"If you look at the motive its mostly just kids, students on both sides attacking government sites or politicised companies," said Schneier, speaking at the Infosecurity Europe Conference in London. "Adults don't do it."
But Schneier comments have been sharply rebuffed by the founder of the company that produced the report.
"He doesn't know what he's talking about," said Roberto Preatoni of defacement monitors Zone-H. "iSKORPiTX is a 45-year old man and he's one of the people at the very top of our list [of web defacers]."
According to Preatoni the attacks do not come simply from individuals, but also from organised groups.
"There are groups of six or seven people who work together. It is very organised," Preatoni said.
The report highlighted a massive increase in web server attacks and defacements, recording over 400,000 in 2004. Targets included the US government, Microsoft and NASA.
Earlier this month SC reported iSKORPiTX defaced the website of the Ted Stevens Anchorage International Airport in Alaska, replacing arrival and departure times with a picture of the Turkish flag.