Class: Rex::Encoder::Alpha2::UnicodeMixed

Inherits:
Generic
  • Object
show all
Defined in:
lib/rex/encoder/alpha2/unicode_mixed.rb

Class Method Summary collapse

Methods inherited from Generic

add_terminator, default_accepted_chars, encode, encode_byte

Class Method Details

.gen_decoder(reg, offset) ⇒ Object 



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# File 'lib/rex/encoder/alpha2/unicode_mixed.rb', line 49

def self.gen_decoder(reg, offset)
  decoder =
    gen_decoder_prefix(reg, offset) +
    "j" +               # push 0
    "XA" +              # pop eax, NOP
    "QA" +              # push ecx, NOP
    "DA" +              # inc esp, NOP
    "ZA" +              # pop edx, NOP
    "BA" +              # inc edx, NOP
    "RA" +              # push edx, NOP
    "LA" +              # dec esp, NOP
    "YA" +              # pop ecx, NOP
    "IA" +              # dec ecx, NOP
    "QA" +              # push ecx, NOP
    "IA" +              # dec ecx, NOP
    "QA" +              # push ecx, NOP
    "IA" +              # dec ecx, NOP
    "hAAA" +            # push 00410041, NOP
    "Z" +               # pop edx
    "1A" +              # add [ecx], dh NOP
    "IA" +              # dec ecx, NOP
    "IA" +              # dec ecx, NOP
    "J" +               # dec edx
    "1" +               # add [ecx], dh
    "1A" +              # add [ecx], dh NOP
    "IA" +              # dec ecx, NOP
    "IA" +              # dec ecx, NOP
    "BA" +              # inc edx, NOP
    "BA" +              # inc edx, NOP
    "B" +               # inc edx
    "Q" +               # add [ecx], dl
    "I" +               # dec ecx
    "1A" +              # add [ecx], dh NOP
    "I" +               # dec ecx
    "Q" +               # add [ecx], dl
    "IA" +              # dec ecx, NOP
    "I" +               # dec ecx
    "Q" +               # add [ecx], dh
    "I" +               # dec ecx
    "1" +               # add [ecx], dh
    "1" +               # add [ecx], dh
    "1A" +              # add [ecx], dh NOP
    "IA" +              # dec ecx, NOP
    "J" +               # dec edx
    "Q" +               # add [ecx], dl
    "YA" +              # pop ecx, NOP
    "Z" +               # pop edx
    "B" +               # add [edx], al
    "A" +               # inc ecx       <-------
    "B" +               # add [edx], al         |
    "A" +               # inc ecx               |
    "B" +               # add [edx], al         |
    "A" +               # inc ecx               |
    "B" +               # add [edx], al         |
    "A" +               # inc ecx               |
    "B" +               # add [edx], al         |
    "kM" +              # imul eax, [eax], 10 * |
    "A" +               # add [edx], al         |
    "G" +               # inc edi               |
    "B" +               # add [edx], al         |
    "9" +               # cmp [eax], eax        |
    "u" +               # jnz ------------------
    "4JB"

  return decoder
end

.gen_decoder_prefix(reg, offset) ⇒ Object 



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# File 'lib/rex/encoder/alpha2/unicode_mixed.rb', line 16

def self.gen_decoder_prefix(reg, offset)
  if (offset > 21)
     raise "Critical: Offset is greater than 21"
  end

  # offset untested for unicode :(
  if (offset <= 14)
    nop = 'CP' * offset
    mod = 'IA' * (14 - offset) + nop    # dec ecx,,, push ecx, pop edx
  else
    mod = 'AA' * (offset - 14)			# inc ecx
    nop = 'CP' * (14 - mod.length)
    mod += nop
  end
  regprefix = {                       # nops ignored below
    'EAX'   => 'PPYA' + mod,         # push eax, pop ecx
    'ECX'   =>  mod + "4444",        # dec ecx
    'EDX'   => 'RRYA' + mod,         # push edx, pop ecx
    'EBX'   => 'SSYA' + mod,         # push ebx, pop ecx
    'ESP'   => 'TUYA' + mod,         # push esp, pop ecx
    'EBP'   => 'UUYA' + mod,         # push ebp, pop ecx
    'ESI'   => 'VVYA' + mod,         # push esi, pop ecx
    'EDI'   => 'WWYA' + mod,         # push edi, pop edi
  }

  prefix = regprefix[reg.upcase]
  if prefix.nil?
    raise "Critical: Invalid register"
  end

  return prefix
end

.gen_second(block, base) ⇒ Object 



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# File 'lib/rex/encoder/alpha2/unicode_mixed.rb', line 11

def self.gen_second(block, base)
  # unicode uses additive encoding
  (block - base)
end