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(Reuters) – Fake security software was the No. 1 cybersecurity woe afflicting computer users in 2009, and Apple users lost some of their immunity to cybercrime as they stored more data online instead of on hard drives, according to the cybersecurity firm Symantec.

In a report released on Tuesday, Symantec noted that Brazil had risen to third place in the list of countries with "malicious activity," defined as spam, online scam attempts and other types of cybercrime. The United States remained in first place at 19 percent, with China second at 8 percent, and Brazil third at 6 percent.

Conficker — a malicious software program all over the news last April — and sophisticated attacks on websites of Google Inc and other large companies in December and reported in January were the most publicized cyber events of the year.

But the single most prevalent form of cybercrime was fake security software, which computer users normally see as a flashing notice that their computer is infected with a virus, said Vincent Weafer, a Symantec vice president.

The notice often provides a link to software that can be downloaded after payment, but the user does not get security software but rather, a virus or worse, Weafer said.

"Virtually everything we see today is fake AV (anti-virus)," he told Reuters. "It’s such a money-making racket."

The scam is popular is because victims willingly hand over their credit card numbers, thinking that they are purchasing legitimate software, and those credit cards can then be used at will.

Weafer also warned that Apple users, as they move their computer activities like storing photographs in remote servers managed by online companies, will have to take the same precautions that savvy PC owners have used for years to avoid identity theft. These precautions include keeping credit card and other key numbers secret and being suspicious of offers that seem too good to be true.

"It’s the notion of ‘I’m on a Mac.’ Yes, you’re on a Mac but you’re in the cloud," said Weafer. "They’ve got to be as careful as anybody else."

(Reporting by Diane Bartz; Editing by Richard Chang)