By Mark Ward BBC News Online technology correspondent

Shakira: Popstar and pernicious program

If 2001 was the year of the big hitting computer virus, 2002 was the year of the slow burner.

In 2001 viruses such as Code Red and Nimda prompted warnings of internet meltdown and made many local parts of the net unusable for people connected via those links.

The last 12 months may not have had as many headline grabbing viruses, but many of the novel malicious programs debuting in 2002 had significant staying power and rattled around the web for months.

Experts say the year has also shown some worrying trends and emphasised the importance of keeping anti-virus software up to date.

Worm warning

The biggest virus of 2002 was the Windows Klez worm which first appeared in March.

According to figures from anti-virus firm Sophos, the virus accounted for almost a quarter of all the virus reports the company received in 2002.

We are going to see more convictions of virus writers Graham Cluley, Sophos

Virus catching firm MessageLabs said it captured more than 10 million viruses throughout 2002, and almost five million of those were copies of the Klez worm.

The self-spreading worm travels by finding e-mail addresses it finds in Windows Outlook, instant messaging programs or in files on the infected machine.

Klez has been so prolific because it contains its own e-mail engine and the subject line of any infected e-mail is regularly and randomly changed making it hard to warn people about it.

It can also be hard to warn people that they are infected because the virus fakes the address it came from.

Threat analysis

Graham Cluley, senior technology consultant at anti-virus firm Sophos, said Klez was a good example of the type of program popular with virus writers.

Most active viruses in 2002

W32/Klez.H-mm W32/Yaha.E-mm W32/BugBear.A-mm W95/Klez.E-mm W32/SirCam.A-mm W32/Magistr.A-mm W32/BadTrans.B-mm W32/BadTrans.B-mm W32/Hybris.gen-mm EML/Greeting-Card

Previously virus writers had favoured so-called script virus such as the Love Bug.

By contrast is a Windows 32 executable file. Almost 90% of virus reports in 2002 were about such programs.

Ironically, said Mr Cluley, such viruses are easy to stop with a properly configured e-mail gateway.

This year saw virus writers continuing to use the names of popular woman celebrities to try to make people open an e-mail and unleash its malicious payload.

Colombian popstar Shakira, singer Britney Spears and actress Jennifer Lopez have all been used to name viruses.

Spam attack

The last year also showed a significant rise in the numbers of viruses in circulation as well as the appearance of several hundred new viruses. There are now more than 78,000 known viruses in existence.

When Message Labs started scanning e-mail for viruses it was catching one virus every 60 minutes. In 2001 this leapt to one every 30 seconds. In 2002 the rate hit one every three seconds.

One worrying trend was the emergence of marketing companies that use virus techniques to spread their message.

2002 lacked a headline hitting virus

One of the first to use this technique is Panamanian company Permissioned Media which buries the agreement to let it plunder e-mail address books in the small print of its license agreement.

But, said Mr Cluley, despite these increases there were some encouraging signs for those fighting the spread of these malicious programs.

David L Smith, the writer of the Melissa virus, was finally sentenced and 2002 saw the capture trial and charging of several other virus writers.

This is a trend that Mr Cluley expected to see continue in 2003.

"I'm positive we are going to see more convictions of virus writers," he said.

"We need to get away from the idea that these guys are geniuses," he said, "that is really the wrong message to send to these kids."

"Viruses have real victims, its not just faceless corporations," he said.