SODA: A software-defined security framework for IoT environments

Abstract

The Internet of Things (IoT), based on interconnected devices, enables a variety of elegant new services that could not be realized in a traditional environment, and many of these services harvest the information of a potentially sensitive and private nature belonging to individual users. Unfortunately, existing security functions used to protect such information are difficult to implement in an IoT environment due to the widely varying capacities, functionalities, and security requirements of IoT devices. In this work, to protect against unrestricted accesses to other devices and information extortion from these devices, we propose SODA, a secure IoT gateway that enables a device-side dynamic access control and is capable of deploying various security services to protect sensitive and private information. To show its effectiveness and practicality, we assume that a large number of IoT devices are crowded around an IoT gateway, and we implement a prototype of SODA for such an environment based on software-defined-networking (SDN) and integrate virtual network functions (VNFs) over network function virtualization (NFV) on top of a real IoT device. From our evaluation, we demonstrate how SODA mitigates real-world attacks through its security functions, and presents how it satisfies the performance requirements of a real environment.

Introduction

The Internet of Things (IoT) is an ecosystem in which devices (i.e., Things) are connected to a network (i.e., the Internet) such that these devices can communicate and share data with each other through the connected network. As this ecosystem provides powerful network connectivity of diverse IoT devices, it is rapidly increasing in popularity; this trend can be easily observed across industry and academia [7], [16], [18], [23], [34], [45]. For instance, smart watches are available today and already selling well [5]. Some IoT services have already been provided by commercial vendors (e.g., Apple Homekit [4] or Samsung SmartThings [35]).

However, an IoT environment that is composed of highly connected IoT devices also introduces critical security problems. For example, a compromised or malicious device can easily access other connected devices through an IoT network due to the lack of authentication and access control, and then be used to conduct various attacks on nearby devices, such as stealing private information from the devices. Thus, for those IoT devices that handle sensitive data (e.g., health information), the security problems of the IoT environment could be even more critical.

Security challenges in an IoT environment are often regarded as more complicated than those of legacy networks due to the diversity of IoT devices. In terms of security policies, IoT users have different security requirements for IoT devices; thus, each IoT device should maintain multiple security policies to satisfy their requirements. Unfortunately, those policies can cause unexpected policy and intent conflicts with each other. In addition, those policies can cause some other conflicts when multiple IoT devices access and control the same resources. With regard to security functionalities, when deploying security functions for IoT devices, we need to allocate resources to operate those functions efficiently. However, an IoT device is, in general, a lightweight, single-board computer with low computation power, which means that its functionality is restricted. Hence, we need to carefully consider how to operate necessary security functions with restricted resources as well. Although some pioneering researchers have proposed solutions for securing IoT environments [6], [17], [31], [34], [47], [48], none of them have addressed the combination of these security challenges.

Today’s network architecture for an IoT environment is broadly classified into two types: (i) peer-to-peer and (ii) centralized. In the former case, each IoT device directly connects to another device to share information; the AllJoyN project [23] is a good example for this case. In the case of the centralized type, IoT devices are connected to a centralized point (i.e., a gateway) for network services. While the peer-to-peer type is often used in these days, most vendors have adopted the centralized type because it can easily manage large-scale IoT devices through a centralized gateway that handles all network flows among the devices [7], [18]. Following today’s trend, we focus on a centralized IoT network to address security challenges in an IoT environment.

In this paper, we present a novel security framework, called SODA, to realize centralized security policy and service management for IoT environments (specifically, for the IoT environment where a large number of IoT devices are crowded around a centralized IoT gateway). In our proposal, all IoT devices are connected to SODA, and all security policies (e.g., who can communicate with whom) are controlled by SODA. In addition, SODA provides the capability of deploying various security services, such as intrusion prevention system and botnet mitigation, and each user (or IoT device) can dynamically take some of security services on request. Security services supported by SODA can be classified into two types: (i) network access control and (ii) network security functions. First, SODA controls (either blocks or allows) network accesses among IoT users and devices according to dynamically defined security policies. Second, SODA provides more complex security capabilities. For example, let us assume that a malicious device (perhaps infected by an attacker) tries to compromise other linked devices. To prevent this, a network intrusion detection system should be activated and be available to target devices in the IoT network. SODA identifies this kind of a requirement and provides relevant security services using virtual network functions realized in SODA.

To implement a prototype of SODA, we leverage software defined networking (SDN) to control network flows among IoT devices [24], and network function virtualization (NFV) [10] to realize security functions inside of a centralized gateway. Then, we demonstrate how SODA can effectively and efficiently protect an IoT network through the prototype of SODA, and our evaluation results show that SODA can successfully enforce user-defined security policies while minimizing conflicts among policies and operating diverse network security functions with reasonable performance.

This paper is organized as follows. Section 2 discusses IoT security issues with an example of commercial IoT devices, and Section 3 presents a new security framework that addresses those issues while its core functionality is elaborated in Section 4. Section 5 describes its prototypical implementation, and Sections 6 and 7 demonstrate its effectiveness and practicality. Section 8 reviews the previous studies related to IoT security. Sections 9 and 10 conclude the paper while providing some leads for future works.