Sixty per cent of the 530 organisations questioned said they had been victims of unauthorised access to their computer systems over the past 12 months, with the majority identifying the internet as the most frequent source of attacks.
Although the cost of damage from computer misuse fell by 56% from a high of $455m (£275m) in 2001 to $200m, the losses are in line with those in the years before 2001.
Theft of proprietary data caused the greatest financial loss, averaging about $2.7m for each organisation, followed by denial of service attacks, which cost the organisations surveyed a total of $65m. Losses from financial fraud fell from nearly $116m last year to $10m.
Virus attacks and insider abuse of networks were the most frequently cited form of attack, followed by misuse of laptops, system penetrations and denial of service attacks.
Only 30% of the organisations questioned reported breaches to the police. Sixty per cent felt rivals would use knowledge of the attack to their advantage, and 53% said they were unaware they could report the attack.