Leaked passwords: How to find out if someone has obtained your data

You might feel that by using strong and unique passwords, you are safe. However, the internet operates differently than most people imagine. Practically every week a new data breach emerges, releasing login credentials from compromised services onto the internet. These often end up in vast databases of leaked passwords, freely circulating among hackers and regular users alike. It's not a human error, but a problem with compromised websites and applications where we log in.

All it takes is for one of them to be compromised, and your login credentials might end up somewhere they definitely don't belong. That's why it makes sense to regularly perform a password check. It will help you determine if your credentials are among the leaked passwords, allowing you to act before consequences arise.

In the article, we'll explain why having just a strong password isn't enough, how databases with leaked credentials work, how to safely verify your accounts, and how to protect yourself moving forward.

Why a strong password isn't enough

A strong password is a great start, but it alone doesn't cover everything. More often than guessing passwords, attackers obtain login credentials by breaching services. When data is leaked from a service, parts of these records end up among leaked passwords and continue to circulate on the network.

The problem intensifies as these files are combined and traded. Attackers compare them with other breaches, look for matches, and automatically test combinations of names plus passwords across hundreds of websites. This tactic is called credential stuffing by security experts and works because people repeat passwords or only slightly modify a basic combination.

The simple rule is: password strength doesn't guarantee safety if it has already been exposed elsewhere. Therefore, it's necessary to regularly check if your credentials are being sold or are circulating in leak databases. This information allows you to act promptly and prevent further damages.

How breached password databases work

When a data breach occurs from a service, attackers often combine the obtained data with other leaks to create extensive databases. These contain billions of emails, usernames, and hashed passwords from various years. Often, it's a combination of many smaller breaches merged over time into a single massive file.

To manage such a vast amount of data, records are tagged with the source and date of the breach. Attackers use these files for massive, automated login tests, methodically trying stored pairs of emails plus passwords on hundreds or thousands of websites. If you use the same password in multiple places, a single match is often enough for the attacker to access your other accounts.

But similar databases are also utilized by security experts. They use hash comparisons of passwords, allowing data to be compared without revealing the actual content. This enables the creation of secure tools that help users determine if their information has been leaked without risking misuse.

How to perform a secure password check

If you want to find out if your information has ever leaked, the most reliable method is to use the Have I Been Pwned service. It is one of the most trusted projects in the field of online security, collecting data from thousands of verified breaches.

Using it is simple. Open the website haveibeenpwned.com, enter your email, and confirm the search. In a few seconds, the result will appear. If the system finds no matches, a green message will indicate your account hasn't been recorded in any known breach. Conversely, if a match is found, you will see a list of services involved in the breach and the approximate date it occurred. You can also subscribe to notifications that inform you about new incidents.

Other options include integrated tools in web browsers. Google Chrome offers the Password Checkup service, Mozilla Firefox uses the Firefox Monitor system, and Microsoft Edge includes Password Monitor. All these features can automatically monitor saved passwords and alert you if they appear among leaked ones. The advantage is that the check is carried out directly within the browser and doesn't need to be run manually.

If you want more control over your login credentials, consider integrating the check with a password manager. Tools like 1Password, Dashlane, or LastPass work as a personal vault, securely storing all passwords and automatically filling them in. They also allow generating new, strong, and unique passwords for each account, so you no longer need to remember them and practically don't even need to know them since the application fills them in for you.

Features like Watchtower in 1Password, Dark Web Monitoring in LastPass, or Dark Web Insights in Dashlane use encrypted comparisons with leaked password databases and notify you if your details appear in a new breach. This way, you have an overview of all accounts in one place and the assurance that you can respond to potential issues immediately.

When you find out your data has leaked

Finding out your account appears in a database of leaked passwords is not necessarily a reason to panic. It means it was part of a data breach at some point in the past, not necessarily that someone is currently misusing it. The important thing is to remain calm and quickly take steps to minimize the risk.

1. Change the password on the compromised account.

Use an entirely new and unique password that you've never used elsewhere. If you used similar combinations across multiple services, change those as well. This will prevent exposed credentials from being reused.

2. Check recent logins.

Look to see if someone unauthorized has accessed your account recently. Gmail, Microsoft, Facebook, and other services allow you to view login histories and active devices. If anything suspicious appears, log out of all sessions immediately and log back in with a new password.

3. Enable two-factor authentication.

Besides the password, you'll enter a second verification code sent to an app or phone. Even if someone obtains your credentials, they cannot access your account without the second factor. Two-factor authentication is the most effective way to protect against further leaks today.

4. Verify other accounts.

Attackers often test the same email and password combinations on other websites. Conduct a new password check and ensure no other account is threatened. If you use a password manager, you can manage all your credentials in one place and receive notifications for any new breach.

5. Learn for the future.

A data breach isn't the end of the world, but a warning. React quickly, monitor your account security, and set up a system that will protect you in the future.

How to protect yourself moving forward

Cybersecurity isn't a one-time action, but rather a long-term habit. After a password check, you should also consider how to prevent similar situations in the future. The foundation is to stay informed about your accounts, maintain them regularly, and act before problems arise.

1. Categorize your accounts according to importance.

An email account used for logging in everywhere holds different significance than an account at an online store where you shop once a year. For the most important ones, use unique login credentials and two-factor authentication.

2. Set reminders.

Just like changing Wi-Fi passwords or PIN codes, it's worthwhile to periodically perform a quick account audit. Check if you're using old or similar login credentials anywhere and if your password manager reports any warnings about leaked passwords.

3. Be cautious about where you click.

Phishing emails are increasingly common. Never click on links requesting you to log in, even if they appear legitimate. Always manually log in through the official website or app.

4. Update devices and software.

Many attacks leverage vulnerabilities in outdated systems. Automatic updates are an easy way to protect yourself effortlessly.

5. Educate yourself and others.

Safe behavior online should be as natural as locking your apartment. Share these habits with those around you. The more people adhere to them, the lower the chance someone in your circles will inadvertently contribute to a data breach.

Check your accounts today

Data breaches are a reality of today's internet. While they can't be completely prevented, you can control how they may impact you. Simply check your accounts from time to time, address weak spots, and keep informed. Each such step increases the chance that even if your data ever leaks, it remains under your control.