xor algo used in an APT1 sample

decode_apt1.py

#!/usr/bin/python

# encoded data
encoded = []
encoded.append([0x2D, 0xC8, 0xD4, 0xDD, 0xCF, 0xCC, 0xDA, 0xC9, 0xDE, 0xC7, 0xD6, 0xF2, 0xF8, 0xE9, 0xF4, 0xE8, 0xF4, 0xFD, 0xEF, 0xC7, 0xCC, 0xF2, 0xF5, 0xFF, 0xF4, 0xEC, 0xE8, 0xC7, 0xD8, 0xEE, 0xE9, 0xE9, 0xFE, 0xF5, 0xEF, 0xCD, 0xFE, 0xE9, 0xE8, 0xF2, 0xF4, 0xF5, 0xC7, 0xC9, 0xEE, 0xF5, 0xB6, 0x00])
encoded.append([0x08, 0x21, 0x0F, 0x39, 0x1C, 0x08, 0x0D, 0x18, 0x09, 0x64, 0x00])
encoded.append([0x26, 0xB2, 0xAE, 0xAE, 0xAA, 0xE0, 0xF5, 0xF5, 0xE8, 0xEB, 0xEC, 0xF4, 0xEB, 0xEF, 0xF4, 0xE8, 0xEB, 0xEA, 0xF4, 0xEC, 0xE2, 0xF5, 0xEB, 0xE3, 0xED, 0xF4, 0xEB, 0xF4, 0xEB, 0xEC, 0xF4, 0xE9, 0x85, 0xED, 0xF4, 0xB2, 0xAE, 0xB7, 0xB6, 0xFC, 0x0, 0x0])
encoded.append([0x32, 0x3D, 0x1F, 0x0A, 0x19, 0x1C, 0x1C, 0x11, 0x5F, 0x44, 0x5E, 0x40, 0x50, 0x58, 0x13, 0x1F, 0x1D, 0x00, 0x11, 0x04, 0x19, 0x12, 0x1C, 0x15, 0x4B, 0x50, 0x3D, 0x23, 0x39, 0x35, 0x50, 0x46, 0x5E, 0x40, 0x4B, 0x50, 0x27, 0x19, 0x1E, 0x14, 0x1F, 0x07, 0x03, 0x50, 0x3E, 0x24, 0x50, 0x45, 0x5E, 0x41, 0x59, 0x42, 0x00])
encoded.append([0x0C, 0x48, 0x55, 0x59, 0x59, 0x54, 0x30, 0x3B, 0x37, 0x3C, 0x20, 0x39, 0x38, 0x78, 0x00])
encoded.append([0x04, 0x70, 0x7D, 0x7D, 0x6E, 0x54, 0x00])
encoded.append([0x05, 0x32, 0x06, 0x00, 0x1C, 0x05, 0x76, 0x00])
encoded.append([0x06, 0xD3, 0xE7, 0xE6, 0xFA, 0xFD, 0xE0, 0x94, 0x00])
encoded.append([0x07, 0xF9, 0xE5, 0xE5, 0xE1, 0xAB, 0xBE, 0xBE, 0x96, 0x00])
encoded.append([0x03, 0xD5, 0xC8, 0xD5, 0xB3, 0x00])

def decode_data(encoded):
  decoded = [0] * 0x100
  
  char = encoded[0]
  xor_char = encoded[char+1] ^ char
  
  i = 0
  
  while i < char:
    decoded[i] = encoded[i+1] ^ xor_char
    i += 1
  
  res = ""
  for j in decoded:
    res += chr(j)
  print "%s : %s"% (encoded, res)

for e in encoded:
  decode_data(e)