122 lines
4.0 KiB
Ruby
122 lines
4.0 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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#
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# this sample shows how to compile an executable file from source
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# use --exe PE to compile a PE/ELF/MachO etc
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# use --cpu MIPS/--16/--be to change the CPU
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# the arg is a source file (c or asm) (some arch may not yet support C compiling)
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# defaults to encoding a shellcode, use --exe to override (or the scripts samples/{elf,pe}encode)
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# to compile a shellcode to a cstring, use --cstring
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#
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require 'metasm'
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require 'optparse'
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$opts ||= {}
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$opts = {
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:execlass => Metasm::Shellcode,
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:cpu => Metasm::Ia32.new,
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:exetype => :bin,
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:macros => {}
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}.merge($opts)
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OptionParser.new { |opt|
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opt.on('-o file', 'output filename') { |f| $opts[:outfilename] = f }
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opt.on('-f') { $opts[:overwrite_outfile] = true }
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opt.on('--c', 'parse source as a C file') { $opts[:srctype] = 'c' }
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opt.on('--asm', 'parse asm as an ASM file') { $opts[:srctype] = 'asm' }
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opt.on('--stdin', 'parse source on stdin') { ARGV << '-' }
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opt.on('-v', '-W', 'verbose') { $VERBOSE=true }
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opt.on('-d', 'debug') { $DEBUG=$VERBOSE=true }
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opt.on('-D var=val', 'define a preprocessor macro') { |v| v0, v1 = v.split('=', 2) ; $opts[:macros][v0] = v1 }
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opt.on('--cstring', 'encode output as a C string') { $opts[:to_string] = :c }
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opt.on('--jsstring', 'encode output as a js string') { $opts[:to_string] = :js }
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opt.on('--string', 'encode output as a string to stdout') { $opts[:to_string] = :inspect }
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opt.on('--varname name', 'the variable name for string output') { |v| $opts[:varname] = v }
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opt.on('-e class', '--exe class', 'use a specific ExeFormat class') { |c| $opts[:execlass] = Metasm.const_get(c) }
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opt.on('--cpu cpu', 'use a specific CPU class') { |c| $opts[:cpu] = Metasm.const_get(c).new }
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# must come after --cpu in commandline
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opt.on('--16', 'set cpu in 16bit mode') { $opts[:cpu].size = 16 }
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opt.on('--le', 'set cpu in little-endian mode') { $opts[:cpu].endianness = :little }
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opt.on('--be', 'set cpu in big-endian mode') { $opts[:cpu].endianness = :big }
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opt.on('--fno-pic', 'generate position-dependant code') { $opts[:cpu].generate_PIC = false }
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opt.on('--shared', 'generate shared library') { $opts[:exetype] = :lib }
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}.parse!
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src = $opts[:macros].map { |k, v| "#define #{k} #{v}\n" }.join
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if file = ARGV.shift
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$opts[:srctype] ||= 'c' if file =~ /\.c$/
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if file == '-'
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src << $stdin.read
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else
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src << File.read(file)
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end
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else
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src << DATA.read # the text after __END__ in this file
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end
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if $opts[:srctype] == 'c'
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exe = $opts[:execlass].compile_c($opts[:cpu], src, file)
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else
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exe = $opts[:execlass].assemble($opts[:cpu], src, file)
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end
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if $opts[:to_string]
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str = exe.encode_string
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$opts[:varname] ||= File.basename(file.to_s)[/^\w+/] || 'sc' # derive varname from filename
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case $opts[:to_string]
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when :inspect
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str = "#{$opts[:varname]} = #{str.inspect}"
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when :c
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str = ["unsigned char #{$opts[:varname]}[#{str.length}] = "] + str.scan(/.{1,19}/m).map { |l|
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'"' + l.unpack('C*').map { |c| '\\x%02x' % c }.join + '"'
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}
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str.last << ?;
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when :js
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str << 0 if str.length & 1 != 0
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str = ["#{$opts[:varname]} = "] + str.scan(/.{2,20}/m).map { |l|
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'"' + l.unpack($opts[:cpu].endianness == :little ? 'v*' : 'n*').map { |c| '%%u%04x' % c }.join + '"+'
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}
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str.last[-1] = ?;
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end
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if of = $opts[:outfilename]
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abort "Error: target file #{of.inspect} exists !" if File.exists? of and not $opts[:overwrite_outfile]
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File.open(of, 'w') { |fd| fd.puts str }
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puts "saved to file #{of.inspect}"
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else
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puts str
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end
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else
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of = $opts[:outfilename] ||= 'a.out'
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abort "Error: target file #{of.inspect} exists !" if File.exists? of and not $opts[:overwrite_outfile]
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exe.encode_file(of, $opts[:exetype])
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puts "saved to file #{of.inspect}"
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end
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__END__
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#include <asm/unistd.h>
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jmp getip
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gotip:
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mov eax, __NR_write
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mov ebx, 1
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pop ecx
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mov edx, strend-str
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int 80h
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mov eax, __NR_exit
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mov ebx, 1
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int 80h
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getip:
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call gotip
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str db "Hello, world!", 0xa
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strend:
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