Hackers have combined spam and malware together in a single email threat.
Email security services firm MessageLabs has intercepted emails that are both spam and links to download viruses. Cyber-criminals have long used email viruses to create botnets to send spam, but this is the first time MessageLabs has seen virus links hidden within spam.
Since 14 April, MessageLabs has stopped thousands of spam stock pump-and-dump emails which also contained links to websites hosting malware. Purporting to be a screen saver, the malware then drops the Zhelatin MeSpam engine onto compromised PCs.
Mark Sunner, chief security analyst at MessageLabs, commented: "Why use two emails when just one will do? Now we are seeing the bad guys layer on the threats – as if it's not enough to just scam someone and fill their inbox with junk email, why not also infect and take control of their computer at the same time."
"HTTP has replaced SMTP [email] as the path of least resistance," he added.
Large scale virus outbreaks have almost become a thing of the past - hackers have increasingly sought to trick users into visiting websites containing malicious code rather than open infectious email attachments. This means that even as spam volumes increase, the volume of malware contaminated email is dropping.
MessageLabs reckons 83.6 per cent of email traffic circulating the internet in April was spam. Meanwhile, the global ratio of viruses in email traffic - from new and previously unknown bad sources destined for valid recipients - was one in 145.5 (0.69 percent), a decrease of 0.003 percent since March.
Email-based attacks are becoming more targeted. Last month MessageLabs intercepted 716 emails in 249 separate targeted attacks aimed at 216 different organisations. Of these, almost 200 were one-on-one targeted attacks where the tailored attack comprised a single email designed to infiltrate an organisation. Infected PowerPoint files are becoming almost as common as infected Word files. By comparison, only one or two such email attacks per day were recorded in the same period last year. ®