# An Access Control Model for Preventing Virtual Machine Hopping Attack
## 2 Related Works  
Cloud computing and traditional IT technologies have different service models, operating modes, forms of information exchange, and technologies that provide cloud services, which makes cloud computing face different threats and risks from traditional IT technologies. Virtualization plays an important role in the construction of cloud computing. However, there are various vulnerabilities in current virtualization implementations, and the virtualization layer [6] faces various security challenges. With the help of network virtualization, a single network infrastructure can be divided into several virtual architectures. This benefits a wide range of applications, including cloud computing infrastructures. In [7], [PERSON] et al. discussed several main challenges and threats related to the virtual network security, and presented the corresponding solutions, as well as the security aspects that had not yet been approached. In a cloud environment, security is vital to detecting intrusions into the virtual network layer. [PERSON] et al. [8] proposed a hybrid intrusion detection system (H-IDS) to monitor security in a virtual network layer, but they did not deploy and verify the experiment. The security problems in virtualization can be divided into two categories: Virtualization security risks and virtualization security attacks. Common virtualization attacks [9] include virtual machine stealing and tampering, virtual machine hopping, virtual machine escape, virtual-machine based rootkit (VMBR) attacks, and denial of service attacks. Based on the BLP model, [PERSON] et al. [10] proposed PVME to prevent virtual machine escape from the aspects of access control. They added two new access properties (execute (e*) and control (c*)) to the PVME model and formulated several rules for different VM states. [PERSON] et al. [11] showed that the virtual switch itself can retransmit TCPpackets, which can be abused for amplification attacks by internal attackers. [PERSON] et al. [12] presented a new classification of malware attacks in IaaS cloud environments, which helps practitioners at early stages of the design of virtual machine introspection based mitigation mechanisms by identifying relevant attacks. Central to the cloud environment is virtualization technology, the core of which is the virtual machine (VM). Therefore, the communication capabilities between VMs are paramount. For cloud users, poor VM communication extends tenant tasks and VM lease time, eventually increasing their costs. On the other hand, the poor communication between VMs also introduces security vulnerabilities [13]. [PERSON] et al. [14] outlined security challenges that exist in virtualization techniques and which are used to support several customers on one shared physical infrastructure. [PERSON] et al. [15] analyzed the security threats and challenges virtual machines faced and presented several typical attacks to virtual machine on the Xen platform. [PERSON] et al. [16] proposed a new three-layer security architecture, which is composed of virtual switch, virtual firewall, and VLANs, to prevent attacks to virtual machines, such as sniffing, spoofing, and mac flooding. [PERSON] et al. [17] introduced a trusted model for VM security in cloud computing. They encrypted the VM images and used snapshot technique and a third-party monitor, all of which improves the confidentiality, integrity, and availability of VM in cloud. [PERSON] et al. [18] presented an approach to efficiently detect side-channel attacks based on cross-VM cache, using hardware fine-grained information provided by Intel Cache Monitoring Technology (CMT) and Hardware Performance Counters (HPCs). These studies on virtualization security have achieved relatively satisfying results in virtualization security prevention. However, when focusing on the problem of virtual machine hopping attack, these studies are relatively one-sided and do not solve this problem well.