18- to 24-year-olds most at risk for ID theft, survey finds

"You are trading information about yourself as a form of cultural currency," Madden said. "By posting a photo or an update about what you did at a bar last night, you are sharing with friends to initiate an exchange and continue a friendship."

Problems arise, she said, when the information is misused.

"It's an interesting balance they have to strike in deciding how much to share in order to initiate or maintain a relationship but not overshare with their network," she said.

Madden pointed to studies that show most people can be identified with three pieces of information: their sex, Zip code and date of birth. And seemingly anonymous profiles that catalogue preferences, such as movie lists on Netflix, can also be used to identify users.

Adam Morrison, 19, a freshman at Arizona State University, realized that his identity had been stolen a few summers ago when he applied for a job and figured out that someone had been using his Social Security number for his own employment purposes. Morrison's bank account was not affected, but he remains miffed about how long the person had been using the Social Security number and how it was stolen.

"No idea how he got it," Morrison said.

Staff writers Matt Zapotosky and Jenna Johnson contributed to this report.