According to antivirus company F-Secure, reports are rolling in of Atak.H, which poses as a Christmas or New Year greeting.
"There are different levels of risk with these e-mail Christmas cards," Mikko Hypponen, director of antivirus research for F-Secure, said Thursday. "It's very similar to past ones we've seen. There's little risk in sending Christmas cards, but there is in opening them. We recommend people send old-school Christmas cards because there's no security risk in that."
The virus, which is similar to the Zafi worm currently causing havoc on the Internet, spreads to all the addresses in a victim's address book. But unlike the multilingual Zafi, Atak only sends itself in English.
According to F-Secure, the virus does not contain a Trojan horse--a tool that virus writers often use to take remote control of computers. Hypponen said this is strange.
The worm, which was discovered Wednesday, contains the subject line "Merry X-Mas!" or "Happy New Year!" The body of the text reads: "Happy New year and wish you good luck on next year."
Dan Ilett of ZDNet UK reported from London.