On covert channels between virtual machines

Abstract

Virtualization technology has become very popular because of better hardware utilization and easy maintenance. However, there are chances for information leakage and possibilities of several covert channels for information flow between the virtual machines. Our work focuses on the experimental study of security threats in virtualization, especially due to covert channels and other forms of information leakage. The existence of data leakage during migration shutdown and destruction of virtual machines, is tested on different hypervisors. For empirically showing the possibility of covert channels between virtual machines, three new network based covert channels are hypothesized and demonstrated through implementation, on different hypervisors. One of the covert channels hypothesized is a TCP/IP steganography based covert channel. Other covert channels are a timing covert channel and a new network covert channel having two pairs of socket programs. We propose a VMM (Virtual Machine Monitor) based network covert channel avoidance mechanism, tackling detection resistant covert channel problems. We also address issue of reducing the possibilities of network based covert channels using VMM-level firewalls. In order to emphasize the importance of addressing the issue of information leakage through virtual machines, we illustrate the simplicity of launching network covert channel based attacks, by demonstrating an attack on a virtual machine using covert channels through implementation.