🚧 Brute Force Web Password Cracking

Introduction

In this lab, you will learn about brute force password cracking, a technique used for compromising web applications by guessing login credentials. The goal of this lab is to gain hands-on experience in using a popular password cracking tool, Hydra, against a vulnerable web application, and understand the principles and implications of brute force attacks. This lab will provide you with a practical understanding of how brute force attacks work, and how to defend against them.

Understanding Brute Force Attacks

In this step, you will learn about the fundamentals of brute force attacks.

Brute force attacks, also known as exhaustive key search, are a method of attempting to guess passwords, encryption keys, or other forms of authentication by systematically trying every possible combination of characters until the correct one is found. This technique relies on the fact that most password-based authentication systems have a relatively small set of possible character combinations, making it computationally feasible to try all possible combinations.

Brute force attacks can be executed in several ways:

1. Combination Attacks: This method involves trying every possible combination of characters, including letters (uppercase and lowercase), numbers, and special characters. This approach is computationally intensive and often requires powerful hardware and optimized algorithms.

2. Dictionary Attacks: This method uses pre-compiled lists of commonly used passwords, known as "dictionaries," to try and guess the correct password. These dictionaries can be generated based on various factors, such as common words, names, dates, and patterns.

3. Hybrid Attacks: This method combines both combination and dictionary attacks, increasing the probability of success by expanding the search space.

While brute force attacks can be effective against weak passwords, they become increasingly difficult as password complexity and length increase. Therefore, it is essential to follow best practices for password security, such as using long, complex passwords and enabling additional security measures like multi-factor authentication.

Hydra Setup and Configuration

In this step, you will set up the Hydra tool and prepare for the brute force attack.

Hydra is a popular open-source password cracking tool that can be used to launch brute force attacks against various protocols, including HTTP, FTP, SSH, and more. It supports a wide range of attack types, such as dictionary attacks, combination attacks, and hybrid attacks.

To set up Hydra, follow these steps:

1. Open a new terminal window.

2. Update the package lists:

sudo apt-get update

3. Install Hydra:

sudo apt-get install hydra

After the installation is complete, you can verify the installation by running:

hydra -h

This should display the help menu for Hydra, indicating that the tool has been successfully installed.

Next, you'll need to prepare wordlists (dictionaries) for the brute force attack. Wordlists are text files containing lists of potential usernames and passwords to be tried during the attack. You can create your own wordlists or use publicly available wordlists.

Create a new directory called wordlists in your home directory:

mkdir ~/wordlists

Inside the wordlists directory, create two files: usernames.txt and passwords.txt. You can use a text editor like nano or vim to add some potential usernames and passwords to these files.

For example, in usernames.txt, you could add:

admin
test
user1
john

And in passwords.txt, you could add:

password123
qwerty
letmein
admin123

These wordlists will be used by Hydra during the brute force attack.

Setting up the Vulnerable Web Application

In this step, you will set up a vulnerable web application that you will attempt to brute force.

For this lab, we will use a deliberately vulnerable web application called DVWA (Damn Vulnerable Web Application). DVWA is a PHP/MySQL web application that is designed to be insecure for educational purposes.

Follow these steps to set up DVWA:

1. Open a new terminal window.

2. Install Docker if you haven't already:

sudo apt-get update
sudo apt-get install docker.io

3. Pull the DVWA Docker image:

sudo docker pull vulnerables/web-dvwa

4. Run the DVWA container:

sudo docker run --rm -it -p 8080:80 vulnerables/web-dvwa

This will start the DVWA container and map port 8080 of your local machine to port 80 of the container.

5. Open a web browser and navigate to http://localhost:8080. You should see the DVWA login page.

6. Log in with the default credentials:

   • Username: admin
   • Password: password

7. After logging in, go to the "DVWA Security" page and set the security level to "Low". This will make the application more vulnerable for the purposes of this lab.

Now, DVWA is set up and ready for you to attempt a brute force attack against its login page.

Launching the Brute Force Attack

In this step, you will use Hydra to perform a brute force attack against the DVWA login page.

The general syntax for running a brute force attack with Hydra against an HTTP login form is:

hydra -L <usernames_file> -P <passwords_file> <target_ip> http-get-form "<login_page>:<request_body>:<fail_pattern>"

Here's what each part of the command means:

• -L <usernames_file>: Specifies the file containing the list of usernames to try.
• -P <passwords_file>: Specifies the file containing the list of passwords to try.
• <target_ip>: The IP address or hostname of the target web application.
• http-get-form: Tells Hydra to perform a brute force attack against an HTTP login form.
• <login_page>: The URL of the login page.
• <request_body>: The HTTP request body containing the username and password fields.
• <fail_pattern>: A string that Hydra should look for in the response to identify a failed login attempt.

For the DVWA login page, the command would look like this:

hydra -L ~/wordlists/usernames.txt -P ~/wordlists/passwords.txt localhost http-get-form "/login.php:username=^USER^&password=^PASS^&Login=Login:F=log\?pwd=wrong" -V

Here's what each part of the command means:

• -L ~/wordlists/usernames.txt: The file containing the list of usernames to try.
• -P ~/wordlists/passwords.txt: The file containing the list of passwords to try.
• localhost: The target IP address or hostname (in this case, it's running locally).
• http-get-form: Tells Hydra to perform a brute force attack against an HTTP login form.
• /login.php: The URL of the DVWA login page.
• username=^USER^&password=^PASS^&Login=Login: The HTTP request body containing the username and password fields.
• F=log\?pwd=wrong: The string that Hydra should look for in the response to identify a failed login attempt.
• -V: Enables verbose mode, which displays more detailed output.

Run the command in your terminal, and Hydra will start trying different username and password combinations against the DVWA login page. Once it finds a valid combination, it will display the credentials.

Note that this process can take a long time, depending on the size of your wordlists and the complexity of the passwords.

Defending Against Brute Force Attacks

In this step, you will learn about some common techniques for defending against brute force attacks.

While brute force attacks can be effective against weak or default passwords, there are several measures that can be implemented to mitigate the risk:

1. Strong Password Policies: Enforcing strong password policies that require a minimum length, a mix of character types (uppercase, lowercase, numbers, and special characters), and regular password changes can significantly reduce the likelihood of successful brute force attacks.

2. Account Lockout Policies: Implementing account lockout policies that temporarily lock an account after a certain number of failed login attempts can prevent brute force attacks from continuing indefinitely.

3. Multi-Factor Authentication (MFA): Adding an additional layer of authentication, such as a one-time password or biometric authentication, can make it much more difficult for an attacker to gain unauthorized access, even if they have the correct password.

4. Captcha or Puzzles: Requiring users to solve a CAPTCHA or puzzle during the login process can slow down automated brute force attacks and increase the computational resources required to carry out the attack.

5. IP Throttling or Blocking: Monitoring and limiting the number of login attempts from a single IP address or network can help prevent brute force attacks from a single source.

6. Monitoring and Logging: Implementing proper monitoring and logging mechanisms can help detect and respond to brute force attacks in a timely manner.

It's important to note that while these measures can significantly reduce the risk of successful brute force attacks, they should be combined with other security best practices, such as keeping software up-to-date and following the principle of least privilege.

Summary

In this lab, you learned about brute force password cracking, a common technique used by attackers to gain unauthorized access to web applications. You set up a vulnerable web application (DVWA) and used the Hydra tool to launch a brute force attack against its login page. Along the way, you gained hands-on experience with configuring Hydra, creating wordlists, and understanding the syntax for launching brute force attacks against HTTP login forms.

Additionally, you learned about various defense mechanisms that can be implemented to mitigate the risk of successful brute force attacks, such as enforcing strong password policies, implementing account lockout mechanisms, enabling multi-factor authentication, using CAPTCHAs or puzzles, implementing IP throttling or blocking, and monitoring and logging.

By completing this lab, you have gained practical knowledge and experience in understanding and defending against brute force attacks, a crucial aspect of web application security.