A report has suggested hacktivists and gamers are becoming big instigators of net attacks that knock sites offline by bombarding them with data.
The report, compiled by Arbor Networks, looks at 10 years of distributed denial of service (DDoS) attacks.
Arbor said the ease with which they could be staged had made them a favourite for groups with a grudge.
It also said insecure home routers were being enrolled into large groups of devices that mounted the attacks.
Darren Anstee, a senior analyst at Arbor said in the early days of DDoS, cybercrime gangs had used them to extort cash from websites run by betting and gambling firms that could not afford to be knocked offline.
He said that attacks were now being mounted by different groups and had grown considerably in size.
Mr Anstee said: "There's been a massive jump in the number of very large attacks going on out there.
"In 2014 we saw more volumetric attacks, with attackers trying to knock people offline by saturating their access to the internet."
Almost 40% of the organisations that were contacted for the report by Arbor said they were being hit by more than 21 attacks per month.
Mr Anstee believes that part of the reason for the shift to large attacks could be explained by a change in technologies being used to stage them.
He said that when cybercrime gangs had been behind the majority of the attacks, the data barrages had been hijacked by the thousands of compromised home computers they had had under their control.
Figures in the report suggest that companies are getting better at spotting the early stages of an attack, and recovering once they are hit.
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