Stay one step ahead of the fraudsters with our series of articles giving you the lowdown on the scams they use to trick people out of their hard-earned cash - and how to avoid being taken in by them.
This week, we explain why supermarket money off vouchers circulated on social media are often not what they seem.
How does it work?
Internet fraudsters are targeting Facebook users with dodgy vouchers promising them money off their food shopping, but actually designed to infect their computers with malicious viruses.
The latest scam purports to come from the supermarket chain Aldi: "Get a Free £85 Aldi coupon to celebrate 55th Anniversary!" However, similar messages have also been sent out in the name of Lidl, Waitrose and Spar.
In each case, anyone who clicks on the link to claim the offer is directed to survey page designed to collect their personal information, and asked to share the offer on their social media profiles.
None have received money off their shopping, and some have been hit with annoying malware and viruses that are damaging to computers and laptops.
How can I avoid being caught out?
Supermarkets rarely attempt to boost their sales in such a general way online. Aldi said: "We don't offer electronic coupons or electronic gift cards, and they won't be accepted at our stores."
If you are tempted by an offer, you should therefore check it out before clicking on any potentially dangerous links - and avoid giving out any of your personal details until you are sure it is genuine.
Tony Neate at security adviser Get Safe Online said: "If you're uncertain if a post of this type is legitimate, never input your personal details to unlock an offer.
"If in doubt, you can also do your own detective work by searching for the offer on the shop's site first, or take a look at the advice on the Get Safe Online website."
I've been defrauded. What should I do?
First things first: change any passwords and login details that may have been made available to the fraudsters.
If you clicked on a potentially dodgy link, you should also conduct a malware check using an online virus scanner such as the Microsoft Safety Scanner. Then report the problem to Action Fraud (0300 123 2040).