Social Media Site (SMS) usage has grown rapidly in the last few years. This sudden increase in SMS usage creates an opportunity for data leakage which could compromise personal and/or professional life. In this work, we have reviewed traditional penetration testing process and discussed the failures of traditional penetration testing process to test the 'People' layer of Simple Enterprise Security Architecture (SESA) model. In order to overcome these failures, we have developed the conceptual idea of online SMS user account penetration testing system that could be applied to online SMS user account and the user account could be categorised based on the rating points. This could help us to avoid leaking information that is sensitive and/or damage their reputation. Finally, we have also listed the best practice guidelines of online SMS usage.