However, Dhanjani also demonstrated more positive uses of social-network mining. He demonstrated a tool that can filter posts on Twitter by geographic area and search for particular keywords, such as posts mentioning "fire" or "smoke" to provide an earlier warning for emergency responders.

Dhanjani suggested that social networks could also assist with criminal investigations. Today, investigators talk with friends and associates of known criminals to identify accomplices. The connections on social sites could help reveal which people are closest to a target, he said.

Previously, Dhanjani identified a likely credit-card criminal by watching his behavior across a number of social-networking sites. Dhanjani was able to connect the criminal's profile to a suspected true identity, partly through an analysis of his postings.

Other researchers agree that social-networking sites reveal far more than users often intend. "Legitimate software now does everything malware used to do that we freaked out about," says Hamiel of Hexagon Security.

Dhanjani noted that social networks have both positive and negative qualities. "I think social media is beautiful, and I use it, too," he said. As a security researcher, he tries to be careful about what he reveals when he uses Twitter, but he's discovered that it isn't possible to fully protect his privacy. "Social media is like a cocktail party," he said. "In order to get something out of it, you have to give something up."