Online survey scams are most often propagated through social network and sharing websites, but occasionally users are "assaulted" directly through their smartphones.

Hoax-Slayer warns about a bogus offer of a $1000 Walmart gift card for free hitting mobile phone users via the following text message:

You've been selected for a free $1,000 Walmart Giftcard! Enter the code 'FREE' at [Link Removed] to get it now. Only 116 left! Text OUT to stop

Users who follow the link to the website and insert the code are redirected to another one where they are asked to complete a quiz or a survey, or to share their name and contact details in order to compete for the prize.

At the end of each quiz or survey, the users are asked to enter their mobile phone number in order to get the results. Unfortunately for those who don't spot the text written in very small letters below the "Submit" button, by doing so they are automatically subscribing to extremely pricey SMS services.

"Such services are often difficult to unsubscribe from and can quickly run up large phone bills or consume available phone credit. In other incarnations of the scam, users may be invited to download dubious toolbars, games or software that may harvest the user's personal information or browsing habits," he warns.

Also, any and all of the information shared with the sites can be used for targeting the users with additional spam or, at worse, to perpetrate identity theft or credit card fraud.

It's also worth to mention that no matter how many surveys the users complete, they are never getting the Walmart gift card that lured them into the scam in the first place.