All we got is a file and regular expression.

Lets run file command on the file to determine its type:

$ file ./file.kdb
file: Keepass password database 1.x KDB, 3 groups, 4 entries, 50000 key transformation rounds

The file is KDB file which is Keepass password database. Keepass is a famous opensource password manager.

I tried open it using KeePassX for windows, but we need a password to open the database. The password probably should match the regex, so I generated a dictionary with all the possible passwords (more then 300,000 words).

import string
import itertools

# strings match the regex
chars = string.lowercase + string.uppercase + string.digits + '!@#$%^&*'
f = open('dict.txt','a')

all_permutations = list(itertools.permutations(chars,1))+ list(itertools.permutations(chars,2))+ list(itertools.permutations(chars,3))

for p in all_permutations:
    f.write(''.join(p)+'\n')

 

$ keepass2john file.kdb > kp
$ john  --wordlist=dict.txt -format:keepass kp
Using default input encoding: UTF-8
Loaded 1 password hash (KeePass [SHA256 AES 32/64 OpenSSL])
Press 'q' or Ctrl-C to abort, almost any other key for status
k18              (file.kdb)