92 lines
2.5 KiB
Ruby
92 lines
2.5 KiB
Ruby
#!/usr/bin/env ruby
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# This file is part of Metasm, the Ruby assembly manipulation suite
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# Copyright (C) 2006-2009 Yoann GUILLOT
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#
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# Licence is LGPL, see LICENCE in the top-level directory
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# modifies the standard ruby class String to add #decode and #encode methods
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# they will respectively disassemble binary data / assemble asm source
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# the default CPU is x86 32bits, change it using eg String.cpu = Metasm::MIPS.new(:big) (mips bigendian)
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#
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# it also defines the toplevel 'asm' method, that will start an interactive
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# assembler shell (type in assembly statements, they are shown assembled in binary escaped form)
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#
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# eg:
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# ruby metasm-shell
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# > nop ; nop
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# "\x90\x90"
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# > exit
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require 'metasm'
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class String
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@@cpu = Metasm::Ia32.new
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class << self
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def cpu() @@cpu end
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def cpu=(c)
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c = Metasm.const_get(c).new if c.kind_of? String
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@@cpu=c
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end
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end
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# encodes the current string as a Shellcode, returns the resulting EncodedData
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def encode_edata
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s = Metasm::Shellcode.assemble @@cpu, self
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s.encoded
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end
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# encodes the current string as a Shellcode, returns the resulting binary String
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# outputs warnings on unresolved relocations
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def encode
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ed = encode_edata
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if not ed.reloc.empty?
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puts 'W: encoded string has unresolved relocations: ' + ed.reloc.map { |o, r| r.target.inspect }.join(', ')
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end
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ed.fill
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ed.data
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end
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# decodes the current string as a Shellcode, with specified base address
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# returns the resulting Disassembler
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def decode_blocks(base_addr=0, eip=base_addr)
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sc = Metasm::Shellcode.decode(self, @@cpu)
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sc.base_addr = base_addr
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sc.disassemble(eip)
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end
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# decodes the current string as a Shellcode, with specified base address
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# returns the asm source equivallent
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def decode(base_addr=0, eip=base_addr)
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decode_blocks(base_addr, eip).to_s
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end
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end
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# get in interactive assembler mode
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def asm
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puts 'type "exit" or "quit" to quit', 'use ";" for newline', ''
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while (print "asm> " ; $stdout.flush ; l = gets)
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break if %w[quit exit].include? l.chomp
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if l.chomp == 'help'
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puts "Metasm assembly shell: type in opcodes to see their binary form",
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"You can use ';' to type multi-line stuff",
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"e.g. 'nop nop' will display \"\\x90\\x90\""
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next
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end
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begin
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data = l.gsub(';', "\n")
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next if data.strip.empty?
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data = data.encode
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puts '"' + data.unpack('C*').map { |c| '\\x%02x' % c }.join + '"'
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rescue Metasm::Exception => e
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puts "Error: #{e.class} #{e.message}"
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end
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end
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puts
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end
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if __FILE__ == $0
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asm
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end
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