Modern wireless communications systems are constantly evolving and growing more complex. Recently, there has been a shift towards software defined radios due to the flexibility soft- ware implementations provide. This enables an easier development process, longer product lifetimes, and better adaptability for congested environments than conventional hardware systems. However, this shift introduces new attack surfaces where vulnerable implementa- tions can be exploited to disrupt communications or gain unauthorized access to a system. Previous research concerning wireless security mainly focuses on vulnerabilities within pro- tocols rather than in the radios themselves. This dissertation specifically addresses this new threat against software radios and introduces a new security model intended to mitigate this threat. We also demonstrate example exploits of waveforms which can result in either a denial-of-service or a compromise of the system from a wireless attack vector. These example exploits target vulnerabilities such as overflows, unsanitized control inputs, and unexpected state changes.
We present a defense-in-depth security architecture for software radios that protects the system by isolating components within a waveform into different security zones. Exploits against vulnerabilities within blocks are contained by isolation zones which protects the rest of the system from compromise. This architecture is inspired by the concept of a microkernel and provides a minimal trusted computing base for developing secure radio systems. Unlike other previous security models, our model protects from exploits within the radio protocol stack itself and not just the higher layer application. Different isolation mechanisms such as containers or virtual machines can be used depending on the security risk imposed by a component and any security requirements. However, adding these isolation environments incurs a performance overhead for applications. We perform an analysis of multiple example waveforms to characterize the impact of isolation environments on the overall performance of an application and demonstrate the overhead generated from the added isolation can be minimal. Because of this, our defense-in-depth architecture should be applied to real-world, production systems. We finally present an example integration of the model within the GNU Radio framework that can be used to develop any waveform using the defense-in-depth se- curity architecture. / Doctor of Philosophy / In recent years, wireless devices and communication systems have become a common part of everyday life. Mobile devices are constantly growing more complex and with the growth in mobile networks and the Internet of Things, an estimated 20 billion devices will be connected in the next few years. Because of this complexity, there has been a recent shift towards using software rather than hardware for the primary functionality of the system. Software enables an easier and faster development process, longer product lifetimes through over- the-air updates, and better adaptability for extremely congested environments. However, these complex software systems can be susceptible to attack through vulnerabilities in the radio interfaces that allow attackers to completely control a targeted device. Much of the existing wireless security research only focuses on vulnerabilities within different protocols rather than considering the possibility of vulnerabilities in the radios themselves. This work specifically focuses on this new threat and demonstrates example exploits of software radios. We then introduce a new security model intended to protect against these attacks.
The main goal of this dissertation is to introduce a new defense-in-depth security architecture for software radios that protects the system by isolating components within a waveform into different security zones. Exploits against the system are contained within the zones and unable to compromise the overall system. Unlike other security models, our model protects from exploits within the radio protocol stack itself and not just the higher layer application. Different isolation mechanisms such as containers or virtual machines can be used depending on the security risk imposed by a component and any security requirements for the system. However, adding these isolation environments incurs a performance overhead for applications. We also perform a performance analysis with several example applications and show the overhead generated from the added isolation can be minimal. Therefore, the defense-in-depth model should be the standard method for architecting wireless communication systems. We finally present a GNU Radio based framework for developing waveforms using the defense- in-depth approach.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/96594 |
| Date | 27 January 2020 |
| Creators | Hitefield, Seth D. |
| Contributors | Electrical and Computer Engineering, Clancy, Thomas Charles III, Butt, Ali R., MacKenzie, Allen B., Black, Jonathan T., Yang, Yaling |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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