A Forensic Analysis of Images on Online Social Networks

The Web 3.0 is approaching fast and the Online Social Networks (OSNs) are becoming more and more pervasive in today daily activities. A subsequent consequence is that criminals are running at the same speed as technology and most of the time highly sophisticated technological machineries are used by them. Images are often involved in illicit or illegal activities, with it now being fundamental to try to ascertain as much as information on a given image as possible. Today, most of the images coming from the Internet flow through OSNs. The paper analyzes the characteristics of images published on some OSNs. The analysis mainly focuses on how the OSN processes the uploaded images and what changes are made to some of the characteristics, such as JPEG quantization table, pixel resolution and related metadata. The experimental analysis was carried out in June-July 2011 on Facebook, Badoo and Google+. It also has a forensic value: it can be used to establish whether an image has been downloaded from an OSN or not.