Hundreds of thousands of Facebook users are falling victim to so-called "clickjacking" attacks, warn web security labs.
Facebook members see links to subjects such as "World Cup 2010 in HD" or "Justin Bieber's phone number" that their friends appear to have "liked".
Clicking the link tricks users into recommending the site on Facebook too.
Security experts say the scam currently has no malicious intent but could be adapted to deliver malware.
The link generally takes the user through to a page containing an instruction, such as asking them to click a button to confirm that they are over 18.
However, wherever they click on the page it adds a link to their own Facebook profile saying they have also "liked" the site.
source: news.bbc.co.uk/1/hi/technology/10224434.stm