The majority of Internet subscriptions offered by French suppliers include a box allowing the user to take full advantage of all the services offered in their offer. This equipment can dramatically reduce the necessary technical knowledge to install Internet at home. To our knowledge, relatively few studies have analyzed the security of the ADSL BOX. This paper presents an innovative security analysis and methodology of the first results. As a first step, we propose a method to intercept and analyze all network protocols implemented at the start of a BOX ADSL. This method allowed us to perform a comparative study of different BOX used by French operators. The application of this method revealed a potential security issue for both of them. We present an experimental platform to exploit the weaknesses identified.