Internet of Things (IoT) devices are becoming increasingly important. These devices are often resource-limited, hindering rigorous enforcement of security policies. Assessing the vulnerability of IoT devices is an important problem, but analyzing their firmware is difficult for a variety of reasons, including requiring the purchase of devices. This paper finds that analyzing companion apps to these devices for clues to security vulnerabilities can be an effective strategy. Compared to device hardware and firmware, these apps are easy to download and analyze. A key finding of this study is that the communication between an IoT device and its app is often not properly encrypted and authenticated and these issues enable the construction of exploits to remotely control the devices. To confirm the vulnerabilities found, we created exploits against five popular IoT devices from Amazon by using a combination of static and dynamic analyses. We also did a larger study, finding that analyzing 96 popular IoT devices only required analyzing 32 companion apps. Among the conservative findings, 50% of the apps corresponding to 38% of the devices did not use proper encryption techniques to secure device to companion app communication. Finally, we discuss defense strategies that developers can adapt to address the lessons from our work.
Security of Internet of Things (IoT) devices is a wellknown concern as these devices come in increasing use in homes and commercial environments. To better understand the extent to which companies take security of the IoT devices seriously and the methods they use to secure them, this paper presents findings from a security analysis of 96 top-selling WiFi IoT devices on Amazon. We found that we could carry out a significant portion of the analysis by first analyzing the code of Android companion apps responsible for controlling the devices. An interesting finding was that these devices used only 32 unique companion apps; we found instances of devices from same as well as different brands sharing the same app, significantly reducing our work. We analyzed the code of these companion apps to understand how they communicated with the devices and the security of that communication. We found security problems to be widespread: 50% of the apps corresponding to 38% of the devices did not use proper encryption techniques; some even used well-known weak ciphers such as Caesar cipher. We also purchased 5 devices and confirmed the vulnerabilities found with exploits. In some cases, we were able to bypass the pairing process and still control the device. Finally, we comment on technical and non-technical lessons learned from the study that have security implications.
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