automating_2.py

from capstone import *
data = open('flag.exe', 'rb').read()
md = Cs(CS_ARCH_X86, CS_MODE_64)
with open('asm.txt', 'w') as f:
  for i in md.disasm(data[0x914:0x85fd], 0x00401514): #Capstone read from data address, not the virtual address
    f.write("0x%x:\t%s\t%s\n" %(i.address, i.mnemonic, i.op_str))
  f.close()
  
byte = []
key = []

status = True

with open('asm.txt', 'r') as f:
    for line in f.readlines():
        if (line.find('mov	dword ptr [rbp - 0x10]') != -1):
            if (status):
                key.append(0x0)
            pos = line.find(',')
            item = line[pos+2:-1]
            byte.append(int(item,16))
            status = True
        elif (line.find('xor') != -1):
            pos = line.find(',')
            item = line[pos+2:-1]
            key.append(int(item,16))
            status = False

flag = ''

for i in range(len(byte)):
    flag += chr(key[i+1]^byte[i])

print flag