(NEW YORK) -- The websites of Sega, Sony, Citibank, and the U.S. Senate have all been hit by hackers.
In Sega's case, the firm said over the weekend that the attackers got access to account information for 1.3 million users. And that wasn't even unusual.
Somewhere out there are loosely-organized shadow groups -- there's one that calls itself Anonymous, another that registered a website in the Bahamas under the name Lulz Security -- trying to take credit for some of the more public attacks.
Security consultants said you're probably safe if you take precautions -- such as deleting emails from strangers and changing your passwords regularly. Most firms that handle sensitive data, such as credit card numbers, try to stay a step ahead of the intruders. But it's full-time work.
Hacking -- once seen as the pastime of geeky teenagers who didn't have better things to do with their technological skills -- has apparently ballooned in just the last few months. Google's Gmail service was attacked from somewhere in China, and there have been debates over whether cyber attacks from other countries qualify as acts of war.
"It feels to me like there are definitely more hacks taking place," said Graham Cluley, who analyzes online trends for the computer-security firm Sophos. In an email to ABC News, he broke the attackers into three types:
-- "Hacktivists: They may be doing it for laughs, or believe they are making a political point, but they don't have a financial motive," Cluley said.
-- Genuine criminals: Cluley called them "your regular identity thieves -- interested in stealing identities, credit card detail, because of the money that can be made out of them."
-- Infiltrators: "These are the hackers who appear to be hacking organizations and government bodies with the intention of stealing sensitive information with -- perhaps -- military or economic motivation," said Cluley.
He cited attacks on U.S. military contractors, such as an internal network at the aerospace giant Lockheed Martin as a recent example.
Cluley said one likely increase was in the number of organizations admitting they'd been hacked. The number of attacks is tremendous, he said, though most are unsuccessful or, in many cases, merely annoying.
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