Anonymous use of Social network do not prevent users from privacy risks resulting from infering and cross-checking information published by themselves or their relationhips. With this in mind we have conducted a survey in order to measure sensitiveness of personal data published on social media and to analyze the users behaviors. We have shown that 76 % of internet users that have answered the survey are vulnerable to identity or sensitive data disclosure. Our study is completed by the description of an automatic procedure that shows how easily these vulnerabilities can be exploited and motivates the need for more advanced protection mechanisms.