The numbers of computers infected by viruses is stabilising but the malicious programs pose as big a problem as ever.
Companies are taking viruses more seriously
A survey reveals that the number of virus infections per thousand computers stayed almost static in 2002, but the disruption they caused soaked up more time and money than ever.
The report said this was because the latest viruses are more likely to delete data, clog networks and choke mail servers.
The damage they can do has led increasing numbers of companies to install software and hardware to help them beat off viruses and other malicious programs.
Computer viruses have become a fact of life for anyone using e-mail and the internet.
Figures published as part of the annual virus prevalence survey by the respected ICSA Labs shows that, last year, 105 machines out of every 1,000 had an encounter with a virus every month.
In 2001 the figure was 103 encounters per 1,000 machines per month, a huge increase on five years ago when the figure was 32 encounters per 1,000 machines per month.
Ordinarily, said Larry Bridwell, ICSA spokesman and co-author of the report, a slow down in the rate of virus infections would be a good thing.
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However, he said, any company caught out now is likely to suffer much more than anyone hit by a virus a few years ago.
"Viruses have gone from being a nuisance to now where there is loss of data, loss of productivity and people cannot get to their machines," he said.
Three-quarters of those questioned for the survey said that machines and people had been tied up by dealing with a virus outbreak and 62% said files had been corrupted by malicious programs.
Mr Bridwell said that the cost of recovering from a virus attack and the time it takes to clean up and get back to normal working are all rising.
The cost of cleaning up after an outbreak rose to $81,000 in 2002 from $69,000 in 2001.
On average companies were taking 23 days to recover from outbreaks. In 2001 the figure was 20 days.
Virus outbreaks have regularly caused havoc
Part of this lengthening recovery time is due to the fact that computer networks have become more ubiquitous and complicated. As a result cleaning up after a virus and ensuring it is purged from all systems takes more time.
The good news revealed by the survey is that more companies than ever are using anti-virus software and filtering e-mail messages and blocking certain file types from travelling through mail gateways.
Mr Bridwell said the reason for this was the fact that viruses are getting more malevolent.
"Viruses really were not that dangerous," he said. "But now if you have one of these incidents the cost is so much higher to recover that you need to mitigate the risk more than ever before."
Details of the 8th Annual ICSA Computer Virus Prevalence Survey were released at the Information Security Show held at Olympia in London from 29 April to 1 May 2003.