More than 97% of businesses have suffered virus attacks, hacking, fraud and other computer crimes within the past 12 months, a survey of 105 large companies by the High-Tech Crime Unit revealed.
Nearly 70% have experienced virus attacks, 20% denial of service and hacking attacks, 18% spoofing of Web sites and e-mail addresses, and 13% misuse of the Internet by employees.
Despite this, more than 33% of business allocate less than 1% of their IT spend to tackling computer crime, and only 6% spend more than 6%, the survey found.
Some 8% of firms said the High-Tech Crime Unit was not relevant to their business, in what the unit described as "extraordinary complacency" over the potential risks of computer crime.
"Over 54% of senior decision makers see the threat as serious but over a fifth do not take any audits to verify that their security processes are working properly. It is very much a case of 'we have a firewall and that's it,'" said Mick Dears, deputy head of the High-Tech Crime Unit.
The survey found that most companies regard sabotage of their data networks as the most serious risk, closely followed by virus attacks, financial fraud and hacking and denial of service attacks.
Although 66% of the firms questioned said they would report computer crimes to the police, in practice only 37% have done so, and in many cases this is simply to support insurance claims.