A new seasonal worm is making the online rounds with a holiday message, but its present is a viral payload. The cyber security center at the National Intelligence Service has issued a warning against the mass-mailing worm disguised as holiday greetings.

The malware, called Zafi.d., features the subject line "Merry Christmas" or "Happy Holidays", and appears to be an electronic greeting card from someone the recipient knows.

The center is advising personal computer users to remain alert against possible damage from the worm or "pishing schemes" during the year-end holiday season.

Meanwhile, a local anti-virus firm, AhnLab, says the number of virulent computer viruses that have hit the nation this year as of December 10th amounted to some four-thousand-400, which is one thousand more than the total number of cases that have appeared over the last 16 years combined.

A company official advised computer users to delete suspicious mails without opening them.