Virus writers continued to cause headaches for computer users over the festive period, with nearly one thousand new viruses appearing in December.
While most were ineffectual, the Zafi-D worm proved particularly devastating, and was top of Sophos's list of prevalent viruses in December, says Brett Myroff, CEO of local Sophos distributor NetXactics.
"Only 24 hours after it was discovered, Zafi-D accounted for over 72% of all virus reports, and one in 10 emails was infected by the worm. Even though it was only discovered mid-month, Zafi-D caused major havoc during the festive season, accounting for more than a third of all virus reports in December."
The worm spread by purporting to send cheeky seasonal cheer - the body of the email contains a lewd graphic of two "smiley" faces to fool users into thinking the infected attachment contains a joke, says Myroff.
"Such tricks have duped large numbers of users into opening the attachment and launching the malicious code."
Sober-I was the second most prevalent virus on the list with 20.7% of all virus reports, while Netsky-P came in third with 15.5%.
In its list of top 10 hoaxes for December, Sophos rated the Hotmail hoax as the most prevalent for the sixth month in a row, accounting for 32.7% of all reports.
"The Christmas-themed Elf Bowling hoax re-entered the chart last month, just in time for the holiday season. The hoax warns computer users to be wary of emails containing a game called Elfbowl.exe, which it claims to be a dangerous virus," explains Myroff.
"Although there have been viruses disguised as games, this warning is totally fake. However, it is possible for the game to be infected by a virus in the future and be redistributed via email."