev"] = match[1]
  end

  if match = xref_trailer.match(/XRefStm (\d+)/m)
    trailer["XRefStm"] = match[1]
  end

  return trailer
end

#xref_create(stream, offset, num_obj) ⇒ Object 



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# File 'lib/msf/core/exploit/pdf_parse.rb', line 144

def xref_create(stream,offset,num_obj)


  xref = Array.new()
  object = String.new()

  case
    when num_obj.to_s == "1"

      obj = stream.index(/(\d+) \d obj/,offset)
      if obj
        num = obj.to_s
        dif = 10 - num.length
        out = String.new
        while dif > 0
          out << "0"
          dif -= 1
        end
        out << num
        xref.push("#{out}")
        object = "#{Regexp.last_match(1)}"
      end

    when num_obj.to_s == "*"

      len = stream.length
      n = offset
      while n < len
        obj = stream.index(/(\d+) \d obj/,n)
        if obj != nil
          num = obj.to_s
          dif = 10 - num.length
          out = String.new
          while dif > 0
            out << "0"
            dif -= 1
          end
          out << num
          xref.push("#{out}")
          n = Regexp.last_match.end(0)

          if object.empty?
            object = "#{Regexp.last_match(1)}"
          end
        else
          break
        end
      end



  end

  output = String.new()
  output << "#{object} #{xref.length}\r\n"
  xref.each {|xref_| output << "#{xref_} 00000 n\r\n"}

  return output
end

#xref_trailer_parse(offset, stream) ⇒ Object 



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# File 'lib/msf/core/exploit/pdf_parse.rb', line 28

def xref_trailer_parse(offset, stream)

  a = offset
  b = stream.index(/>>/,a) + 2
  return stream[a..b]
end