According to a survey of 56 corporate and governmental organisations in the the US conducted by the Ponemon Institute, the average amount they paid for all the costs associated with cyberattacks was £6 million ($8.9 million) during the past year. That's up 6 percent from the previous year's study.

And for the first time, Ponemon expanded the survey to other countries, including the United Kingdom, Germany, Australia and Japan. Costs ascribed to cyberattacks in those locales was significantly lower: £3.7 million ($5.9 million) in Germany and $5.1 million in Japan, for example.

In the UK and Australia, where cybercrime costs per year were $3.2 million and $3.3 million respectively, denial-of-service attacks were more commonplace. German companies were the least likely to experience malicious code and denial-of-service, while Japanese companies least likely to experience malicious insiders and Web-based attacks.

The study, sponsored by HP Enterprise Security, offers some explanation for why the US cybercrime figure is far higher. "We found that US companies were much more likely to experience the most expensive types of cyber attacks, which are malicious insiders, malicious code and web-based incidents," the report says.

Institute founder Larry Ponemon acknowledges that with only 56 organisations participating in the survey, the sample is insufficient to reach a firm conclusion as to why the cost of cybercrime in the US does appear higher than elsewhere.

The study cited five "external" cost factors associated with cybercrime: business disruption, information loss or theft, revenue loss, equipment damages and "other." The "internal cost" factors were detection, investigation and escalation, containment, recovery and subsequent efforts to ward off future attacks.

US companies cited information theft as accounting for 44 percent of total external costs.

Cybercrime costs among the 56 companies participating in the survey ranged from $1.4 million to $46 million. Most of the cybercrime costs were related to mitigation of attacks caused by denial-of-service, malicious insider and Web-based attacks.