Home automation platforms provide a new level of convenience by enabling consumers to automate various aspects of physical objects in their homes. While the convenience is beneficial, security flaws in the platforms or integrated third-party products can have serious consequences for the integrity of a user's physical environment. In this paper we perform a systematic security evaluation of two popular smart home platforms, Google's Nest platform and Philips Hue, that implement home automation "routines" (i.e., trigger-action programs involving apps and devices) via manipulation of state variables in a centralized data store. Our semi-automated analysis examines, among other things, platform access control enforcement, the rigor of non-system enforcement procedures, and the potential for misuse of routines. This analysis results in ten key findings with serious security implications. For instance, we demonstrate the potential for the misuse of smart home routines in the Nest platform to perform a lateral privilege escalation, illustrate how Nest's product review system is ineffective at preventing multiple stages of this attack that it examines, and demonstrate how emerging platforms may fail to provide even bare-minimum security by allowing apps to arbitrarily add/remove other apps from the user's smart home. Our findings draw attention to the unique security challenges of platforms that execute routines via centralized data stores, and highlight the importance of enforcing security by design in emerging home automation platforms.
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Expat: Expectation-based Policy Analysis and Enforcement for Appified Smart-Home Platforms
This paper focuses on developing a security mechanism geared towards appified smart-home platforms. Such platforms often expose programming interfaces for developing automation apps that mechanize different tasks among smart sensors and actuators (e.g., automatically turning on the AC when the room temperature is above 80 F). Due to the lack of effective access control mechanisms, these automation apps can not only have unrestricted access to the user's sensitive information (e.g., the user is not at home) but also violate user expectations by performing undesired actions. As users often obtain these apps from unvetted sources, a malicious app can wreak havoc on a smart-home system by either violating the user's security and privacy, or creating safety hazards (e.g., turning on the oven when no one is at home). To mitigate such threats, we propose Expat which ensures that user expectations are never violated by the installed automation apps at runtime. To achieve this goal, Expat provides a platform-agnostic, formal specification language UEI for capturing user expectations of the installed automation apps' behavior. For effective authoring of these expectations (as policies) in UEI, Expat also allows a user to check the desired properties (e.g., consistency, entailment) of them; which due to their formal semantics can be easily discharged by an SMT solver. Expat then enforces UEI policies in situ with an inline reference monitor which can be realized using the same app programming interface exposed by the underlying platform. We instantiate Expat for one of the representative platforms, OpenHAB, and demonstrate it can effectively mitigate a wide array of threats by enforcing user expectations while incurring only modest performance overhead.
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- Award ID(s):
- 1657124
- NSF-PAR ID:
- 10162203
- Date Published:
- Journal Name:
- ACM Symposium on Access Control Models and Technologies
- Page Range / eLocation ID:
- 61 to 72
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Home automation platforms enable consumers to conveniently automate various physical aspects of their homes. However, the security flaws in the platforms or integrated third-party products can have serious security and safety implications for the user’s physical environment. This article describes our systematic security evaluation of two popular smart home platforms, Google’s Nest platform and Philips Hue, which implement home automation “routines” (i.e., trigger-action programs involving apps and devices) via manipulation of state variables in a centralized data store . Our semi-automated analysis examines, among other things, platform access control enforcement, the rigor of non-system enforcement procedures, and the potential for misuse of routines, and it leads to 11 key findings with serious security implications. We combine several of the vulnerabilities we find to demonstrate the first end-to-end instance of lateral privilege escalation in the smart home, wherein we remotely disable the Nest Security Camera via a compromised light switch app. Finally, we discuss potential defenses, and the impact of the continuous evolution of smart home platforms on the practicality of security analysis. Our findings draw attention to the unique security challenges of smart home platforms and highlight the importance of enforcing security by design.more » « less
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1145/3322431.3325107
