Moving towards software-defined security in the era of NFV and SDN. (Vers une programmabilité de la sécurité dans les environnements réseaux logiciels et virtualisés (NFV et SDN))

This thesis is intended to explore security issues in the virtualized and software-defined world, and starts with two important hypotheses: (1) SDN and NFV offer plenty of opportunities for us to rethink security management in the new networking paradigms; (2) both legacy and new security threats and vulnerabilities in NFV/SDN enabled environments need to be sufficiently addressed in order to pave the way for their further development and deployment. To validate the hypotheses, we carry out an in-depth study on NFV/SDN from security perspective, including its architecture, management and orchestration (MANO) framework, and use cases, leading to two major contributions, (1) a security management and orchestration framework (called SecMANO) based on NFV MANO, which has the potential to manage a set of policy-driven security mechanisms, such as access control, IDS/IPS, network isolation, data protection; (2) a comprehensive threat analysis on five NFV use cases and the state-of-the-art security countermeasures, resulting in a NFV layer-specific threat taxonomy and a set of security recommendations on securing NFV based services.We believe that both of the two contributions lay down a foundation for security research in NFV/SDN domain. In particular, based on the two contributions, we further develop a security orchestrator as an extension of available NFV orchestrator, with an objective to enabling the basic security functions to be effectively orchestrated and provided as on-demand services to the customers, meanwhile allowing high-level security policies to be specified and enforced in a dynamic and flexible way. Specifically, a software-defined access control paradigm is implemented and prototyped with OpenStack and Tacker (a NFV orchestrator using TOSCA model), which allows the security administrators to dynamically customize the access control models and policies for different tenant domains, eventually achieving flexible and scalable protection across different layers and multiple cloud data centers. Both prototype of concept and real-life experiments on testbed have been carried out, clearly demonstrating the feasibility and effectiveness of our security orchestrator.In addition, as our NFV cross-layer threat taxonomy indicates, a large set of novel threats will be introduced, among which VNF (Virtualized Network Function) is a unique and important asset that deserves careful protection. The fourth contribution of this thesis is therefore devoted to achieving secure and dependable SFC (Service Function Chaining) in NFV and SDN environment. Specifically, an identity-based ordered multisignature scheme called SecSFC is designed and applied to ensure that, (1) each service function involved in a particular service chain is authenticated and legitimate; (2) all the service functions are chained in a consistent, optimal, and reliable way, meeting with the pre-defined high-level specifications like VNF Forwarding Graph. Both theoretical security analysis and experimental results demonstrate that our scheme can effectively defend against a large set of destructive attacks like rule modification and topology tempering, moving an important step towards secure and dependable SFC. Importantly, the signature construction and validation process is lightweight, generating compact and constant-size keys and signatures, thereby only incurring minimal computational overhead and latency