Facebook users are being warned to steer clear of messages purporting to offer £500 vouchers for Asda.
Over the last two weeks, such messages have been sweeping the site, apparently posted by users' friends. But, says Asda on its Facebook page, "This is nothing to do with us and may be an attempt to capture your personal information."
Anyone clicking on the link finds themselves on a web page adorned with snowmen, which says there's a limited number of vouchers available and suggests that time is running out. It asks people to share the page and add a comment - which, naturally, spreads the scam still further.
Users are then asked to fill in an online survey: the real point of the exercise. Such surveys earn the scammers commission, often by tricking the user into receiving - and paying highly for - premium rate texts. They also net the scammers valuable personal information that can be used by marketers, or even hackers and identity thieves.
"Of course, it's not true that ASDA is giving away £500 shopping vouchers in what will be one of the busiest times of the year for the store. Just as it wasn't true when earlier this year a very similar scam spread claiming that CostCo was offering $500 shopping vouchers," says computer security expert Graham Cluley.
"Always be careful what you believe, and what you click on, on Facebook. Sadly, you cannot rely upon Facebook to properly police the scams which often spread across its site."
Last year, premium rate regulator PhonePayPlus fined two companies a total of £450,000 for similar scams, which purported to offer gift cards for several retailers including Tesco and Asda. Nearly 90,000 people fell victim to the scam, which saw them paying £5 for every text they received.