password_reuse.py

#!/usr/bin/python

'''
This script can be used to identify passwords that are being used across multiple accounts.
Example: python3 password_reuse.py <file in username:hash format>
'''

import sys
from pprint import pprint
from collections import defaultdict

if len(sys.argv) != 2:
    print('Usage: {} <hash file in username:hash format>'.format(sys.argv[0]))
    sys.exit()

hash_file = sys.argv[1]

data = [line.rstrip() for line in open(hash_file).readlines()]
d = defaultdict(list)

for line in data:
    username, password_hash = line.split(":")
    d[password_hash].append(username)

for nt_hash in d:
    if len(d[nt_hash]) > 1:
        print("{} - {}".format(nt_hash, d[nt_hash]))