Mozilla Monitor notifies you when a data breach occurs, making sure to provide you the right path to remove your information and keep you safe. Sometimes a website you don’t recognize can pop up. Here are several reasons why this can happen, along with steps to protect yourself.

Reasons why you could be in a breach for a site you never signed up for

• Third-party data aggregators: Some companies collect personal information from various sources, including public databases, social media, or other websites, and then share or sell that data to other companies.

If a data aggregator is breached, your information might show up in a breach notification even if you never signed up for that particular site.

• Combolists and credential stuffing attacks: Hackers often compile login credentials from various breaches into large lists, known as combolists. These lists are used in attacks like credential stuffing, where hackers try to use those credentials across different websites.

If your email or other information was exposed in an earlier breach, it could have ended up on one of these lists and be connected to other sites you’ve never visited.

• Account creation by someone else: It's possible that someone else signed up for a service using your email address, either by mistake or deliberately. For example, an old colleague, a friend, or even a service you didn’t authorize may have created an account with your email.
• Acquisitions or name changes: The website might have been acquired by another company, merged with a different service, or simply changed its name. This means the site involved in the breach could be a rebranded version of something you did sign up for, but no longer recognize.
• Old or forgotten accounts: Sometimes, a site you don’t recognize could actually be a service you signed up for a long time ago. With the frequency of name changes and rebranding efforts, it can be easy to forget about these older accounts.

What can I do to protect myself?

1. Double check: Carefully review the information and the website to ensure that the breach isn’t applicable to you. It’s possible one of the scenarios above applies and you want to be certain this isn’t something significant.
2. Review your passwords: If email or password details were exposed, you’ll want to review passwords in your collection to see if you are reusing passwords across multiple websites. This will reduce the likelihood of a bad actor gaining access to another account in the event this is an authentic breach. Remember to always use a unique, strong password that is not used for any other accounts.
3. Resecure important accounts: Perform security checkups on important websites such as email or banks. This could be as simple as just changing the passwords for those accounts or something more involved such as reviewing access history for unrecognized locations. You may need assistance from those websites to perform these actions, but you want to be sure these sensitive accounts are protected.
4. Be cautious: Be careful where you share your information. Supermarket loyalty programs, clothing chain email lists and newsletters, are just several of the many businesses that ask for details about you. Being selective of who and where you share your information is a proactive step to protect your data. Using email masking services such as Firefox Relay, protect you even further by providing disposable email addresses that forward to your true email inbox.
5. Disregard: If you’re certain this doesn’t apply to you, or the information isn’t relevant, simply resolve the alert on the dashboard. See Resolve breaches with Mozilla Monitor for details.

Related articles

• Monthly Monitor Report Email
• What to do after a data breach
• Mozilla Monitor - Frequently asked questions