Microsoft researchers have analyzed this particular scheme
Security experts from Microsoft have come across a Facebook scam that advertises free $250 Costco gift cards.It all starts like a classic survey scam. The user is presented with a free offer for Costco Wholesale Cash Cards which he can win if he shares the advertisement on Facebook and posts a comment.
In the second phase, internauts are promised a $500 gift card in return for some information such as name, address, birth date, zip code, email address, and phone number.
At this point, a fine print displayed on the bottom of the page reveals that by submitting the details, customers are actually authorizing auto-dialed phone calls and SMSs to the entered number.
However, the scheme doesn’t end here. Victims are not only requested to complete various surveys, but they’re also asked to install a “coupon app” which in reality is a hidden toolbar which monitors browsing habits. Microsoft has identified this piece of software as BrowserModifier:Win32/BSaving.
It’s uncertain what the information is collected for, but judging by the shady marketing that's involved, it’s certainly not something that would benefit users.