Cyber-criminals are increasingly harnessing the popularity of group discount deals.
According to a third quarter study conducted by Kaspersky Lab, there has been a rise in the number of malicious emails disguised as official advertisements and notifications from coupon services. This type of email, which Kaspersky calls "an ideal disguise for malicious users," now accounts for 3.9 per cent of all email traffic. The figure stood at three per cent during the second quarter.
"Kaspersky Lab experts expected to see the appearance of this type of spam since coupons are very popular among Internet users, and they trust coupon services," wrote Kaspersky.
Worryingly, this form of attack is increasing in quality as well as quantity. The study notes that the layout of the emails has been improved upon, making them more intelligent and subtle. The first such email – initially detected by Kaspersky Lab in July – contained an attached executable ZIP file called Gift coupon.exe, which in turn held a Trojan. All links in the email itself safely led to Groupon's website.
In contrast, the newest emails have dropped all attachments, and instead harbour malicious links.
Kaspersky has offered two pieces of advice to concerned Internet users: "First of all, coupon services will never include attachments in their emails – especially in the form of a ZIP file or an executable.
"Second, users can and should always make sure that an email that is apparently from a well-known service should at the very least have the correct sender name in the FROM field, and that all of the links lead to the site that they claim to (check this by hovering the mouse over the link)."
The study indicates that malicious imitations of emails sent by Groupon appear to be the most widespread, though fakes claiming to have been sent from banks, social networks, online stores and other services were also numerous.
Elsewhere, the overall detection of email spam in the UK fell by 1.7 per cent, to 5.57 per cent – the fifth highest in the world.
Image Credit: Kaspersky Lab