Brute Force Attacks Explained: How They Work And How To Stop Them On Your Servers

Cybersecurity teams and hosting admins don’t lose sleep over “fancy” hacks as much as you might think.
Most real incidents still come down to the same boring thing: someone guessed or stole a password.
If your internet‑facing servers and web apps can be hit from the public internet, brute force attacks are one of the cheapest ways for attackers to get in.
This guide walks through how brute force attacks work, how to spot them early, and what you can do to make them much harder and more expensive for attackers.

Why brute force attacks still work

Compromising login credentials is the main goal of many modern cyber‑attacks.
Verizon’s 2025 Data Breach Investigations Report says around 88% of web application attacks in the last year involved stolen credentials. That’s a polite way of saying: passwords are still a huge weak point.

Attackers love brute force attacks because:

• They’re simple to automate.

• They don’t require some rare zero‑day.

• They often work against weak passwords and poorly configured servers.

If your users reuse passwords, pick “Summer2025!” a lot, or if your hosting setup doesn’t limit login attempts, brute force is basically an open invitation.

What is a brute force attack (in plain language)?

Imagine someone trying to unlock your front door by quickly running through every key on the planet.
A brute force attack is that, but for passwords and logins.

An attacker points a tool at your login page, VPN, SSH, email service, or control panel.
That tool:

• Tries password after password at machine speed.

• Watches for one successful response: “Login OK”.

• Moves quietly so it blends in with normal traffic (at least at first).

The more computing power the attacker has, and the weaker the passwords, the faster they can break in.

The goal is always the same: guess the right credentials and get unauthorized access to something valuable—databases, mailboxes, control panels, cloud dashboards, or servers.

Common types of brute force attacks

Not every brute force attack looks the same. The idea is the same, but the strategy changes a bit.

1. Simple brute force

This is the pure “try everything” method.

• The tool cycles through every possible character combination.

• It starts with short, simple passwords and works up to longer ones.

• It’s slow against strong, long passwords but brutally effective when people use things like “qwerty123”.

If your security controls don’t limit or slow down login attempts, this can run for hours or days without anyone noticing.

2. Dictionary attack

Here, the attacker gets a head start instead of trying every combination.

They use a “dictionary” of likely passwords:

• Common passwords (“Password123”, “Welcome1”, “Admin2024”).

• Variants like “CompanyName2025!”.

• Real leaked passwords from previous data breaches.

The tool works through that list rather than guessing randomly.
If your users like easy-to-remember passwords, dictionary attacks work very well.

3. Reverse brute force attack

Reverse attacks flip the usual pattern.

Instead of:

• Many passwords → one user

They try:

• One common password → many users

Example: the attacker tries “Password123!” against every username they can find in your organization.

This works because:

• People copy each other’s passwords.

• Default or temporary passwords often stay in place longer than they should.

If someone, somewhere, kept that weak password, the attacker gets in.

4. Hybrid attack

Hybrid attacks mix dictionary and simple brute force ideas.

The attacker:

• Starts with a dictionary (common passwords, leaked ones, company-related words).

• Automatically adds numbers, years, and special characters before/after those words.

So “spring” becomes:

• spring2025!

• Spring_25

• spring#01

If users think, “I’m safe, I added an exclamation mark,” hybrid attacks are built for them.

A real-world brute force case: the T‑Mobile breach

Brute force isn’t just theory. It has already hit big names.

In August 2021, T‑Mobile, one of the largest wireless carriers in the US, suffered a major breach traced back to a brute force attack.
The result:

• Around 37 million customers impacted.

• Sensitive data exposed: Social Security numbers, driver’s license details, and other personal records.

The lesson is simple: even large, well‑resourced companies can be taken down by weak credentials and exposed login surfaces.

Passwords were stored as hashes, but that doesn’t magically make brute force disappear.
Attackers can still hammer away at login endpoints or hash values until they find a match.

How to detect a brute force attack in progress

Catching brute force early is a big win.
These attacks rarely arrive “perfectly clean”—they leave patterns in your logs.

Here’s what to watch for.

1. Unusual spikes in failed logins

Red flags in your authentication logs:

• Dozens or hundreds of failed attempts over a short period.

• Many failures from the same IP address or IP range.

• Repeated failures on the same user account.

If your SIEM or log system starts showing big clusters of failed logins, especially on sensitive services (VPN, SSH, RDP, admin portals), assume someone is testing the door.

2. Logins from unusual locations

Brute force tools often run on compromised servers or large botnets spread around the world.

Warning signs:

• Login attempts from regions where you have no staff, customers, or servers.

• One user “logging in” from two countries within minutes.

• A sudden wave of attempts from cloud provider IP ranges you don’t use.

Geo‑based alerts aren’t perfect, but they’re helpful.

3. Repeated attempts with common usernames

Attackers love predictable usernames:

• admin

• test

• user

• user1

• Service accounts (backup, deploy, serviceuser)

If you see a lot of failed attempts against these common names, especially paired with simple passwords, you may be facing a reverse brute force attempt.

4. High authentication traffic at odd hours

Most people sleep. Attack scripts do not.

Suspicious patterns:

• Huge login spikes during nights and weekends.

• Authentication traffic that suddenly doubles or triples at off‑peak times.

• Consistent high login volume that doesn’t match business needs.

If nobody is doing a penetration test or load test, investigate.

5. Frequent account lockouts

Account lockouts can be a safety net, but they’re also an alarm bell.

Watch for:

• Many users across departments being locked out in a short time.

• Critical admin accounts repeatedly hitting lockout thresholds.

• Lockouts where users insist they weren’t even trying to log in.

That pattern often means someone is hammering passwords behind the scenes.

How to prevent brute force attacks

There’s no single magic switch, but a few layered controls make brute force attacks much harder, slower, and less profitable.

Think of it as making the attacker’s life miserable.

1. Longer, stronger passwords (or passphrases)

Short passwords are easy targets.
Long passphrases are harder to crack and easier for humans to remember.

Good patterns:

• Use at least 14–20 characters.

• Combine random words into a phrase: apple-bridge-cactus-traffic.

• Add a few less common symbols and numbers.

Each extra character makes brute force more expensive in time and computing power.
If you run identity systems, enforce minimum length and block obviously weak or previously compromised passwords.

2. Use multi‑factor authentication (MFA) everywhere you can

Assume passwords will leak sooner or later. MFA is your backup.

MFA adds a second step:

• One‑time code in an app or text.

• Hardware security key.

• Push notification to confirm logins.

Even if an attacker guesses the password, they’re stuck without that second factor.
Prioritize MFA for:

• Admin and root accounts.

• VPN and remote access.

• Email.

• Management consoles and hosting control panels.

3. Limit and slow down login attempts

Rate limiting and lockout policies don’t sound exciting, but they’re powerful against brute force.

Consider:

• Locking accounts for a short period after several failed attempts.

• Adding a delay (a few seconds) between failed attempts.

• Using CAPTCHAs after multiple failures from the same IP.

• Blocking IPs or IP ranges that repeatedly trigger failures.

The goal is to make automated guessing slow and noisy, not smooth and quiet.

4. Monitor logs and set up smart alerts

Your logs already know a lot about brute force attempts. You just need to listen.

Practical steps:

• Centralize logs (VPN, web app, SSH, RDP, control panels).

• Set alerts for:

  • Rapid failed logins.

  • Unusual geographic locations.

  • Repeated attempts against the same account.

• Review alerts regularly, not just when something breaks.

Even a simple dashboard that shows “top failed usernames” and “top IPs by failures” can reveal ongoing credential attacks.

5. Harden your hosting and network edges

Brute force doesn’t only hit the application. It also hits the infrastructure layer.

Things you can do:

• Put sensitive services (SSH, RDP, admin panels) behind VPNs or private networks.

• Use firewalls and security groups to limit who can even see your login endpoints.

• Disable direct internet access to high‑impact admin interfaces.

• Move legacy or unused login paths off the public internet.

Your choice of hosting provider matters too. Some providers help you with network‑level protection, clean IP ranges, and security‑first configurations by default.

👉 Discover how GTHost gives your servers a stronger first line of defense against brute force attacks and other noisy login abuse

When your infrastructure platform already cares about performance and security, your own controls sit on a more stable, easier‑to‑manage foundation.

6. Educate users without scaring them

You don’t need a three‑hour security lecture. Just make a few habits normal:

• Don’t reuse passwords between work and personal accounts.

• Use password managers to generate and store strong passwords.

• Report strange login prompts or unexpected MFA requests immediately.

People are part of your defense, not just your risk.

A quick brute force defense checklist

If you manage servers, web apps, or any kind of hosting environment, aim for this baseline:

• Strong, long passwords or passphrases enforced by policy.

• MFA on all critical systems and remote access.

• Login rate limiting, lockout, and/or CAPTCHA after repeated failures.

• Centralized logging with alerts for suspicious login patterns.

• Restricted access to admin panels (VPN, firewalls, private networks).

• Regular reviews of weak accounts and old service logins.

You won’t be “unhackable,” but brute force attackers will move on to an easier target.

FAQs about brute force attacks

What is a brute force attack?

A brute force attack is when an attacker uses automated tools to rapidly guess passwords or encryption keys by trying many combinations until one works. It’s simple, noisy, and still very common against web apps, SSH, VPNs, email, and control panels.

How long does it take to brute force a password?

It depends on:

• Password length and complexity.

• How many guesses per second the attacker can make.

• How strict your login rate limits and lockouts are.

A short, simple password might be guessed in seconds or minutes. A long, random passphrase with proper rate limiting can take years or be practically impossible.

Is brute forcing illegal?

Yes. Trying to access systems you don’t own or don’t have clear permission to test is illegal in most countries. Security teams only perform controlled testing against systems they are authorized to assess.

How is brute force different from credential stuffing?

• Brute force: guesses many possible passwords for an account (or many accounts).

• Credential stuffing: reuses real username/password pairs stolen from other websites or breaches.

Both target login systems, but brute force guesses; credential stuffing replays known credentials.

Can my hosting provider help stop brute force attacks?

Yes, a good hosting provider or dedicated server platform can help a lot:

• Network‑level blocking and firewalls.

• Clean IP reputation and DDoS protection.

• Easy tools to restrict access to admin services.

• Fast, stable infrastructure so security controls don’t slow everything down.

Choosing a security‑aware provider and then adding your own controls on top is usually easier than building everything from scratch on a weak platform.

Conclusion

Brute force attacks aren’t glamorous, but they’re still one of the easiest ways for attackers to turn weak passwords and exposed login pages into real breaches. Strong passphrases, MFA, rate limiting, good monitoring, and tighter network controls all work together to make these attacks slow, noisy, and unattractive.

If you run internet‑facing servers or host critical apps, your infrastructure choice is part of your defense plan. That’s also why GTHost is suitable for securing internet‑facing servers against brute force attacks: combining solid hosting performance with a security‑first mindset gives you a faster, more stable, and more controllable base to build on.