Brute Force Attack: Types And Prevention in 2021

To understand what is a Brute Force attack, let’s get the basics right.

  1. What is Hacking?
  2. So What A Brute Force Attack Really Is
  3. Types Of Brute Force Attacks
  4. How To Prevent A Brute Force Attack
  5. What Tools are available to detect Brute Force Attacks

1. What is Hacking?

With the proliferation of IT in our daily lives, we tend to value the convenience that IT infrastructure offers more than the security around it. We tend to ignore the security that such systems offer or rather lack of it. Although  IT security is an important part in business transactions, it doesn’t deserve the attention it requires. It could be in part due to the obscurity of loopholes and vulnerabilities, you know, out of sight is out of mind. This introduces risks like hacking, identity theft, hijacking and many such serious cyber crimes.

Hacking is defined as an unauthorized entry into any system with the intention of causing harm or stealing valuable information. Hacking and other breaches in IT infrastructure has cost millions of dollars in revenue for many businesses and individuals alike. The hit that the business takes on its reputation is insurmountable. To guard against hacking, it is important to know the types of hacking and how it is perpetrated.

There are several types of hacking. One of them called Brute Force Attack is what we shall focus on, in this article.

2. So what Brute Force Attack really is.

Brute Force Attack is a cryptographic hack. Also known as Exhaustive Search, this kind of hack involves attempting several combinations for a password until one of them lets you in. The hacker could also attempt to guess the key which is derived from the password using a key derivation function. This is known as Exhaustive Key Search.

Brute force attacks may work for simple and short password breaking, but might not be an ideal choice for complicated and longer passwords. It will take a long time to work out all combinations for a longer password.  

3. Types of Brute Force Attacks

There are primarily 5 types of brute force attacks.

  • Simple Brute Force Attack

This kind of attack is based on logical guesses, rather than using a targeted software. This is typically used on weak passwords.

  • Dictionary Attack

This kind of attack relies on a script or hacking tool, using a dictionary list of common words and phrases in general use.

  • Hybrid Brute Force Attack

These attacks typically combine logical guesses with dictionary attacks to figure out passwords that use a combination of dictionary words and random characters.

  • Reverse Brute Force Attack

The reverse brute force attack, is exactly what the name implies, it takes a commonly used password and tries these passwords on millions of accounts until they find a match.

  • Credential Stuffing

Once a hacker has a working username and password, there is all the chance that the same credentials will work on many other online assets.

What are the tools that hackers employ for brute force attacks?

Popular tools that perpetrators of this crime use are listed below.

Aircrack-ng, John the Ripper, Rainbow Crack, L0phtCrack, Ophcrack, Hashcat, Dave Grohl, Ncrack, THC Hydra.

How are brute force attacks detected.

Brute force attacks on a system with either MS Windows or Linux installed, leave a trace of the unsuccessful attempts made. If you see a string of unsuccessful attempts to login in to the respective log files of Linux and Windows, you know your machine is under attack.

4. How to Prevent a Brute Force Attack.

There are many techniques to stop or prevent a brute force attack.

  • Since it is only the password that is attacked in this case, having a strong password policy will eliminate most of the risks related to such types of attacks. A strong password policy once created and deployed will ensure the login credentials created hence will be least susceptible to these attacks. Knowing that a password that is 8 characters long takes 5 hours to break and one with 9 characters takes 5 days to break, having longer passwords makes the job of the attacker really difficult. Servers and admins should require frequent password changes for all user accounts on the servers.
  • Since brute force attack depends heavily on innumerable attacks to get through, it would be a good idea to limit the number of failed login attempts. But you would have to tread carefully on this path. If you configure the system to disable the account after multiple login attempts, the attackers can easily take advantage and bring your setup down by forcing virtually all accounts to get disabled, provided they have access to a significant number of user accounts in their possession.
  • For Linux based systems, making the root user inaccessible via SSH will ensure. SSH is a tool used to remotely connect to a server in a secure way. Root user is the user account having the privilege for executing anything on the machine. With access to the root user gone, the attacker can do little or no damage.
  • Another method is to not use a default port. You could change the port number to any number, to minimize chances of unauthorized access.
  • Captcha has been a universal solution to fend off attackers of both DDOS and Brute Force.  Captcha has evolved over the years to include images as a means to identify bots or hacking scripts trying to mimic a user.
  • Another very trusted method is two factor authentication. In this method, the system requires the user to submit another level of authorization usually through a mobile phone or email.
  • Also suggested to mitigate Brute Force attacks are to use unique logins for different groups.  This is just increasing the complexity for the attacker, an additional layer of obscurity.

5. What Tools are available to detect Brute Force Attacks

All major internet security software suites offer this feature to red flag brute force attacks to the administrator. Tools like McAfee, Norton Internet Security, Kaspersky and many more will help you by alerting these brute force attempts so you secure your assets well enough. The tools also detect loop holes that could be exploited for brute force attacks and red flag these to the administrator.


Brute Force attacks can expose your invaluable corporate data including your business secrets and intellectual property to the ever increasing tribe of cyber criminals. Secure your assets with best practices followed in the industry and review security on a periodic basis.

So, have you made up your mind to make a career in Cyber Security? Visit our Master Certificate in Cyber Security (Red Team) for further help. It is the first program in offensive technologies in India and allows learners to practice in a real-time simulated ecosystem, that will give you an edge in this competitive world.


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