Internet of Things (IoT) devices are nowadays widely used in individual homes and factories. Securing these new systems becomes a priority. However, conducting security audits of these connected objects based on experimental evaluation is a challenging task: it requires the use of heterogeneous hardware components leading to a set of specialised software tools, generally incompatible with each other and often complex to use. In this paper, we present a security audit and penetration testing framework called Mirage. This framework, written in Python, is dedicated to the analysis of wireless communications commonly used by IoT devices, and provides a generic, modular, unified and low level audit environment that is easy to adapt to new protocols. The paper describes the software architecture of Mirage, its goals and main features, and presents a concrete example of security audit performed with this framework.