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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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require 'rex/encoder/alpha2/unicode_mixed'
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class MetasploitModule < Msf::Encoder::Alphanum
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  Rank = ManualRanking
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  def initialize
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    super(
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      'Name' => 'Alpha2 Alphanumeric Unicode Mixedcase Encoder',
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      'Description' => %q{
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        Encodes payload as unicode-safe mixedcase text.  This encoder uses
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        SkyLined's Alpha2 encoding suite.
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      },
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      'Author' => [ 'pusscat', 'skylined' ],
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      'Arch' => ARCH_X86,
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      'License' => BSD_LICENSE,
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      'EncoderType' => Msf::Encoder::Type::AlphanumUnicodeMixed,
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      'Decoder' => {
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        'BlockSize' => 1
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      })
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    register_options(
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      [
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        OptString.new('BufferRegister', [true, 'The register that points to the encoded payload', 'ECX'])
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      ]
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    )
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  end
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  #
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  # Returns the decoder stub that is adjusted for the size of the buffer
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  # being encoded.
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  #
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  def decoder_stub(_state)
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    reg = datastore['BufferRegister']
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    offset = datastore['BufferOffset'].to_i || 0
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    if !reg
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      raise EncodingError, 'Need BufferRegister'
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    end
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    Rex::Encoder::Alpha2::UnicodeMixed.gen_decoder(reg, offset)
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  end
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  #
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  # Encodes a one byte block with the current index of the length of the
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  # payload.
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  #
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  def encode_block(state, block)
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    Rex::Encoder::Alpha2::UnicodeMixed.encode_byte(block.unpack1('C'), state.badchars)
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  end
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  #
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  # Tack on our terminator
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  #
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  def encode_end(state)
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    state.encoded += Rex::Encoder::Alpha2::UnicodeMixed.add_terminator
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  end
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  #
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  # Returns the unicode version of the supplied buffer.
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  #
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  def to_native(buffer)
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    Rex::Text.to_unicode(buffer)
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  end
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end
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