WASHINGTON (4/27/15)--Distributed denial of service (DDoS) attacks can, at best, be an annoyance for a business or organization trying to run a website. At worst, they can expose weaknesses that cybercriminals can exploit.

DDoS attacks began as a method for cyber thugs to halt website activity or inflict damage by flinging heavy volumes of traffic at an organization's website, but a new report from VeriSign shows that these attacks are becoming even more difficult to handle, and subsequently more costly.

In the fourth quarter last year, the size of the attacks--measured by gigabits per second--rose by 14% on an annual basis.

Further, VeriSign found that the number of attacks jumped by 17%, with 15% of the attacks targeted at financial institutions.

"The increasing availability of DDoS-for-hire services--also known as 'booters'--presents a huge risk for security professionals, as they enable virtually anyone to hire skilled cybercriminals to launch a targeted DDoS attack for as little as $2 per hour," VeriSign said in the report.

Rik Turner, senior analyst at the research and consulting firm Ovum, told American Banker recently that DDoS attacks also have become more sophisticated.

"We're seeing lots of small attacks with intervals that allow the attackers to determine how efficiently the victims' mitigation infrastructure is, and how quickly it is kicking in," Turner said.

These attacks also can cripple network availability and productivity, and cost organizations greatly in both online revenue and in reputation and customer trust, according to VeriSign's report.

Given what's at stake, VeriSign says that awareness of the capabilities of these criminals is one key to combating the DDoS threat.