James Lee
a127213a70
git-svn-id: file:///home/svn/framework3/trunk@7052 4d416f70-5f16-0410-b530-b9f4589650da
51 lines
1.3 KiB
Ruby
51 lines
1.3 KiB
Ruby
require 'msf/core'
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###
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#
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# This class provides basic XOR encoding of buffers.
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#
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###
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class Msf::Encoder::Xor < Msf::Encoder
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#
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# Encodes a block using the XOR encoder from the Rex library.
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#
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def encode_block(state, block)
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encoder = case state.decoder_key_size
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when Rex::Encoding::Xor::Qword.keysize then Rex::Encoding::Xor::Qword
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when Rex::Encoding::Xor::Dword.keysize then Rex::Encoding::Xor::Dword
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when Rex::Encoding::Xor::Word.keysize then Rex::Encoding::Xor::Word
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when Rex::Encoding::Xor::Byte.keysize then Rex::Encoding::Xor::Byte
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else Rex::Encoding::Xor::Dword
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end
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encoder.encode(block, [ state.key ].pack(state.decoder_key_pack))[0]
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end
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#
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# Finds keys that are incompatible with the supplied bad character list.
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#
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def find_bad_keys(buf, badchars)
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bad_keys = Array.new(decoder_key_size) { Hash.new }
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byte_idx = 0
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# Scan through all the badchars and build out the bad_keys array
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# based on the XOR'd combinations that can occur at certain bytes
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# to produce bad characters
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buf.each_byte { |byte|
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badchars.each_byte { |badchar|
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bad_keys[byte_idx % decoder_key_size][byte ^ badchar] = true
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}
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byte_idx += 1
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}
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badchars.each_byte { |badchar|
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0.upto(decoder_key_size-1) { |i|
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bad_keys[i][badchar] = true
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}
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}
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return bad_keys
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end
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end
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