John Ripper is a fast password cracker currently available for many variants of
Unix, macOS, Windows, DOS, BeOS, and OpenVMS. Its primary purpose is to detect weak Unix passwords. In addition to the hash type of several crypt passwords most commonly found in various Unix codes, Kerberos / AFS and Windows LM hashes, as well as DES-based tripcodes and hundreds of additional hash and encryption versions in -jumbo.
In this article, we will now see how to crack and obtain a PDF password by attacking Brute Force with John The Ripper.
We will open
Kali Terminal and extract the
JohnTheRipper ("bleeding-jumbo" 1.8.0-Jumbo-1 based) source code from the repository in
Github with the following command.
git clone https://github.com/magnumripper/JohnTheRipper.git
This creates a directory named JohnTheRipper in the current directory. Switch to JohnTheRipper’s src directory with the following command:
We download the necessary packages with the following command.
sudo apt-get update
Now we install libssl:
sudo apt-get install libssl-dev
After the package has been copied, we continue to enter the source directory containing the
JohnTheRipper source code:
We continue compiling in this directory with the following command:
./configure && make
This version of Jumbo has Autoconf, which supports the very common chain that allows us to compile resources on a Unix-like system. When the compilation is finished, we move to the working directory inside the JohnTheRipper directory:
If we want to see all the packages downloaded and welcome, we can use the code below.
In this series, we can see all packages of JohnTheRipper.
Now that we have the necessary tools, we can start the Brute Force attack.
Now we need to create the hash file of the PDF using the
pdf2john.pl tool. This tool allows us to get the hash of the file with this Perl script, which can be extracted to a new file with the following command:
pdf2john.pl /home/kali/Desktop/Cembarut_protected.pdf > /home/kali/Desktop/cembarut_com_tr.hash
This command creates a file in the .hash defined directory. The file we will use to work with the JohnTheRipper tool is:
cembarut_com_tr.hash Contains text such as the file:
Now we have the .hash file, we need to prepare our Password List before we can make
Brute Force using the john CLI tool.
For this, we will use the
Crunch program in Kali
Here we have created numbers of 0-8 digits.
You can access it from
Password Attacks> Crunch section.
crunch 0 8 0123456789 /home/kali/Desktop/pass.ls
You can find detailed information on this page to generate 0 8 = 8 digit numbers.
The password list is generated, but this may take some time.
Now that we have the
.hash file of the PDF containing the password we want to unlock, we need to migrate the file independently to JohnTheRipper’s (in the run directory) CLI tool.
./john --wordlist=pass.lst cembarut_com_tr.hash
UTF-8 as the default input encoding and starts guessing the password of the PDF file using the password list we created. Displays the password and path of the protected PDF, if found:
I hope it was a useful article.