In my earlier days I always had a doubt about how the passwords are stored. When I studied Linux, I found that passwords are stored in /etc/shadow in a hashed format. What will happen if someone takes a copy of this file and try to recover the password. I asked this question to my instructor, but he told me that hashed passwords can’t be recovered and only root user will be able to access this file. I was aware of brute force and dictionary attacks at that time and using those methods, we won’t be able to crack a hashed password.
In 2012, I read about Linkedin password breach and was surprised to see that hashed passwords are getting cracked. How is this possible? The research went to find something known as Rainbow table.