Extortion has moved up on the list, accounting for 20 percent of attack motivations this year, up from 15 percent last year.
Even more attacks -- 28 percent -- are motivated by the criminals using them for marketing, to demonstrate their capabilities to would-be customers.
"Organizations that offer DDOS for hire are giving free trials," Sockrider said. "They'll take someone down for five minutes just to prove that they can."
DDOS attacks are also used to manipulate financial markets, to hurt competing businesses, or in disputes between rival criminal gangs.
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