A virus posing as a Valentines message has been spammed to email recipients in a global campaign, it was reported today.

The Dref-AB worm attaches itself to emails with subject lines, including “Be My Valentine” and “Happy Valentine's Day”, in an attempt to entice users into clicking on a malicious attachment, which activates the virus.

Once activated, the worm is designed to download further malicious code onto the user’s computer, which allows the hacker to take control of the machine and form a botnet, according to security experts.

The worm is connected to the email in files, including flash postcard.exe and greeting card.exe, and has accounted for more than three-quarters of all malware detected by Sophos throughout the night.

“This new attack is spreading hard and fast across the net. Cynical hackers are using the theme of Valentine’s Day to conquer innocent people’s computers and use them for their own money-making purposes,” said Graham Cluley, senior technology consultant at Sophos.

“No-one shold be blinded by the excitement of today into opening unsolicited attachments or clicking on links to unknown websites, as you could be falling deep into a hacker’s trap.”