Do you leave a lot of tabs open while you’re browsing the web? You might want to stop after reading this. The Better Business Bureau has issued a warning to consumers about a surge in the hacker activity known as “tabnapping.”

The attack works by taking a tab you have open in your browser but haven’t checked in a while and making it look like the log-in page for a popular site, like Gmail. When the user clicks back, they think they’ve been logged out of a site they were using and fill in their info, at which point they are directed back to the real site (which they were never really logged out of), and the hacker has now gained access to their login details.

The best way to prevent this from happening is to try and keep your open tabs to a minimum. Barring that however, if you find yourself unexpectedly having to re-log in to a website, look at the browser’s address bar before entering any of your information, and make sure that what is there matches the site you want to be using. If you aren’t sure, then close the tab and try heading to the site from the beginning again.