DefCon Kids camp co-founder Chris Hoff, with Conner Gilliam (from left), Conner Fine and Ethan Lai, work on a machine that draws designs on ping-pong balls. The camp is held in Las Vegas. Steve Henn/NPR hide caption

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Hackers used loopholes in the security at Amazon and Apple to obtain personal information about a Wired writer, who says his entire digital life was "destroyed." Experts say to ward off hackers, pick good passwords and get rid of unused accounts. iStockphoto.com hide caption

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This 2010 image, provided by IntelCenter, shows Humam Khalil Abu-Mulal al-Balawi in a posthumous video message posted on extremist websites. The al-Qaida double agent killed seven CIA operatives, a Jordanian spy and himself when he set off a bomb strapped to his body at a base in Afghanistan in December 2009. AP/IntelCenter hide caption

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In January, the hacker group Anonymous staged a demonstration at a BART station in San Francisco after officials turned off cell phone service in its stations. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images