encoders

git-svn-id: file:///home/svn/incoming/trunk@2597 4d416f70-5f16-0410-b530-b9f4589650da

lib/rex/encoder/xor.rb

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+#!/usr/bin/ruby
+
+module Rex
+module Encoder
+
+class Xor
+
+	attr_accessor :raw, :encoded, :badchars, :opts, :key
+
+	# wrap that shit in a wanna be static class
+	def self.encode(*args)
+		self.new.encode(*args)
+	end
+
+	def encoder()
+		self.class::EncoderKlass
+	end
+
+	def encode(data, badchars, opts = { })
+		self.raw      = data
+		self.badchars = badchars
+		self.opts     = opts
+
+		self.encoded, self.key = encoder().find_key_and_encode(data, badchars)
+		return _prepend() + encoded + _append()
+	end
+
+	protected
+	def _prepend()
+		""
+	end
+
+	def _append()
+		""
+	end
+
+end
+
+end end

lib/rex/encoder/xor/dword.rb

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+#!/usr/bin/ruby
+
+require 'Rex/Encoder/Xor'
+require 'Rex/Encoding/Xor/DWord'
+
+class Rex::Encoder::Xor::DWord < Rex::Encoder::Xor
+	EncoderKlass = Rex::Encoding::Xor::DWord
+end

lib/rex/encoders/xor_dword.rb

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+#!/usr/bin/ruby
+
+require 'Rex/Arch/X86'
+require 'Rex/Encoder/Xor/DWord'
+
+module Rex
+module Encoders
+
+# spoon's smaller variable-length encoder (updated to use call $+4 by vlad902)
+
+class XorDWord < Rex::Encoder::Xor::DWord
+	module Backend
+		def _prepend
+			# set the counter to the rounded up number of dwords to decode
+			Rex::Arch::X86.set(
+			  Rex::Arch::X86::ECX,
+			  (encoded.length - 1 >> 2) + 1,
+			  badchars
+			) +
+			"\xe8\xff\xff\xff" +                # call $+4
+			"\xff\xc0" +                        # inc eax
+			"\x5e" +                            # pop esi
+			"\x81\x76\x0e" + key +              # xor_xor: xor [esi + 0x0e], $xorkey
+			"\x83\xee\xfc" +                    # sub esi, -4
+			"\xe2\xf4"                          # loop xor_xor
+		end
+	end
+
+	include Backend
+end
+
+end end