TabnabbingTabnabbing is a type of attack in which an intruder changes one of the inactive tabs that exist when a user opens his browser. The page that was on that tab is being changed into another one, often a fake cloned login-page of a website the user regularly visits. Because this person doesn't remember anymore whether he himself loaded that page or the hacker he can be tricked into entering his credentials and giving away this valuable information to the intruder. It could also show a message that the user needs to login within a certain period of time or be automatically logged off.
People need to be aware that this type of attack exists and that they preferrably better not leave too many tabs inactive for a longer period of time.