MADISON, Wis. -- An e-mail offering a look at Wednesday's lunar eclipse instead delivered a virus to the state's computer system.

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The e-mail went to about 4,000 state employees, and it sent some officials with the Division of Enterprise Technology scrambling to protect state computers.

The e-mail offered "shocking video" of the lunar eclipse, and clicking on the link activated a virus that can download sensitive information.

Officials said that only 12 employees actually clicked on the link and that the virus was contained before any information was compromised.

Security officials said there is an easy way to avoid being an e-mail victim.

"The most important thing (is to) never click on unsolicited links in e-mail. You never know what's going to be downloaded," said Mike Lettman, director of Information Security at the Division of Enterprise Technology. "Their tactics are to send out as many e-mails as possible. If they can get 1 percent of the people to click on this link, it's a bonus and a win-win for them and a way for them to harvest information."

Lettman said that typically, malicious e-mails or "malware" try to get Social Security numbers or account user names and passwords.

But the state stores its passwords differently, so officials said they weren't at risk.

Lettman said the state is a huge target of online thieves. He said they get 8 to 10 million spam or malicious e-mails each day. To defend against them, the state runs 19,000 scans every hour.