Twice as many viruses as last year...
SirCam has topped the list as the world's most common virus in 2001 - beating off stiff competition from BadTrans, Code Red and Nimda.
Anti-virus vendors are already dubbing 2001 the year of the virus due to the sheer number of hugely damaging viruses released.
Corporate devastation was wreaked by the likes of Magistr, Funlove, Goner and Hybris, but it was SirCam that left the biggest mark. The worm caught on very slowly, but consistently remained in the top three viruses since it first came to prominence in July.
MessageLabs has caught 537,523 instances of the virus so far - more than double the number of the next highest, BadTrans.
Sal Viveros, director of marketing for McAfee ASAP, said the secret of SirCam's success was the fact it kept a low profile. "It didn't cause a huge mailstorm when it came out and it didn't have an easily recognisable subject line, so it kept on spreading slowly but surely, as many people didn't realise they had been infected."
SirCam causes problems because it mails out randomly selected files from a victim's hard drive as it propagates, potentially revealing sensitive information.
Alex Shipp, anti-virus technologist for MessageLabs, said: "The most important thing we've learnt from this year is that the virus threat is just going to keep growing, new viruses keep coming along at an ever-increasing rate, and the old messages don't die."
MessageLabs detected 10 times as many viruses in 2001 as it did in 2000. It now catches one virus in every 370 emails - compared to one in every 700 in 2000.
The busiest months of the year for viruses were November and December, showing the problem is just getting worse.
2001 was also the year where viruses that didn't rely on email started to gain importance. Code Red notably spread via a vulnerability in Microsoft's IIS web server software.
In November, Nimda added a new level of complexity by combining many different threats to spread via web servers, email and unprotected network shares.