The popularity of smart home devices is growing as consumers begin to recognize their potential to improve the quality of domestic life. At the same time, serious vulnerabilities have been revealed over recent years, which threaten user privacy and can cause financial losses. The lack of appropriate security protections in these devices is thus of increasing concern for the Internet of Things (IoT) industry, yet manufacturers’ ongoing efforts remain superficial. Hence, users continue to be exposed to serious weaknesses. In this paper, we demonstrate that this is also the case of home automation applications, as we uncover a set of previously undocumented security issues in the Belkin WeMo ecosystems. In particular, we first reverse engineer both the mobile app that enables users to control smart appliances and the communication logic implemented by WeMo devices. This enables us to compromise the passphrase guarding the communication over the local wireless network, opening the possibility of eavesdropping on user traffic. We further reveal how an attacker can present a fake device to a WeMo user, through which cross-site scripting can be exploited in order to mislead the user into disclosing private information. Lastly, we provide a set of security guidelines that can be followed to remedy the vulnerabilities identified.