On the feasibility of covert channels through Short-Message-Service

Short-Message-Service (SMS) is one of the most used ways to exchange text messages offered by mobile networks. In this paper, we explore the feasibility of establishing a tunneling system based on SMS. Our proposed scheme allows a client (e.g. a web browser) to connect to the Internet by encapsulating HTTP/HTTPS requests/responses into SMS messages. Along with the development of the tunneling architecture and the attack modelling, we conducted some preliminary tests to evaluate the feasibility of the proposed tunneling system. Obtained results indicate that our system is able to handle up to 1920 bytes of web request data when using equal mobile operators, whereas 1248 bytes for different mobile operators.