Savvy Internet users know that downloading unsolicited computer programs is one of the most dangerous things you can do online. It puts you at great risk for a virus or another time bomb from a hacker.

But even some sophisticated surfers could get taken in by a sneaky new attack in which criminals create fake YouTube pages - dead-on replicas of the real site - to push their malicious software and make it look like it’s safe stuff coming from a trusted source.

A program circulating online helps hackers build those fake pages. Users who follow an e-mail pointing them to one of the pages would see an error message that claims the video they want won’t play without installing new software first. That error message includes a link the hacker has provided to a malicious program, which delivers a virus.

Even worse: once the computer is infected, it’s simple for the hacker to silently redirect the victims to a real YouTube page to see videos they were hoping to see - and hide the crime.