2011 was the year of the hacktivist, according to a study from Verizon, which shows that 100 million users saw their data compromised by Anonymous-related activities last year.

The wireless carrier’s annual Data Breach Investigations Report (embedded im toto below) includes data from security-breach investigations conducted around the globe by a range of law enforcement officials and other entities such as the Dutch High Tech Crime Unit and the U.S. Secret Service.

Of 855 data-breach incidents recorded last year, only around 25 were attributed to Anonymous hacktivists. However, Anonymous’ activities accounted for a full 25 percent of the data breaches at large organizations, which are generally the kind of entities targeted by the collective, anyhow.

And of the 174 million individual records compromised in 2011’s hacks, around 100 million came via Anonymous. Altogether, the report says, 58 percent of all data theft last year was the result of hacktivist efforts.

“This re-imagined and re-invigorated specter of hacktivism rose to haunt organizations around the world,” the report reads.

“Many, troubled by the shadowy nature of its origins and proclivity to embarrass victims, found this trend more frightening than other threats, whether real or imagined. Doubly concerning for many organizations and executives was that target selection by these groups didn’t follow the logical lines of who has money and/or valuable information. Enemies are even scarier when you can’t predict their behavior.”

The report continued that, while Anonymous definitely made a big splash in the security world last year, mainstream cyber-crime continued to focus on weak targets and low-cost, high-volume attacks.

“The more data we can share with the industry, the better we can understand and prepare for the threats we collectively face,” writes Verizon infosec guru Dave Hylender on the carrier’s security blog. “We believe that with each passing year, the data grows and evolves helping to paint a more complete picture of the current state of cybercrime.”