metasploit-framework/modules/encoders/x86/nonupper.rb

71 lines
2.0 KiB
Ruby

##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
require 'msf/core'
require 'rex/encoder/nonupper'
class Metasploit < Msf::Encoder::NonUpper
Rank = LowRanking
def initialize
super(
'Name' => "Non-Upper Encoder",
'Description' => %q{
Encodes payloads as non-alpha based bytes. This allows
payloads to bypass tolower() calls, but will fail isalpha().
Table based design from Russel Sanford.
},
'Author' => [ 'pusscat'],
'Arch' => ARCH_X86,
'License' => BSD_LICENSE,
'EncoderType' => Msf::Encoder::Type::NonUpper,
'Decoder' =>
{
'BlockSize' => 1,
})
end
#
# Returns the decoder stub that is adjusted for the size of the buffer
# being encoded.
#
def decoder_stub(state)
state.key = ""
state.decoder_key_size = 0
Rex::Encoder::NonUpper::gen_decoder()
end
#
# Encodes a one byte block with the current index of the length of the
# payload.
#
def encode_block(state, block)
begin
newchar, state.key, state.decoder_key_size =
Rex::Encoder::NonUpper::encode_byte(datastore['BadChars'], block.unpack('C')[0], state.key, state.decoder_key_size)
rescue RuntimeError => e
# This is a bandaid to deal with the fact that, since it's in
# the Rex namespace, the encoder itself doesn't have access to the
# Msf exception classes. Turn it into an actual EncodingError
# exception so the encoder doesn't look broken when it just fails
# to encode.
raise BadcharError if e.message == "BadChar"
end
return newchar
end
#
# Fix stuff, and add the table :)
#
def encode_end(state)
state.encoded.gsub!(/A/, state.decoder_key_size.chr)
state.encoded.gsub!(/B/, (state.decoder_key_size+5).chr)
state.encoded[0x24, 0] = state.key
end
end