Dark Reading

Researchers from the University of Cambridge today announced the results of a new study demonstrating that many social networking sites maintain copies of user photos after users delete them. This could be an unpleasant surprise to users who believe they have deleted an embarrassing photo, only to find out it is still available on the web.

The study examined 16 popular web sites which host user-uploaded photos, including social networking sites, blogging sites, and dedicated-photo-sharing sites. 7 of the 16 sites surveyed were still maintaining copies of users' photos after 30 days.

To perform their experiment, the researchers uploaded photos to each of the 16 sites, then deleted them, but kept note of direct URLs to the photos from the sites' content delivery networks.

These links continued to work even though a typical user would think the photos were permanently deleted. There is no simple interface to tell when a photo has ultimately been purged from a site due to the technical details of how photos are stored.

It is common practice for Web 2.0 sites to store user photos on servers run by a different company. The popular sites Facebook, MySpace, and hi5, for example, all serve photos from the content delivery network run by Akamai Technologies, Inc.

As this study found, by keeping note of the URL where the photo is actually stored in a content delivery network, it is possible to access the photo even after a user believes they have deleted it. Any mention of this behaviour is usually buried in obscure legal language in a site's terms and conditions.

Social networking sites fared especially poorly in the study, with 4 of 8 failing to remove deleted photos, including industry leaders Facebook, MySpace, hi5, and Bebo. Blogging sites also fared poorly, with LiveJournal, Xanga, and SkyRock all failing to remove photos.

Faring well in the study were the dedicated photo-sharing sites Flickr, Photobucket, and Fotki, which all removed photos within 1 hour. Three Google-operated websites, Blogger, Picasa, and Orkut, all removed photos within 48 hours. Microsoft's Windows Live Spaces received special commendation for removing photos instantly.

The study was conducted by PhD students Joseph Bonneau, Jonathan Anderson, Andrew Lewis, and S"ren Preibusch, and lecturer Frank Stajano, who have been researching social networking privacy and have reported numerous other flaws.

Said Joseph Bonneau, "This demonstrates how social networking sites often take a lazy approach to user privacy, doing what's simpler rather than what is correct. It's imperative to view privacy as a design constraint, not a legal add-on."

Said Jonathan Anderson, "This experiment is a litmus test of which online services actually believe that you own your personal data".

Contacts --------

Joseph Bonneau

phone: 01223 763793 mobile: 07590 677117

Jonathan Anderson

phone: 01223 763747 mobile: 07971 254416