The rapid development of the digital age has been pushing people to access a mobile working environment when handsets are becoming more diverse and convenient with the help of Virtualization Technology. The speed and usability of Virtualization Technology are astounding for saving initial investment costs and optimizing IT infrastructure. Such Virtualization Technology is what businesses are interested in and makes the virtual server market growing strongly, especially for businesses that have many branches. However, virtual systems (hypervisors) are more vulnerable than traditional servers according due to many network attacks from curious users. Therefore, it's necessary to prepare for the worst circumstances, understand clearly, and research for new threats that can break down the virtual system. In this paper, we attempt to demonstrate the TCP ACK storm based DoS (Denial of Service) attack on virtual and Docker networks to show the threats that easily are happen on services deploying on virtual networks. Based on such consequence, we propose some solutions to prevent our virtual system from potential risks.