20160316

John the Mangler

When using the password cracking tool John the Ripper, I have many times used it against the LM passwords, and cracked them with a bit of time.  Of course the NT passwords are (usually) just a case permutation of the LM password.  So, there must be an easy way to get John to do case permutations for you.  I went in to the configuration file -- /etc/john/john.conf to see if I could figure out how john word mangling rules are made.  I did not, but discovered there is already a rule to get NT passwords from LM passwords.  To use it, simply specify the mangling rule.

In sequence, I did this (assume the hashes are in a file called hashes) --

time john --format=LM hashes (this took about two hours)


john --format=LM --show hashes | cut -d : -f 2 | sort | tail -n 5 > word.txt

time john --format=nt --rules=NT -w:word.txt hashes (this took less than 0.1 seconds).

No video this time, comment if there's a part you don't understand, and I'll break it down.

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