flip_cryptid.py

#!/usr/bin/env python
'''
This program simply flip cryptid to \x00, given offset.
WARNING: this will modify binary directly and without checking structure,
backup, and using with caution!
'''
import sys, os

def parse_arg(argv):
    if len(argv) != 3:
        print 'Usage: %s <Mach-O File> <cryptid offset>' % argv[0]
    elif not 'Mach-O' in [i.rstrip() for i in os.popen('file %s' % argv[1])][0]:
        print 'The first argument must be Mach-O binary file.'
    else:
        try:
            offset = int(argv[2])
            return open(argv[1], 'rb+'), offset
        except ValueError:
            print 'Invaild offset'
    exit()

if __name__ == '__main__':
    f, offset = parse_arg(sys.argv)
    f.seek(offset)
    f.write('\x00\x00\x00\x00')
    f.close()
    print "Flip cryptid located in %08X (%s) for %s" % (offset, offset, f.name)