TenantGuard: Scalable Runtime Verification of Cloud-Wide VM-Level Network Isolation

Abstract

Multi-tenancy in the cloud usually leads to security concerns over network isolation around each cloud tenant's virtual resources. However, verifying network isolation in cloud virtual networks poses several unique challenges. The sheer size of virtual networks implies a prohibitive complexity, whereas the constant changes in virtual resources demand a short response time. To make things worse, such networks typically allow fine-grained (e.g., VM-level) and distributed (e.g., security groups) network access control. Those challenges can either invalidate existing approaches or cause an unacceptable delay which prevents runtime applications. In this paper, we present TenantGuard, a scalable system for verifying cloud-wide, VMlevel network isolation at runtime. We take advantage of the hierarchical nature of virtual networks, efficient data structures, incremental verification, and parallel computation to reduce the performance overhead of security verification. We implement our approach based on OpenStack and evaluate its performance both in-house and on Amazon EC2, which confirms its scalability and efficiency (13 seconds for verifying 168 millions of VM pairs). We further integrate TenantGuard with Congress, an OpenStack policy service, to verify compliance with respect to isolation requirements based on tenant-specific high-level security policies. Permission to freely reproduce all or part of this paper for noncommercial purposes is granted provided that copies bear this notice and the full citation on the first page. Reproduction for commercial purposes is strictly prohibited without the prior written consent of the Internet Society, the first-named author (for reproduction of an entire paper only), and the author's employer if the paper was prepared within the scope of employment.

Network Services Anomalies in NFV: Survey, Taxonomy, and Verification Methods

“…The regression test suit avoids enforcing policies that may introduce security vulnerabilities or availability issues in the network. Other works [85], [71], [89], [90] concentrate on monitoring the network configuration changes to detect change events that introduce security failures.…”

<i>Verikube</i>: Automatic and Efficient Verification for Container Network Policies

“…Cloud providers are responsible for manually writing available and secure network policies that are thus error-prone. Existing works such as NoD [3], Plotkin et al [4], Cloud Radar [5], Probst et al, [6] and Tenant-Guard [7] proposed several methods for verifying policies formatted routing rules.…”