Passwords in the Air

Smart devices without an interactive UI (e.g., a smart bulb) typically rely on specific provisioning schemes to connect to wireless networks. Among all the provisioning schemes, SmartCfg is a popular technology to configure the connection between smart devices and wireless routers. Although the SmartCfg technology facilitates the Wi-Fi configuration, existing solutions seldom take into serious consideration the protection of credentials and therefore introduce security threats against Wi-Fi credentials. This paper conducts a security analysis against eight SmartCfg based Wi-Fi provisioning solutions designed by different wireless module manufacturers. Our analysis demonstrates that six manufacturers provide flawed SmartCfg implementations that directly lead to the exposure of Wi-Fi credentials: attackers could exploit these flaws to obtain important credentials without any substantial efforts on brute-force password cracking. Furthermore, we keep track of the smart devices that adopt such Wi-Fi provisioning solutions to investigate the influence of the security flaws on real world products. Through reversely analyzing the corresponding apps of those smart devices we conclude that the flawed SmartCfg implementations constitute a wide potential impact on the security of smart home ecosystems.