This thesis considers information leakage in cloud virtually isolated networks. Virtual Network (VN) Isolation is a core element of cloud security yet research literature shows that no experimental work, to date, has been conducted to test, discover and evaluate VN isolation data leakage. Consequently, this research focussed on that gap. Deep Dives of the cloud infrastructures were performed, followed by (Kali) penetration tests to detect any leakage. This data was compared to information gathered in the Deep Dive, to determine the level of cloud network infrastructure being exposed. As a major contribution to research, this is the first empirical work to use a Deep Dive approach and a penetration testing methodology applied to both CloudStack and OpenStack to demonstrate cloud network isolation vulnerabilities. The outcomes indicated that Cloud manufacturers need to test their isolation mechanisms more fully and enhance them with available solutions. However, this field needs more industrial data to confirm if the found issues are applicable to non-open source cloud technologies. If the problems revealed are widespread then this is a major issue for cloud security. Due to the time constraints, only two cloud testbeds were built and analysed, but many potential future works are listed for analysing more complicated VN, analysing leveraged VN plugins and testing if system complexity will cause more leakage or protect the VN. This research is one of the first empirical building blocks in the field and gives future researchers the basis for building their research on top of the presented methodology and results and for proposing more effective solutions
