Smart homes contain diverse sensors and actuators controlled by IoT apps that provide custom automation. Prior works showed that an adversary could exploit physical interaction vulnerabilities among apps and put the users and environment at risk, e.g., to break into a house, an adversary turns on the heater to trigger an app that opens windows when the temperature exceeds a threshold. Currently, the safe behavior of physical interactions relies on either app code analysis or dynamic analysis of device states with manually derived policies by developers. However, existing works fail to achieve sufficient breadth and fidelity to translate the app code into their physical behavior or provide incomplete security policies, causing poor accuracy and false alarms. In this paper, we introduce a new approach, IoTSeer, which efficiently combines app code analysis and dynamic analysis with new security policies to discover physical interaction vulnerabilities. IoTSeer works by first translating sensor events and actuator commands of each app into a physical execution model (PeM) and unifying PeMs to express composite physical execution of apps (CPeM). CPeM allows us to deploy IoTSeer in different smart homes by defining its execution parameters with minimal data collection. IoTSeer supports new security policies with intended/unintended physical channel labels. It then efficiently checks them on the CPeM via falsification, which addresses the undecidability of verification due to the continuous and discrete behavior of IoT devices. We evaluate IoTSeer in an actual house with 14 actuators, six sensors, and 39 apps. IoTSeer discovers 16 unique policy violations, whereas prior works identify only 2 out of 16 with 18 falsely flagged violations. IoTSeer only requires 30 mins of data collection for each actuator to set the CPeM parameters and is adaptive to newly added, removed, and relocated devices. 
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                            Detecting and Handling IoT Interaction Threats in Multi-Platform Multi-Control-Channel Smart Homes
                        
                    
    
            A smart home involves a variety of entities, such as IoT devices, automation applications, humans, voice assistants, and companion apps. These entities interact in the same physical environment, which can yield undesirable and even hazardous results, called IoT interaction threats. Existing work on interaction threats is limited to considering automation apps, ignoring other IoT control channels, such as voice commands, companion apps, and physical operations. Second, it becomes increasingly common that a smart home utilizes multiple IoT platforms, each of which has a partial view of device states and may issue conflicting commands. Third, compared to detecting interaction threats, their handling is much less studied. Prior work uses generic handling policies, which are unlikely to fit all homes. We present IoTMediator, which provides accurate threat detection and threat-tailored handling in multi-platform multi-control-channel homes. Our evaluation in two real-world homes demonstrates that IoTMediator significantly outperforms prior state-of-the-art work. 
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                            - PAR ID:
- 10499393
- Publisher / Repository:
- USENIX
- Date Published:
- Journal Name:
- 32nd USENIX Security Symposium (USENIX Security 23)
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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