Social networking systems (SNS’s) such as Facebook are an ever evolving and developing means of social interaction, which is not only being used to disseminate information to family, friends and colleagues but as a way of meeting and interacting with "strangers" through the advent of a large number of social applications. The attractiveness of such software has meant a dramatic increase in the number of frequent users of SNS’s and the threats which were once common to the Internet have now been magnified, intensified and altered as the potential for criminal behaviour on SNS’s increases. Social networking sites including Facebook contain a vast amount of personal information, that if obtained could be used for other purposes or to carry out other crimes such as identity theft. This paper will focus on the security threats posed to social networking sites and gain an understanding of these risks by using a security approach known as “attack trees”. This will allow for a greater understanding of the complexity associated with protecting Social Networking systems with a particular focus on Facebook.<br /
