In VANETs, the DoS attacks could also disturb the communication by flooding the channels with repeated messages. However, the problem lies mainly with the DDoS attacks due to their widespread impacts. The study introduces a new intrusion detection and prevention system called “FireCol.” It is aimed at detecting and mitigating flood-based DDoS attacks within collaborative VANET networks. The proposed system integrates the ISP-level mechanism of detecting DDoS attacks close to their source and the DGSOT algorithm, which improves the detection capabilities by dynamically analyzing trustworthiness. FireCol works by creating virtual security rings around subscribers through collaborating Intrusion Prevention Systems (IPSs). The simulation results conducted in NS2 show that the firegroup system fully and reliably detects and prevents flooding-based DDoS attacks thus maintaining the resilience of the network and preventing the potential threats. The integration of DGSOT with FireCol noticeably and robustly enhances the system's attack identification capabilities, thus bringing very promising results in enhancing the security level of VANET networks.