I am going to demonstrate two ways in which we will crack the user credentials using John the Ripper.
So, before diving in, we need to know what a shadow file is.
A shadow password file, also known as /etc/shadow, is a system file in Linux that stores encrypted user passwords and is accessible only to the root user, preventing unauthorized users or malicious actors from breaking into the system.
Now for the First method, I am going to crack the credentials of a particular user “EthicalEmpire”
- Primarily we will open a shadow file using the command “cat /etc/shadow”
- Now I will change the password of the user “EthicalEmpire” for demonstration purposes. I updated my password to “admin”.
- Now I will copy the credentials of the user “EthicalEmpire” and copy it from here and paste it into a text file.
- Here is a text file named Ethical Empire.
- Now I will use John the Ripper to crack it, Here I will use wordlist as a rockyou.txt, path in Kali Linux as “/usr/share/wordlists/rockyou.txt” and format as “crypt”
Command as follows – “john –wordlist=/usr/share/wordlists/rockyou.txt –format=crypt EthicalEmpire”
- We successfully cracked the password for the user EthicalEmpire.
I will now collectively crack all of the users’ credentials for the second method.
We will need to use John the Ripper’s “unshadow” utility to accomplish this and also the “/etc/passwd” file; which is used to keep track of every registered user that has access to a system.
- Firstly I will change the password of all users for demonstration purposes. I updated all user’s passwords as a “Kali”
- Now I will use a utility called unshadow, command “unshadow /etc/passwd /etc/shadow > unshadowed.txt”
- Here a file name saved as unshadowed.txt
- Now I will use John the Ripper to crack the passwords of all the users collectively.
- Here I used the same format as the crypt and a custom wordlist of my own where I didn’t give too many passwords so that it could brute force the password quickly, named “wordl.txt” for demonstration purposes. You can use any word list of your choice.
Command as Follow – “john -w=/usr/share/wordlists/rockyou.txt -form=crypt unshadowed.txt”
- As you can see from the above result, we have successfully cracked the credentials of all the users.