How to crack hashes with John the Ripper – Linux

In this post I will show you how you can crack passwords with John the Ripper. We will start off by collecting the hashes from a linux machine, then use the tool unshadow and at last crack the hashes with John the Ripper.

john the ripper

1 – Collect hashes from a Linux machine
We will start with collecting the hashes from the target machine. We will need both /etc/passwd and /etc/shadow. Save them to your Kali Linux machine, preferably on the desktop. It can be done with the following commands.
cat /etc/passwd > ~/Desktop/passwd.txt

/etc/passwd

cat /etc/shadow > ~/Desktop/shadow.txt

/etc/shadow


2 – Combine passwd and shadow with unshadow
Now we need to combine these two files into one. This can be done with the tool unshadow.
unshadow passwd.txt shadow.txt > hashtocrack.txt

unshadow passwd and shadow files


3 – Crack with John
Now we are ready to crack the hashes. John can run in different modes. You can use wordlists or straight brute force. The method I will use in this example is wordlist mode since that is the most effective way. Brute forcing takes a lot of time and I recommend you to only use it as a last resort when your wordlists won’t crack the hashes. In this example we define the wordlist to use to the built in rockyou.txt.
john --wordlist=/usr/share/wordlists/rockyou.txt hashtocrack.txt

crack with rockyou.txt

4 – Show cracked credentials
If you let john run you will be prompted with the credentials as soon as they have been cracked. In this example we can see that the the password for the user SuperAdmin was Password1.

We can also come back at a later time and check the credentials again by defining the unshadowed file and add the parameter –show.

john hashtocrack.txt --show

//Rickard

How to use Undercover-mode in Kali Linux

Yesterday a new version of Kali Linux were released, Kali 2020.1. You can download it here. Make sure that you have read the release notes to make sure that you don’t break anything you don’t want.

Upgrade your existing machine:

  1. Run sudo apt full-upgrade -y
  2. Wait for the job to finish.
  3. Verify that you got the new version by running
    cat /etc/os-release
    Verify-installation

How to use undercover mode in Kali Linux 2020.1:
Undercover mode is a new feature for version 2020.1 that will help you hide that you are a super elite hacker when you are out in public by temporarily changing the desktop to look like a Windows 10 machine. I’m not sure I see the real use cases for this but it’s actually a funny feature. To use it you just need to run kali-undercover.

Kali undercover

After a few seconds you will see a Windows 10-like appearance, pretty cool.

Windows10-like-Kali-Linux

How to Install Golang in Kali Linux

golang

Golang (Go) is a programming language that are becoming more and more popular and I have seen many interesting tools that are written in Go. Since Go are not being installed by default in Kali Linux I thought that publishing a quick-start guide could be a good idea.

  1. Start by open your web browser and visit https://golang.org/dl/
  2. Download the latest version for Linux – “gox.xx.x.linux-amd64.tar.gz”
    Download page on golang.org
  3. Open your terminal and navigate to your downloads folder
    cd /root/Downloads
  4. Extract the files
    tar -C /usr/local/ -xzf go1.13.6.linux-amd64.tar.gz
  5. Add variables for GO by modifying “~/.bashrc”
    vim ~/.bashrc
    Add the following paths to the end of the file
    export GOPATH=/root/go-workspace
    export GOROOT=/usr/local/go
    PATH=$PATH:$GOROOT/bin/:$GOPATH/bin
  6. Now we need to refresh the bashrc to get the updated variables
    source ~/.bashrc
  7. Now we just need to verify that everything is correct configured and we can do that by creating a simple ‘hello world’ program in Go.
    vim helloworld.go
    Add the following code to the file:
    package main
    import "fmt"
    func main() {
    fmt.Printf("Hello world!\n")
    }
    Then save the file and try to run the program:
    go run helloworld.go
    If everything was configured correctly you should see something like this:
    golang.helloworld
    hackerman1
    You are now ready to use Golang on your Kali Linux machine!

Cewl

This is the first blog post in my series where I will go through all built-in Kali Linux tools. I will write information about how the tools work and give you examples on when to use them. This will be an excellent way for me to learn the tools in depth and hopefully it can come in handy for some of you.
I won’t get much enjoyment if I write about them in one by one from top to bottom since that will be boring. The first tool I will write about is from section 05- Password Attacks and the tool I have chosen to start with is CeWL.

Background and the functionality:
CeWL is a tool that was created by Robin Wood and it is used for creating custom word lists based on the text from a target website. It can come in handy to use this tool if you are doing a pen test and you haven’t been successful with your usual word lists and want to create one that is more customized for the target company.

cewl
CeWL from Kali Linux

CeWL are built in Ruby and the main idea is that the program spiders the specified URL according to the configuration and returns a list of words that was found on that site. These custom word lists can later be used when trying to crack passwords with the other available tools. In a later post I will show you how that is being done.

How to get started with CeWL:
So how do you use CeWL then? It’s pretty easy and straight forward and you can get out the most information from the manual which you get by running “man cewl”. I will go through some of the most common options that you can configure and these are:

  • -w
  • -d
  • -m
  • –with-numbers
  • -c
  • -e

-w
Define where the word list should be saved. example: customwordlist.txt
-d
Define the depth the scan should spider. Default value is 2 and that means that it will go to all links that are presented on the defined URL and collect words from them as well.
-m
Define the minimum length of a word. No words with less characters than this will be saved.

So let’s try it and see how it works in practice. For this example I will just use a website that I know include many words and which site are better than Wikipedia? I’ve set the parameters to depth = 1 and characters = 10.

An example on how to use CeWL to generate a custom word list based on a URL.

It can take some time if you want to spider through many sites but if you use a configuration like mine it will be very quick and in this example I got out 1895 useful words.

wordcount
An example on how you can count the number of files in the file.

–with-numbers
Accept words where numbers are included as well. Like for example the word below. “Riteshkumar1256”.

In the figure you can see the first ten entries in the list that was created.

-c – counts number of entries
If you add the -c parameter the tool will also count how many times each word was found on the site. You can use that for many purposes and one example is that you easy can find out which words the company likes to mention and that might be something users uses in their passwords.

An example on how you can use the -c parameter for CeWL.

-e – includes email addresses
You can also save all email addresses that can be found on the website to a file. Perfect for recon and helps you find mailboxes at the target company. If you also include –email file you can specify where you want to save the emails addresses.

An example on how you can use the -e parameter for CeWL.

That was everything for this time. Please contact me if you feel like I missed something or if you want to share any special tips and tricks for using CeWL?

Thanks
/Rickard

Copyright © 2019