Activity 3 of the 2CeVau project was successfully completed. This activity aimed at performing vulnerability assessment, threat and attack modelling. The first milestone M5 of the activity was submitted to INEA and EC on the 31st of January 2020 with the tilttle “Μ5 – “Vulnerability analysis, Threat analysis and Attack modeling: focus on GR-BG-SRB 5G corridor use cases”. The report involved the complete assessment methodology applied in the use cases of the 5G corridor. It included the results of task 3.1, 3.2 and 3.3. The second milestone M6 of activity 3 was submitted to INEA and EC on the 31st of October 2020 with the tittle “Μ6 – Specification of Security controls and countermeasures (focus on GR-BG-SRB 5G corridor use cases).” The report contains a list of security services, controls and countermeasures that can be used to mitigate the threats and protect the system from possible attacks. It included the work of task 3.4.