Cheshire Cat Photo Blog(...said the Cat: 'we're all mad here....')

No, not THEIRS – YOURS… the photographer’s!

At the Next HOPE hacker conference in New York on Friday, security researcher Ben Jackson of Mayhemic Labs demonstrated how he scanned over 2.5 million photo links that were posted to Twitter and extracted the longitude and latitude of of the location where 65,000 photos were taken. The coordinates are embedded in the EXIF metadata of photos taken with many devices, typically without the knowledge of the person taking the photo.

While most professional photographers and serious amateurs know about EXIF metadata and use it to store information about copyright and contact information for the photographer, a lot of amateur photographers may not realize that the last couple of generations of cell phones may geotag photos as the default. (Hmmmm, why is THIS the default? ) The location coordinates are embedded into the EXIF metadata of images taken by such cameras. (Note, this is different from the “geotag-this-message” feature that Twitter and some similar services offer.)

So, as a result, even though you may be doing what you think is an adequate job to conceal your identity and protect your privacy on Twitter and elsewhere, you may be posting the coordinate data to identify the location of your home, for example!

Mayhemic Labs created the Web site, ICanStalkU.com, to raise awareness about inadvertent information sharing.

“A Perl script samples a subset of image links from Twitter, including Twitpic, Yfrog, and Sexypeek, and examines the EXIF metadata to see if latitude and longitude coordinates are embedded.”

“If they are, the coordinates are converted to a street address if possible (or a city name if not) and posted on ICanStalkU.com. About 3 percent of images posted to Twitter are geotagged through EXIF, Jackson says.”

“It’s completely random,” he says. “We freak people out.”

iPhone and other phones allow users to disable geotagging of photos (Location Services settings menu on the iPhone), but not all folks have enabled that privacy setting.

Read the CNET article to see just what you can learn about Twitter tweeters, in real time.

Once again, why is automatic geotagging the default? If you’ve been a regular reader, you know why.

(Note added October 16, 2010: See this later CNN article about geotagging in EXIF data of photographs.)

-Bill at

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