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