Firefox to Display Warning if You Visit a Site That's Been Breached

The Firefox browser will soon issue a warning if you visit a site that recently suffered a data breach.

The warnings will appear on Firefox's desktop browser as pop-up notifications that tell you how many accounts were compromised in the breach.

The same pop-up will show you a link to Firefox Monitor, a free service that lets you check whether any of your internet accounts were ensnared in a data breach. Simply click the link and type in your email address to view whether your accounts were hit.

The new function will roll out to Firefox in the coming weeks, at a time when users are demanding more security and privacy features, Mozilla said. "Data breaches are common for online services," company privacy engineer Luke Crouch wrote in a blog post. "Some online services discover, mitigate, and disclose breaches quickly. Others go undetected for years." Making matters worse is that most people simply don't know that a breach has affected them, he added.

The pop-up warnings from Firefox will hopefully change this. It'll also give users a chance to secure their affected accounts—before hackers have a chance to take advantage of the situation. For instance, when a breach occurs, you should change the password on the affected account and enable two-factor authentication if available.

It's also good idea to make sure all your internet accounts are secured with unique passwords. Hackers like to check whether their victims re-used any exposed passwords on other internet accounts.

Mozilla built its notification system using data from security researcher Troy Hunt, who maintains an active library of all the latest data breaches at Haveibeenpawned. His site also lets you type in your email address to check whether it's been affected in a data breach.

So how often will you see these alerts from Firefox? "This alert will appear at most once per site and only for data breaches reported in the previous twelve months," the company said.

You'll see an additional alert if the website you visit experienced another reported breach within the last two months. Mozilla settled on this time-frame to avoid stoking unnecessary fear. "We don't want to alarm users or to create noise by triggering alerts for sites that have long since taken significant steps to protect their users. That noise could decrease the value and usability of an important security feature," Crouch said.

If you get annoyed with the alerts, you can turn them off. Click the drop-down arrow on the pop-up notification, and choose "never show Firefox Monitor alerts."

But if you'd like to know more about the latest data breaches and whether you're affected, sign up for email alerts through the Firefox Monitor service or Haveibeenpawned. They'll notify you if your data crops up in another publicly known breach. You can also read our tips on staying safe online here.