School of Computer and Information Science, Edith Cowan University, Perth, Western Australia
A Virtual Machine (VM) based secure Portable Execution Environment (PEE) provides a safe and secure environment that can be loaded into a host PC and an application executed with a degree of confidence that the application is separated, protected and little or no forensic evidence remains after the application has executed. A VM based secure PEE is characterised as a USB storage device containing a VM with a trusted guest operating system and application(s) which is stored in a protected partition, strong authentication to only allow an authorised user to load the VM into the host PC, and full storage device encryption to protect the confidentiality of the contents of the device. Secure PEEs provide an opportunity for organisations to issue a portable device to an individual (to perform a secure transaction on an available host PC) with the reduced risk to the organisation that neither malicious software (resident on the host PC) will infect the secure PEE device, nor sensitive data remnants (resulting from the transaction) will remain on the host PC hard disk drive after the secure PEE device has been removed. A VM based secure PEE significantly reduces the opportunity to use dead forensic analysis techniques to acquire evidence of the occurrence of a transaction. However, VM based secure PEEs are susceptible to the acquisition of data through monitoring software and live forensic techniques. This paper considers the mechanisms that can be used to prevent various monitoring and live forensic techniques acquiring data from a VM based secure PEE. An attack scenario is presented to provide the context for the analysis of VM based secure PEE device vulnerabilities and why it is important that such a device would be required to counter hostile monitoring and forensic analysis. An overview is given of the security mechanisms provided by the type of VM based secure PEE under consideration and how those mechanisms combine to limit the opportunity for data acquisition through dead forensic techniques. The vulnerabilities of VM based secure PEEs with respect to malicious software and live forensic techniques are enumerated and discussed. A comprehensive set of countermeasures are proposed and analysed. The paper concludes by considering the most appropriate countermeasures to include in a VM based secure PEE to prevent the live acquisition of data...