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#!/usr/bin/env ruby
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##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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#
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# This tool provides an easy way to see what opcodes are associated with
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# certain x86 instructions by making use of nasm if it is installed and
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# reachable through the PATH environment variable.
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#
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begin
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msfbase = __FILE__
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while File.symlink?(msfbase)
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  msfbase = File.expand_path(File.readlink(msfbase), File.dirname(msfbase))
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end
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$:.unshift(File.expand_path(File.join(File.dirname(msfbase), '..', '..', 'lib')))
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$:.unshift(ENV['MSF_LOCAL_LIB']) if ENV['MSF_LOCAL_LIB']
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require 'msfenv'
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require 'rex'
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require 'readline'
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# Check to make sure nasm is installed and reachable through the user's PATH.
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begin
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  Rex::Assembly::Nasm.check
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rescue RuntimeError
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  puts "#{$!}"
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  exit
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end
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bits = ARGV.length > 0 ? ARGV[0].to_i : 32
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if ! [16, 32, 64].include?(bits) then
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    puts "#{bits} bits not supported"
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    exit 1
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end
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# Start a pseudo shell and dispatch lines to be assembled and then
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# disassembled.
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history_file = File.join(Msf::Config.config_directory, 'nasm_history')
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shell = Rex::Ui::Text::PseudoShell.new("%bldnasm%clr", '>', history_file)
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shell.init_ui(Rex::Ui::Text::Input::Stdio.new, Rex::Ui::Text::Output::Stdio.new)
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shell.history_manager = Rex::Ui::Text::Shell::HistoryManager.new
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shell.run { |line|
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  line.gsub!(/(\r|\n)/, '')
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  line.gsub!(/\\n/, "\n")
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  break if (line =~ /^(exit|quit)/i)
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  begin
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    puts(Rex::Assembly::Nasm.disassemble(
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      Rex::Assembly::Nasm.assemble(line, bits), bits))
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  rescue RuntimeError
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    puts "Error: #{$!}"
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  end
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}
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rescue SignalException => e
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  puts("Aborted! #{e}")
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end
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