How to Prevent Brute Force Attacks?

Learn what are brute force attacks, their different types, and how to prevent brute force attacks in general. We will also cover the best solutions you can use to defend against them.

Brute force attack is a trial-and-error way of figuring out what your sensitive keys, login credentials, and passwords are. The attacker will use every automation tool possible to systematically try out every possible password/login combination until eventually the correct one is found.

In this guide, we will talk about how to safeguard against brute force attacks. You will also learn how to prevent brute force attacks in the process.

Why Preventing Brute Force Attacks is Important?

Brute force attacks are unpredictable since you don't know when someone crashes into your account and steals your sensitive data. You can lose your bank and credit card details, identity data, and even healthcare information.

And guess what? When attackers have all that info, they can sell it on the dark web. They don't care about you as an individual or what happens later. Your business will get majorly impact and customers can permanently lose their trust in your mission. The LastPass breach was a stark reminder of what can happen when brute force attacks aren't prevented and get ignored. Brute force attacks can also be used to steal your local files and can consume significant CPU memory and bandwidth.

It also impacts the performance of your targeted systems and can make it difficult for other users to access resources, if they get locked out. You can also end up spreading malware and have to pay heavy fines for violating any data protection laws due to sensitive data losses.

How Do Brute Force Attacks Work?

A brute force attack works by selecting a good target. The attacker will be careful and decide on whether they are going for a specific web service login page, encrypted files, API endpoints or individual user accounts. Once they have decided, they are going to use various techniques to generate potential passwords.

A simple brute force attack will use software to try out every single combination of letters, numbers and symbols like AA, AB, AC etc. It's very high in compute but given enough time is guaranteed to work eventually.

Dictionary attacks will use pre-compiled lists of common phrases and words that had previously breached passwords. These are also known as word lists and dictionary attacks make up a fast yet simple part of brute force attempts. Then we have credential stuffing where the attacker has a list of stolen usernames and passwords from different sites and breaches.

They can just try reusing those login credentials to see if they work. Other than these techniques or tactics, the attacker can also use automated software tools like bots and scripts to submit their guesses at incredible speeds. They can send large volumes of login requests and move immediately to next guesses across sequences.

Sometimes attackers might use services that can use AI and machine learning to solve captures which are intended to stop automated login attempts. The main idea is that attackers will stop at nothing until they crack and take over your account. So they will continue using a combination of tactics until they eventually get the right hits. Once a brute force attack is successful, they are going to move deeper and more laterally across your networks and perform malicious actions.

Warning Signs of a Brute Force Attack

The warning signs of brute force attacks are pretty clear. Here's what you should notice:

• High volume of failed login attempts and logins from unexpected geographic locations, especially within short time frames. Repeated account lockouts and a high number of failed attempt limits, is also another indicator.
• We also have suspicious IP activities like attempting to access a single account from different IP addresses. Unusual login times are another indicator, especially outside regular business hours.
• You also want to watch out for high server resource consumption. If you take a look at your system logs, you might notice signs of repetitive error messages and attempts to log into non-existent usernames.
• If you notice any suspicious login attempts, you should check your system logs to see if there are any logins to non-existent usernames. If you notice any successful logins after repeated failures, then that's a sign that the attacker has successfully found the correct credentials.

How to Prevent Brute Force Attacks: Best Practices

This is the first and most important thing you should be aware of. There is no 100% foolproof way to prevent a brute force attack but that doesn't mean you can stop them.

You can layer your protection which is better than having none and here are some of the best ways on how to prevent brute force attacks:

1. Set Stronger Passwords

Use strong and unique passwords. Don't make your passwords easily guessable or use common phrases which are too well known or popular. Make your passwords at least a mix of upper and lower case characters, numbers and special letters. Make them a minimum 8 characters long.

Also use a password manager to keep track of passwords. Check global databases of most commonly used passwords and avoid them because there's a high chance that they've already been reused or hacked. Implement policies to reject weak passwords and enforce users to change their passwords frequently. This is where password managers come in and yes, you might think that password managers can be hijacked but it's not like that. They are still safe and work just as good.

2. Set up multi-factor authentication

This is non-negotiable and it will add an extra layer of security to all your accounts. Having multiple authentication factors can block out adversaries because if they get in through one way, the other ways will stop them.

Your authentication factors can be a mix of biometrics, screen locks, security tokens, and so many other things.

3. Do Account Monitoring and Activity Tracking

Also, keep track of your account activities such as the number of failed login attempts and IP addresses and locations. You want to know who is logging in from where, and regular monitoring can help you identify and respond to brute force attacks before they happen. You can stop brute force attacks in their tracks by using regular monitoring tools, and it's one of the best ways to prevent them.

4. Use Rate Limiting

You should also use rate limiting, which can limit the number of login attempts per session within a time period. It locks down accounts after a certain number of attempts have been made. This makes it harder for adversaries to guess passwords and break in.

5. No Using Default Login Credentials

Don't use default usernames and passwords. This is a rookie mistake but many people still do this which is why we are pointing it out. Many administrative interfaces, VPNs and RDP connections also use default credentials so watch out for those as well because they can serve as potential entry points.

6. Fix Outdated Software and Unpatched Vulnerabilities

Don't use outdated software and watch out for unpatched vulnerabilities because attackers can exploit them. This applies to both your software and hardware firmware.

7. Don’t Store Passwords in Plaintext Files

Don't store your passwords in plain text files or use weak hashing because if a database is breached, attackers can use rainbow tables or crack stuff offline to quickly uncover your plain text. 

8. Educate Your Employees

Teach your employees good password hygiene practices and how to recognize phishing scams which can lure them and steal credentials. They should also be aware of the importance of reporting suspicious activities and know what to watch out for.

Common Mistakes That Increase Brute Force Risk

If you don't know yet how to stop brute force attacks, then you should start by being aware of the common mistakes you can possibly make. Here is what not to do to prevent increasing your brute force risks:

Don’t Use Easy Passwords

Don't use short passwords, common words and easily guessable character combinations. No personal information like names, birthdays, phone numbers and easy to guess everyday details. Attackers can just pull out your social media and base brute force attacks off of them and it takes them just a matter of hours or minutes.

Don’t Reuse Existing Passwords Elsewhere

Using the same password is another no-go. Don't use the same set of credentials across different accounts, websites and services online, especially banking and email. Set your apps up properly and configure them so that they don't allow an unlimited or high volume of failed login attempts. This can prevent attackers from experimenting with millions of password combinations and automatically trigger protective mechanisms.

Don’t Ignore MFA

Don't neglect multi-factor authentication. Single sign-on is no longer effective these days because attackers can steal your phone numbers, fingerprints and other passwords. You need multiple authentication factors for a good reason.

How SentinelOne Helps Defend Against Brute Force Attacks

To prevent brute force attacks and protect against them, you will need to monitor for indicators and signs of brute force attacks. One of the best ways you can do this is to use SentinelOne’s AI SIEM solution.  SentinelOne's AI SIEM solution is built on its Singularity™ Data Lake. It can help you rebuild your security operations by granting you real-time AI powered protection for the entire enterprise. You can move into a cloud native AI SIEM and take advantage of its limitless scalability and endless data retention. You can also speed up your workflows with SentinelOne's hyper automation. It protects your endpoints, clouds, networks, identities, emails and more. You can also stream your data for real-time detection and get greater visibility for investigations.

SentinelOne can protect against brute force attacks via its AI-powered behavioral analysis and Singularity™ Identity modules. It can detect and stop brute force attack patterns in real time and for strong authentication and also brings to the table effective deception technology.

You can monitor user and system behaviors like unusual volumes of failed login attempts or logins from weird or unknown geographic locations. Singularity™ Identity can help you protect against credential-based attacks by continuously assessing your identity systems.

You can prevent automatic account lockouts and apply rate limiting. You can also enforce multi-factor authentication and add additional verification factors like time-based codes and biometrics beyond just simple passwords.

SentinelOne's deception technology can plant deceptive lures like bogus network shares within your environments. This can fool attackers into interacting with decoys and trigger high-fidelity alerts automatically, thus revealing their presence and intent. You can also misdirect attackers away from your actual sensitive assets.

SentinelOne can also autonomously respond by and isolate your affected endpoints. It can terminate malicious processes, block attackers' IP addresses, and even roll back unauthorized changes to restore systems back to their pre-infected states. All this is done without human intervention.

Conclusion

So now we've pretty much covered everything you need to know about how to prevent brute force attacks. All we can say is good luck, be vigilant and don't make your passwords too easy to guess.

You now know how to prevent a brute force attack and it's time to tell your employees to be on their toes and not take password security for granted. If you need to reach out to SentinelOne for further assistance, contact us. We are happy to help.

FAQs

What is a brute force attack?

A brute force attack is when someone tries thousands of password combinations to gain access to your accounts or systems. The attacker uses automated tools to guess passwords repeatedly until they get one right. These attacks target everything from email accounts to network logins. They're straightforward and don't require fancy exploits - just time and computing power. If your password is weak or short, the attacker will get in faster. Brute force attacks happen constantly across the internet, and any account without strong protections is at risk.

How can organizations prevent brute force attacks?

Start by enforcing strong password policies, your passwords should be long and complex. Set up multi-factor authentication so even if someone guesses the password, they can't log in without a second verification. Limit the number of login attempts before an account locks temporarily. Monitor your network for unusual login patterns and failed access attempts. Use CAPTCHA on login pages to slow down automated attacks. Keep all systems patched and updated. Train your employees to use unique, strong passwords and not reuse them across different services.

Can CAPTCHA help stop brute force attacks?

Yes, CAPTCHA can help slow down brute force attacks. It forces an attacker to solve visual or puzzle challenges instead of just throwing passwords at your login page automatically. However, CAPTCHA isn't a complete solution by itself. Sophisticated attackers can use CAPTCHA-solving services or other workarounds. You should combine CAPTCHA with other defenses like rate limiting, multi-factor authentication, and account lockouts. The goal is to make brute force attacks so time-consuming and difficult that attackers move on to easier targets.

How does password length affect brute force resistance?

Longer passwords make brute force attacks exponentially harder. A 6-character password can be cracked in hours. An 8-character password takes days or weeks. A 12-character password takes months or years of computing effort. Each additional character multiplies the combinations an attacker must try. If you combine length with complexity—mixing letters, numbers, and symbols—you make the attacker's job much worse. A 16-character password is dramatically more secure than an 8-character one. Length is one of the most effective defenses you have against brute force attacks.

What tools detect brute force attacks?

You can use intrusion detection systems to watch for repeated failed login attempts. Security information and event management platforms monitor your logs and flag suspicious patterns. SentinelOne Singularity XDR can detect brute force activity across your systems. Firewalls with built-in protections can block repeated connection attempts from the same source. You should also check your authentication logs and network traffic for signs of attack. Anti-malware solutions combined with continuous monitoring help catch brute force attempts before they succeed.

How to Detect Brute Force Attempts in Real Time?

Monitor your authentication logs continuously and look for multiple failed login attempts from the same IP address or user account. Set up alerts that trigger when login failures exceed a certain number in a short timeframe. Watch your network traffic for patterns that indicate automated login attempts. Configure your firewall and access controls to log all authentication events. Use security tools that analyze logs in real time rather than after the fact. The faster you detect an attack, the faster you can block the attacker and protect your accounts.