You're not that far off. If you took the Alexa Top 100k sites and display some kind of indication whenever a page isn't on that list you would be able to stop t

You're not that far off. If you took the Alexa Top 100k sites and display some kind of indication whenever a page isn't on that list you would be able to stop the most obvious phishing attempts. Google has a Safe Browsing Extension which, as its first steps, checks the 15k most common sites or so. If you tailor these lists to specific countries I'd wager you can get away with even fewer entries. There's other tricks that scammers pull though, like compromising legitimate domains with a certain reputation and then adding their scammy subdomains, but that's a lot harder to pull off than just registering 100 free domains everyday and hoping one sticks.