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Cyber Stalking: Cal app creates “heat map” of your movements

September 9, 2013
Image of an iPhone showing a map

At precisely 3:26 p.m. on July 17, Britney Spears was recording music at the corner of West Oak Street and South Glenwood Place in Burbank, California. On August 23 at 4:21 p.m., Katy Perry was in rural northeast Colorado, at the intersection of Highways 46 and 55. And on August 5 at 3:56 p.m., Oprah was cruising down the Kennedy Expressway outside of Chicago’s Bucktown neighborhood.

We know these things from their Twitter and Instagram feeds. But they didn’t tweet their location or check in on FourSquare—we used the new web app Ready or Not?, which can create a heat map of where someone’s been for the last 30 days based on the metadata encoded in their Twittter and Instagram posts. And when it comes to this kind of vulnerability, celebrities really are just like you.

When you post something on Twitter or Instagram through your phone, all you see is your tweet or picture, but there’s a wealth of information contained in the automatically generated metadata—including your location, the time you posted and more. It doesn’t take a PhD in computer science to access this metadata. All it takes is some basic programming skills and a few lines of code.

“Undergraduates and high schoolers are the generation that is most affected by social media and yet have the least notion of privacy.”

That’s the warning from UC Berkeley computer science lecturer Gerald Friedland, principle investigator on the app, which shows how your social media postings could be used to track you, and what you can do to protect your privacy. 

The Ready or Not? app is the work of UC Berkeley’s International Computer Science Institute’s Teaching Privacy Team, a group of computer scientists, educators and social scientists who aim to help the public make smarter decisions when sharing personal information online. Funded by a National Science Foundation grant, the team is aiming to expand its website, create more apps, and encourage parents and teachers to share and adapt their material.

“The response has been very interesting. Most people didn’t know about this and most are like, ‘Oh damn, how can I turn this off?’ ” Friedland says, adding that most of his computer science colleagues were also unaware of the automatic geotags. “If a PhD in computer science doesn’t know this kind of thing what about a) a person on the street, and b) high schoolers, who are still exploring everything?”

Friedland became interested in the implications of geotagging in 2010, after co-authoring a paper about cyber-casing that concluded that online data enables crimes that previously wouldn’t be possible. As he discussed his findings with students, he found that most had no idea about geotags, and as he and his team continued their work, they decided to make their research more accessible by creating an educational component.

“Undergraduates and high schoolers are the generation that is most affected by social media and yet have the least notion of privacy,” Freidland says. “If you ask a 16, 17 year old they’ll say, ‘Oh, I don’t Facebook that much, I only go on three times a day.’ If you go on three times a day for many years, you can extract everything, their habits, location—they’re completely trackable and this (information) is public.”

The site also offers advice about maintaining privacy online. A list of ten “Principles for Social Media Privacy” warns “There Is No Anonymity on the Internet” and that “Your Information Footprint Is Larger Than You Think.” Real life examples of online data-sharing gone awry are also mentioned: two UK friends barred from the United States after making a joke on Twitter about “destroying” America, a Cleveland-area Burger King employee who posted an anonymous photo of himself standing on containers of the store’s lettuce was identified within 15 minutes because of geotags, and users of Fitbit discovered that personal data about themselves—including the duration of their sexual activities—was easily accessible to anyone doing a Google search.

Friedland also points to a 2011 survey by a UK home security company Friedland (no relation) in which 78 percent of the ex-burglars interviewed said they believe social media is helpful to criminals.

If you’re concerned about your electronic trail, Friedland recommends turning off location services on your smartphone for apps that don’t need your location—on for Maps, off for Candy Crush and Angry Birds. When posting pictures online, convert them to PNG: your location metadata will be harder to access than in JPG or TIFF formats.

Friedland says the goal of Ready Or Not? isn’t to inspire fear or advocate for a social media-free existence. “I’m not saying, ‘Oh we should all be more private,’ ” he insists. “I’m saying look, if you post this, then this and this is going to be posted with it. I want people to say, ‘I know what’s happening when I post, and this is my conscious decision, instead of not knowing what’s going on.

—Shelby Pope 

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