Saturday, December 2, 2023

John the Ripper – Pentesting Tool for Offline Password Cracking to Detect Weak Passwords


John the Ripper is a  fast password cracker that is intended to be both elements rich and quick.

It combines a few breaking modes in one program and is completely configurable for your specific needs for Offline Password Cracking.

Out of the create, John the Ripper tool underpins (and autodetects) the accompanying Unix crypt(3) hash sorts: conventional DES-based, “big crypt”, BSDI broadened DES-based, FreeBSD MD5-based (additionally utilized on Linux and in Cisco IOS), and OpenBSD Blowfish-based (now likewise utilized on some Linux dispersions and bolstered by late forms of Solaris).

Additionally bolstered out of the case are Kerberos/AFS and Windows LM (DES-based) hashes and in addition DES-based tripcodes.

John the Ripper is accessible on several different platforms which empower you to utilize a similar cracker everywhere.

John the Ripper Pro includes support for Windows NTLM (MD4-based) and Mac OS X 10.4+ salted SHA-1 hashes.

Also Read: Online Password Bruteforce Attack With THC-Hydra Tool -Tutorial

Extracting hashes From Linux

Every Linux user know that the passwords hashed are stored in /etc/passwd, one can see the file using the command root@kali:~# cat /etc/passwd

John the Ripper

We can see the password hashed as X, to unmask the password we should use unshadow to unmask the passwords.

root@kali:~# unshadow

Now you should use the unshadow command in order to unmask/decrypt the passwords.

root@kali:~# unshadow /etc/passwd /etc/shadow > hashfile

/etc/passwd : Password location   /etc/shadow : Shadow file  hashfile : Output file

John the Ripper
John the Ripper

Now you can see the X has been replaced with the actual hash values.

John the Ripper

We can There are various cracking modes available with John the Ripper, we are to use a simple and powerful wordlist mode.

root@kali:~# john –wordlist=/usr/share/john/password.lst hashfile

The cracked passwords are stored in john.pot which can be accessible with the command root@kali:~# cat /root/.john/john.pot

John the Ripper

It’s done we can see the password:test123  displayed on the screen.

Extracting hash dumps from Windows machine

Pwdump is a significant simple handy tool to yield the LM and NTLM secret word hashes of local client accounts from the Security Account Manager (SAM).

John the Ripper

Download and extract the pwdump in the working directory.

Simply by typing pwdump in the command prompt, we can retrieve the local client account hashes from the SAM database.

Also, we can extract the hashes to the file pwdump7 > hash.txt

Offline Password Cracking with John the Ripper

John the Ripper is intended to be both elements rich and quick. You can get all the possible options by typing root@kali:~# john -h

John the Ripper

To list all the possible formats root@kali:~# john –list=formats

John the Ripper

To list all the possible subformats root@kali:~# john –list=subformats

John the Ripper

To bruteforce the root@kali:~# john -format=LM /root/Desktop/hash.txt

John the Ripper

It will take some time to get the password cracked.

In final words, John the Ripper is a fantastic tool for offline password cracking. Don’t use it for offensive purposes.

Author credits:

  • Author: Solar Designer
  • License: GPLv2

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