Password cracking with John the Ripper on Linux Introduction. For those of you who haven't yet heard about John the Ripper (hereby called John for brevity), it is a. Installing John. Although, at least on the distributions we tried, the package in named simply 'john' with Gentoo making. Learn how to crack /etc/shadow file using John the Ripper. Thu 09 Jan 2020 /Hacking/Cracking; In this article we are going to show how we can crack /etc/shadow file using John the Ripper. It is common in CTF like events to somehow get access to the shadow file or part of it and having to crack it so you can get the password of a user. John the Ripper (also called simply ‘ John ’) is the most well known free password cracking tool that owes its success to its user-friendly command-line interface. John has autodetect capability. John the Ripper can also crack UNIX/Linux passwords. You need root access to your system and to the password (/etc/passwd) and shadow password (/etc/shadow) files. Perform the following steps for cracking UNIX/Linux passwords: Download the UNIX source files from www.openwall.com/john. Cracking raw MD5 hashes with John the Ripper. And of course I have extended version of John the Ripper that support raw-md5 format. Installation (9) linux (60.
In this article we are going to show how we can crack /etc/shadow file using John the Ripper. It is common in CTF like events to somehow get access to the shadow file or part of it and having to crack it so you can get the password of a user.
The process involves two basic steps, the first is called unshadowing while the second is the cracking itself. Unshadowing is a process where we combine the /etc/passwd file along with the /etc/shadow in order for John to be able to understand what we are feeding to it. Unshadow is a tool that handles this task and it is part of the John package. In order to unshadow the shadow file we need to also have the equivalent line from the passwd for the user of our interest. An example is the following:
In order to unshadow to the two files we need to execute
Which will store in the unshadowed.txt file the following
Next and final step is to actually start the cracking with John. It is up to you which cracking method you will chose, though a bruteforcing using a wordlist is usually enough for CTFs. An example attack using a wordlist would be launched like below
The result would be similar to the following picture
Where as we see John managed to crack the password of the user root as it was included in the wordlist used.
If you would like to print all the passwords John managed to crack you may run john --show unshadowed.txt and you will get something like:
Conclusion
Crack Htpasswd John The Ripper Linux Iso
In this article we showed how John the Ripper can be used to crack the hashed password of a user that can be found in the /etc/shadow file. The process is pretty simple and straightforward yet if you find yourself stuck somewhere please feel free to reach out to me.
I just spent at least 15 minutes trying to figure out why every single post on the Internet tells me to place MD5 hash in a file and call John like thisjohn --format=raw-md5 --wordlist=/usr/share/dict/words md5.txtand yet, it constantly gives me an error message:
No password hashes loaded (see FAQ)The content of md5.txt was:
20E11C279CE49BCC51EDC8041B8FAAAAI even tried prepending dummy user before this hash, like this:
dummyuser: 20E11C279CE49BCC51EDC8041B8FAAAA
Crack Password Hash John The Ripper
but without any luck.And of course I have extended version of John the Ripper that support raw-md5 format.
It turned out that John doesn't support capital letters in hash value! They have to be written in small letters like this:
20e11c279ce49bcc51edc8041b8fbbb6after that change, everything worked like a charm.
What a stupid error!?