Kali Linux - An Ethical Hacker's Cookbook

Kali - An Introduction

Kali was first introduced in 2012 with a completely new architecture. This Debian-based distribution was released with over 300 specialized tools for penetration testing and digital forensics. It is maintained and funded by Offensive Security Ltd, and the core developers are Mati Aharoni, Devon Kearns, and Raphaël Hertzog.

Kali 3.0 came into the picture in 2018 with tons of new updates, bug fixes such as AMD Secure Memory Encryption Support, and increased memory limits.

In the previous edition of this book, we saw some of the great tools in Kali that help penetration testers around the globe to perform their job efficiently. In this chapter, we will primarily cover the installation of Kali and setting up different desktop environments, as well as some custom tools that will help us.

In this chapter, we will cover the following recipes:

Configuring Kali Linux
Configuring the Xfce environment
Configuring the MATE environment
Configuring the LXDE environment
Configuring the E17 environment
Configuring the KDE environment
Prepping Kali with custom tools
Zone Walking using DNSRecon
Setting up I2P for anonymity
Pentesting VPN's ike-scan
Setting up proxychains
Going on a hunt with Routerhunter

Prepping with custom tools

In this recipe, we will set up a few tools beforehand; not to worry, we will be covering their usage in detail in later chapters.

Getting ready

Here is a list of some tools that we will need before we dive deeper into penetration testing. Don't worry, we will learn about their usage with some real-life examples in the next few chapters. But those of us who are excited about them right now can run the following simple commands to view the -help section where toolname is the name of the tool we would like to view the help of:

toolname -help
toolname -h

How to do it...

We will be looking at two tools in this section.

Aquatone

Aquatone is a tool for visually inspecting websites across a large amount of hosts and is convenient for quickly gaining an overview of an HTTP-based attack surface. Aquatone has four major modules: discover, scanner, gather, and takeover. Each of these can be used to perform in-depth enumeration of a target:

We will use a simple command to install aquatone:

gem install aquatone

The following screenshot shows the output of the preceding command:

Next, we create a directory in /root/folder using the following command:

mkdir /root/aquatone/

As aquatone uses different modules to hunt for subdomains, we will have to configure aquatone's discovery module before running it.
For example, to configure the shodan, we can use the following command:

aquatone-discover --set-key shodan XXXXXXXXXXX

The following screenshot shows the output of the preceding command:

Similarly, we can set keys for other services too, such as Censys and PassiveTotal.
Once it is all set, we can start our subdomain hunting. We can do this using the following command:

aquatone-discover -d domain.com

The following screenshot shows the output of the preceding command:

Aquatone also allows us to set a custom wordlist by using the -w flag, and we can also set the threads by using the -t flag.
By default, aquatone stores the output in TXT as well as JSON format in the /root/aquatone/ directory.
After we find the subdomains, we can use the aquatone scanner to scan for open ports on the discovered hosts. Let's look at an example:

aquatone-scan --ports 80 -d packtpub.com

The following screenshot shows the output of the preceding command:

This will look for the domain's hosts.json file in the aquatone directory.
Aquatone by default has four inbuilt port scanning flags (small, medium, large, and huge). These flags will decide the number of ports being scanned on the hosts, or we can define custom ports by using the -ports flag.
- aquatone-gather: This tool makes a connection to the web services found using the discover and scanner modules of aquatone and takes screenshots of discovered web pages for later analysis.
- aquatone-takeover: This module is used to find subdomains that are vulnerable to the subdomain takeover vulnerability.

Let's refer to the following screenshot:

Subfinder

Subfinder is considered as a successor to sublist3r. It is amazingly fast and finds valid subdomains using passive online sources such as Ask, Archive.is, Baidu, Bing, Censys, CertDB, CertSpotter, Commoncrawl, CrtSH, DnsDB and so on.

Install subfinder. It needs Go to be installed, which we can install by using the following command:

apt install golang

The following screenshot shows the output of the preceding command:

Next, we clone subfinder by using the following command:

git clone https://github.com/subfinder/subfinder.git

The following screenshot shows the output of the preceding command:

Or you can download and save it from https://github.com/subfinder/subfinder.

To install subfinder, we go to the cloned directory and run the go build command.
Once the installation is complete, we will need a wordlist for it to run, so we can download dnspop's list. This list can be used in the previous recipe too: https://github.com/bitquark/dnspop/tree/master/results.
Now that both are set up, we browse into subfinder's directory and run it using the ./subfinder -h command.

The following screenshot shows the output of the preceding command:

To run it against a domain with our wordlist, we use the following command:

./subfinder -w /path/to/wordlist -d hostname.com

If we do not specify a wordlist the tool will run with a default wordlist as shown in the following screenshot:

Once the enumeration is complete, the output will be shown onscreen as follows:

Subfinder is also designed to work with services such as shodan, censys, and virustotal, but they need to be configured in the config.json file shown here:

There's more...

A subdomain takeover vulnerability exists when a service that previously pointed to a subdomain is removed but the CNAME record still exists. More information can be read about it at the following GitHub link: https://github.com/EdOverflow/can-i-take-over-xyz/.

Aquatone-takeover is based on the same methodology described by EdOverflow at the preceding URL.

Zone Walking using DNSRecon

Zone Walking is a technique that is used by attackers to enumerate the full content of DNSSEC-signed DNS zones. We will cover more about it in later chapters; in this recipe, we will use DNSRecon.

Getting ready

DNSRecon is already included in Kali Linux, and we can use it for Zone Walking. Zone Walking is a technique used to find subdomains using domains whose NSEC records are set. However, before we jump into Zone Walking, let's take a quick look at the other features of this tool.

How to do it...

To view the help, we type the following:

dnsrecon -h

The following screenshot shows the output of the preceding command:

To do a simple recon of name servers, A records, SOA records, MX records, and so on, we can run the following command:

dnsrecon -d packtpub.com -n 8.8.8.8

The following screenshot shows the output of the preceding command:

Now let's take an example of a domain that has NSEC records. To do a zone walk, we can simply run the following command:

dnsrecon -z -d icann.org -n 8.8.8.8

The following screenshot shows the output of the preceding command:

We can do this manually by using the dig command along with dig +short NSEC domainname.com.
The previous dig command will throw us one subdomain, and then we can rerun the same command with the subdomain we got in previous step to find the next subdomain: dig +short NSEC a.domain.com.

There's more...

When signing a zone, DNSSEC automatically chains all labels in alphabetical order using NSEC Resource Records. This is used to prove the absence of names.

For example, if someone requests the non-existent name name3, the name server responds with the NSEC entry name2 NSEC name5, indicating that no other entry exists between name2 and name5. We take advantage of that by starting with the first entry and then getting all domains by calling successive queries and getting other subdomains.

Pentesting VPN's ike-scan

During a pentest, we may encounter VPN endpoints. However, finding vulnerabilities in those endpoints and exploiting them is not a well-known method. VPN endpoints use the Internet Key Exchange (IKE) protocol to set up a security association between multiple clients to establish a VPN tunnel.

IKE has two phases. Phase 1 is responsible for setting up and establishing a secure authenticated communication channel. Phase 2 encrypts and transports data.

Our focus of interest here is Phase 1. It uses two methods of exchanging keys:

Main mode
Aggressive mode

We hunt for Aggressive-mode-enabled VPN endpoints using PSK authentication.

Getting ready

For this recipe, we will use the ike-scan and ikeprobe tools. First, we install ike-scan by cloning the Git repository:

git clone https://github.com/royhills/ike-scan.git

Or, you can use the following URL: https://github.com/royhills/ike-scan.

How to do it...

Browse to the directory where ike-scan is installed.
Install autoconf by running the following command:

apt-get install autoconf

Run autoreconf --install to generate a .configure file.
Run ./configure.
Run make to build the project.
Run make check to verify the building stage.
Run make install to install ike-scan.
To scan a host for an Aggressive mode handshake, use the following command:

   ike-scan x.x.x.x –M -A

The following screenshot shows the output of the preceding command:

Sometimes, we will see the response after providing a valid group name such as vpn:

ike-scan x.x.x.x –M –A id=vpn

To view the list of all available options, we can run the following command:

ike-scan -h

The following screenshot shows the output of the preceding command:

We can even brute force the group names using the following link: https://github.com/SpiderLabs/groupenum.
Here is the command:
./dt_group_enum.sh x.x.x.x groupnames.dic

Cracking the PSK

Adding a –P flag in the ike-scan command will show a response with the captured hash.
To save the hash, we provide a filename along with the –P flag.
Next, we can use psk-crack with the following command:

psk-crack –b 5 /path/to/pskkey

-b is brute force mode and length is 5.

To use a dictionary-based attack, we use the following command with -d flag to input the dictionary file:

psk-crack –d /path/to/dictionary /path/to/pskkey

The following screenshot shows the output of the preceding command:

There's more...

In Aggressive mode, the authentication hash is transmitted as a response to the packet of the VPN client that tries to establish a connection tunnel (IPSec). This hash is not encrypted and hence it allows us to capture the hash and perform a brute force attack against it to recover our PSK.

This is not possible in Main mode, as it uses an encrypted hash along with a 6-way handshake, whereas Aggressive mode uses only a 3-way handshake.

Setting up proxychains

Sometimes, we need to remain untraceable while performing a pentest activity. Proxychains helps us by allowing us to use an intermediary system whose IP can be left in the logs of the system without the worry of it tracing back to us.

Proxychains is a tool that allows any application to follow the connection via proxy, such as SOCKS5 and Tor.

How to do it...

Proxychains is already installed in Kali. However, we need a list of proxies in its configuration file that we want to use:

To do that, we open the config file of proxychains in a text editor with this command:

leafpad /etc/proxychains.conf

The following screenshot shows the output of the preceding command:

We can add all the proxies we want in the place highlighted in the previous screenshot and then save. Proxychains also allows us to use dynamic chain or random chain while connection to proxyservers.

In the config file, uncomment dynamic_chain or random_chain. The following screenshot shows the output of the preceding command:

Using proxychains with Tor

To use proxychains with Tor, we first need to install Tor using the following command:

apt-get install tor

Once it is installed, we run Tor by typing tor in the Terminal.
We then open another Terminal and type the following command to use an application via proxychains:

proxychains toolname –arguments

The following screenshot shows the output of the preceding command:

Now let's have a look at the Routerhunter tool in the next recipe.

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Amazon verified reviews

Yehia Serrieh May 27, 2019

if you need very detailed book so you can master kali with all tools included plus nethunter then this is your book, do you want to master pentest and writing very organized report then this is your book it worth every cent you will pay for it

Amazon Verified review

Antonio Garcia Dec 07, 2019

Sehr gut!

Yoonus Ibrahim Aug 28, 2019

awesome

IndianWeeboo Nov 09, 2019

Great book but the screenshots are not so clear.

Jonathan B. Aug 15, 2020

Excellent introduction to Kali. Based on the description I would have thought there was more detail and content than there was though.The font was large which makes it easy to read but also a lot less content than I expected there to be. I’m a slow reader and was reading 120 pages a day.Otherwise it was great, learnt quite a bit even though I’ve been using Kali for a while. I will however be looking for more detailed books.