Towards a Threat Model for Vehicular Fog Computing Security is a huge challenge in vehicular networks due to the large size of the network, high mobility of nodes, and continuous change of network topology. These challenges are also applicable to the vehicular fog, which is a new computing paradigm in the context of vehicular networks. In vehicular fog computing, the vehicles serve as fog nodes. This is a promising model for latencysensitive and locationaware services, which also incurs some unique security and privacy issues. However, there is a lack of a systematic approach to design security solutions of the vehicular fog using a comprehensive threat model. Threat modeling is a stepbystep process to analyze, identify, and prioritize all the potential threats and vulnerabilities of a system and solve them with known security solutions. A welldesigned threat model can help to understand the security and privacy threats, vulnerabilities, requirements, and challenges along with the attacker model, the attack motives, and attacker capabilities. Threat model analysis in vehicular fog computing is critical because only brainstorming and threat models of other vehicular network paradigms will not provide a complete scenario of potential threats and vulnerabilities. In this paper, we have explored the threat model of vehicular fog computing and identified the threats and vulnerabilities using STRIDE and CIAA threat modeling processes. We posit that this initiative will help to improve the security and privacy system design of vehicular fog computing.

Towards a Threat Model for Fog Computing In recent years, the addition of billions of Internet of Thing (IoT) device spawned a massive demand for computing service near the edge of the network. Due to latency, limited mobility, and location awareness, cloud computing is not capable enough to serve these devices. As a result, the focus is shifting more towards distributed platform service to put ample computing power near the edge of the networks. Thus, paradigms such as Fog and Edge computing are gaining attention from researchers as well as business stakeholders. Fog computing is a new computing paradigm, which places computing nodes in between the Cloud and the end user to reduce latency and increase availability. As an emerging technology, Fog computing also brings newer security challenges for the stakeholders to solve. Before designing the security models for Fog computing, it is better to understand the existing threats to Fog computing. In this regard, a thorough threat model can significantly help to identify these threats. Threat modeling is a sophisticated engineering process by which a computerbased system is analyzed to discover security flaws. In this paper, we applied two popular security threat modeling processes  CIAA and STRIDE  to identify and analyze attackers, their capabilities and motivations, and a list of potential threats in the context of Fog computing. We posit that such a systematic and thorough discussion of a threat model for Fog computing will help security researchers and professionals to design secure and reliable Fog computing systems.