Cybercrime is not only becoming more frequent -- it's becoming more expensive for the victims, according to a study published today.

In its Second Annual Cost of Cybercrime study, the Ponemon Institute surveyed 50 large companies to determine the losses and expenditures caused by cybercrime. The study, sponsored by security information and event management company HP ArcSight, indicates that the cost of cybercrime has risen 56 percent since last year's report.

"We found that the median annualized cost of cybercrime for 50 organizations in our study is $5.9 million per year, with a range of $1.5 million to $36.5 million each year per company," the study says.

Some of the other findings:

Cybercrime cost varies by organizational size. The study results reveal a positive relationship between organizational size (as measured by enterprise seats) and annualized cost. However, smaller-sized organizations incur a significantly higher per capita cost than larger-sized organizations ($1,088 vs. $284).

The companies participating in the study experienced 72 successful attacks per week – or more than 1.4 successful attacks per organization. This figure has increased 44 percent over last year, Ponemon says.

The most costly cybercrimes are those caused by malicious code, denial of service, stolen or hijacked devices, and malicious insiders, according to the study. These account for more than 90 percent of all cybercrime costs per organization on an annual basis.

Cyber attacks can get costly if not resolved quickly, the study says. Results show a positive relationship between the time to contain an attack and organizational cost. The average time to resolve a cyberattack is 18 days, with an average cost of $415,748 over this 18 day period. This represents a 67 percent increase from last year’s estimated average cost of $247,744, which was compiled for a 14 day period.

Results show that malicious insider attacks can take more than 45 days on average to contain, Ponemon says. Information theft continues to represent the highest external cost, followed by the costs associated with business disruption. Information theft accounts for 40 percent of total external costs (down 2 percent from 2010). Costs associated with disruption to business or lost productivity account for 28 percent of external costs (up 6 percent from 2010).

Recovery and detection are the most costly internal activities associated with cybercrime, according to the study. Recovery and detection account for 45 percent of the total internal activity cost, most of it spent on cash outlays and labor. Having an SIEM system can help, according to Ponemon. "We found a percentage cost difference between SIEM and non-SIEM companies of 24 percent," the study says. "Findings suggest companies using SIEM were better able to quickly detect and contain cyber crimes than those companies not using SIEM