Privacy and Security for Multimedia Content shared on OSNs: Issues and Countermeasures

A key aspect of online social networks (OSNs) is the user-generated multimedia content shared online. OSNs like Facebook have to deal with up to 300 million photos uploaded on a daily basis, both video- and audio-related social networks have also started to gain important shares of the market. Although the security and privacy mechanisms deployed by OSNs can cope with several risks and discourage inexperienced users from malicious behaviours, many issues still need to be addressed. Uploaded multimedia content carries information that could be transmitted virally and almost instantaneously within OSNs and beyond. OSNs could be seen as a multimedia heaven for users. However, in many cases they might end up being the user's personal hell with information disclosure or distortion, contrary to his/her will. In this article, we outline the most significant security and privacy issues related to the exposure of multimedia content in OSNs and we discuss possible countermeasures.