Rather than the expected joke, a file attached to the email unleashes a new variant of the Storm Trojan, according to security firm McAfee.

Also known as Nuwar, the Storm Trojan has been appearing in email attacks for more than a year and typically attempts to grab the attention of the recipient with subject lines relating to topical events or significant dates such as New Year or Valentine's Day.

McAfee warned that the email contains a message asking you to click on a link if the download does not begin within five seconds. There is also a clickable image.

Whether you click on the link, the image, or simply wait the email will attempt to download the malware to your PC.

"If you wait those five seconds, it'll try to download file funny.exe to your computer. If you click on the image, it's kickme.exe. And if you click on 'click here' it's foolsday.exe. All of them are nothing but a new Nuwar variant," wrote Dmitry Gryaznov on the McAfee Avert Labs blog.

www.avertlabs.com

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