Brute Force - CheatSheet

👉 Overview

👀 What ?

Brute Force is a type of cyber attack in which an attacker tries all possible combinations of passwords or encryption keys until the correct one is found. The underlying concept is simple: try everything until something works.

🧐 Why ?

Understanding Brute Force is important because it is one of the most basic and commonly used attack methods in cyber security. It is used to crack encrypted data, gain unauthorized access to systems, and can be a significant threat if proper security measures are not in place. For anyone involved in network or system security, understanding how brute force attacks operate is crucial.

⛏️ How ?

Brute Force attacks can be performed manually or with the help of software tools designed for this purpose. These tools systematically attempt every possible combination of passwords or keys until the correct one is found. To protect against these attacks, strong passwords and encryption keys should be used, and systems should implement measures like account lockouts after a certain number of failed login attempts.

⏳ When ?

The use of Brute Force attacks began with the advent of computer systems and has been a persistent threat ever since. As long as there are systems and data to be protected, there will be attempts to break into them, making the understanding and prevention of brute force attacks a timeless necessity.

⚙️ Technical Explanations

A brute force attack, at its essence, is a method of trial and error. The attacker systematically checks all potential combinations of keys or passwords until they find the correct one. The time required to crack a password via brute force is dependent on the complexity of the password, which is determined by its length, the complexity of its characters, and the randomness of its composition.

Brute force attacks can range from simple to sophisticated. In a simple brute force attack, the attacker may simply try out different passwords. On the other hand, more complex brute force attacks employ additional techniques to avoid detection or expedite the process. For instance, distributed attacks involve the attacker using multiple machines to carry out the attack, thereby speeding up the process and making detection more difficult.

Another complex method is the rainbow table attack. In such attacks, the attacker pre-computes a list, known as a rainbow table, of potential hashes for possible password combinations. This way, they can simply look up the hash of a password in the rainbow table instead of having to compute it during the attack, which significantly speeds up the process.

To safeguard against these types of attacks, it's recommended to use strong, complex passwords and implement security measures such as account lockouts or delays following a certain number of incorrect attempts. Using multi-factor authentication can also provide an additional layer of security. Additionally, monitoring network traffic for repeated login attempts from the same IP address can help detect potential brute force attacks.

An example of a simple brute force attack could be cracking a zip file password. Here's how it can be done using a tool like John the Ripper, a popular password cracking tool:

1. Step 1 - Install John the Ripper: You can download and install the software from the official site. For Linux, you can use the following command:

   sudo apt-get install john
   
   

2. Step 2 - Create a password-protected zip file: For this illustration, let's assume we have a file named secret.zip that is password-protected.

3. Step 3 - Convert the zip file to a format John the Ripper can understand: This can be done using the zip2john command, which is part of the John the Ripper tool suite:

   zip2john secret.zip > secret.hash
   
   

   This command creates a new file, secret.hash, which contains the hash of the zip file's password.

4. Step 4 - Use John the Ripper to crack the password: The password can be cracked using the following command:

   john secret.hash
   
   

   John the Ripper will then start trying all possible password combinations. The time it takes will depend on the complexity of the password.

5. Step 5 - Show the cracked password: Once the password has been found, you can display it using the following command:

   john --show secret.hash
   
   

   This will display the password for the secret.zip file.

6. Step 6 - Use the cracked password: With the cracked password, you can now open the secret.zip file.

This is a simple illustration of a brute force attack. It's important to note that such an attack should only be performed for ethical purposes, such as recovering a forgotten password. Unauthorized hacking is illegal and unethical. Also, to protect against such attacks, use strong, complex passwords, and consider implementing additional security measures such as multi-factor authentication.

🖇️ Références