Most people have learned to keep a lid on their Social Security number, but they're happy to toss around their phone number at will. As two security experts demonstrate to the Los Angeles Times, that's becoming dangerous in the age of smartphones. Through those seven digits, hackers can hijack your phone (and the personal universe it contains) to figure out the pattern of your comings and goings, even listen to your messages or read your texts. Download one bad app and you're especially compromised.
"We can do a lot of cool things that we really shouldn't be able to as civilians," says one of the so-called "white hat" hackers. "It's like running your own private intelligence company." Industry observers liken the current state of smartphone security to the early days of the PC—before people learned to put up firewalls and virus protection.
(More smartphone hacking stories.)