0x57 위치에 무조건 0x40을 씁니다.

change.py

from os import getcwd, listdir
from sys import argv

cwd = getcwd()
list = listdir(cwd)
list.remove(argv[0])

for i in list:
    fp = open(i, 'rb')
    buf = fp.read()
    fp.close()
    buf = buf[:87] + b'\x40' + buf[88:]
    fp = open(i + '_', 'wb')
    fp.write(buf)

print '[*] %d files changed' % len(list)