Connected transportation systems in smart cities can be regarded as Cyber-Physical-Social Systems (CPSSs) or Socio-Technical Systems (STSs) due to the presence of connectivity and complex interaction between human and technological infrastructure. Safety and security are essential requirements for such transportation CPSS. Specifically, resilience against cyber-attacks is crucial to address the vulnerabilities of Information and Communication Technologies (ICT) within the infrastructure. In this work, we explore a cyber-attack detection paradigm that leverages the socio-technical nature of such transportation CPSS. Essentially, we exploit the redundancies between physical signals (received from vehicle and infrastructure sensors) and social signals (received from consumers’ mobile devices and social media) to detect cyber-attack occurrences. The proposed scheme is developed combining system and control theoretic tools and natural language processing techniques. A case study of a vehicular platoon is considered on which extensive simulation studies have been performed. Such simulation results under different types of cyber-attacks illustrate the promising nature of the proposed approach.