As features that use your location creep into social networks, some people are voicing concerns about whether the capability is a greater hazard to privacy and safety than a boon to meeting up with friends. Mobile apps like Foursquare and Gowalla, social networks like Twitter, and even the photos you snap on your mobile phone can give up information you never even knew was public.
While the privacy concerns around Foursquare have been demonstrated by a site called Please Rob Me, another site is now showing the hazards of location information in Twitter. ICanStalkU.com reveals the hidden location information in Twitter's public tweet-stream, uncovering the location data in posts by converting it to street addresses.
As the New York Times reports, new smartphones like the iPhone 4 can also give up things like your home address when you post photos, because they automatically append "geotags" to the image file. The standard JPEG file format allows a variety of additional information to be attached to it, such as the camera type and exposure information, as well as information about where the photo was taken. And that caught Mythbusters co-host Adam Savage by surprise.
When Adam Savage, host of the popular science program "MythBusters," posted a picture on Twitter of his automobile parked in front of his house, he let his fans know much more than that he drove a Toyota Land Cruiser. Embedded in the image was a geotag, a bit of data providing the longitude and latitude of where the photo was taken. Hence, he revealed exactly where he lived. And since the accompanying text was "Now it's off to work," potential thieves knew he would not be at home.
Whoops. Savage has since gone into his iPhone's settings and disabled the automatic geotagging for photos—something that ICanStalkU provides instructions for.
You can turn choose not to use location information associated with your Twitter account if you're using it on your mobile device (or even on your home PC, since your Internet address can give away at least the neighborhood you're in). On the "settings" page for your Twitter account, make sure that the box next to "Add a location to your tweets" is unchecked.
Facebook is also planning to provide location-based services in the near future—mostly to help you find local services and present the right kind of ads to you. When that security setting becomes available, I'll be sure to post how to turn it off here.