Washington - (UPI) -- U.S. investigators warn that an e-Valentine might contain a malicious virus, the Storm Worm, linking those who open the card to a botnet, not a secret admirer.

A botnet is a network of computers under control of one user, unknown to the rightful owners of the computers. They can be used for denial of service attacks, identity theft, sending spam e-mails and spreading more "malware" to link more computers into the botnet.

FBI officials said a number of holidays last year were used to spread the Storm Worm through messages with links to supposed e-cards.

Computer users are warned to avoid any Valentine's Day mesages sent by unknown admirers, leaving suspicious e-mail unopened and especially not clicking on links in the e-mail.
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