In the network security life cycle, security needs are initialized by network operators and typically documented in natural languages, and later implemented and deployed in developed/acquired security appliances, typically written in a programming language by third-party developers. However, oftentimes, those security appliances/programs may not quite match the urgent and fast-evolving security needs since the whole developing/deployment procedure is very time-consuming. In this paper, we propose a novel framework, AUTOSEC, to aid network operators in building up or rapid prototyping operational network security services directly from high-level service needs as automatically as possible. AUTOSEC helps bridge the huge gap from human intents in natural language descriptions to the deliverable network security services. More specifically, AUTOSEC utilizes Natural Language Processing (NLP) techniques to infer security intents from natural language descriptions, and then performs Interactive Synthesis to assist users to validate and refine parsed intents if necessary. AUTOSEC further lever-ages Software-Defined Networking (SDN) and Network Function Virtualization (NFV) techniques to automatically compose and instantiate security services in terms of refined security intents. In the evaluation, we demonstrate the early success of AUTOSEC with security policy descriptions collected from various data sources including research papers, appliance descriptions, real-world security standards, and human-written policies.

Zero Trust, as an emerging trend of cybersecurity paradigms in modern infrastructure (e.g., enterprise, cloud, edge, IoT, and 5G), is moving security defenses from static and perimeter-based control systems to focus on users and resources with no assumption of implicit trust. However, the current Zero Trust Architecture (ZTA) mainly focuses on the network security and lacks in-depth considerations on system-level security policies and abstractions, which leaves the realization of the principle incomplete. To bridge the gap, we propose an innovativeprogrammablesystem security framework called SYSFLOW to enable unified, dynamic, and fine-grained Zero Trust security control for system resources. SYSFLOW introduces a novelsystem flowabstraction to modelsystem activitiesacross the entire infrastructure, and provides a system-level data plane and control plane separation and abstraction. The new logically centralized controller accommodates a unifiedprogrammablePolicy Decision Point (PDP) that acquires a holistic view of system behaviors for controlling system resource accesses by translated programmable security policies into system flow rules. The SYSFLOW data plane, acting as Policy Enforcement Point (PEP), enforces translated system flow rules, which can be updated dynamically and facilitate fine-grained responsive actions. Our extensive evaluations demonstrate the effectiveness and scalability of SYSFLOW, which addresses the security issues in various scenarios with a minor performance overhead.

Software-Defined Networking (SDN) continues to be deployed spanning from enterprise data centers to cloud computing with the proliferation of various SDN-enabled hardware switches and dynamic control plane applications. However, state-of-the-art SDN-enabled hardware switches have rather limited downlink message processing capability, especially for Flow-Mod and Statistic Query, which may not suffice the huge need of dynamic control plane applications. In this paper, we systematically study the interactions between the control plane applications and the data plane switches, and present two new attacks, namely Control Plane Reflection Attacks, to exploit the limited processing capability of SDN-enabled hardware switches. The reflection attacks adopt direct and indirect data plane events to force the control plane to issue massive expensive downlink messages towards SDN switches. Moreover, we propose a two-phase probing-triggering attack strategy, which makes the reflection attacks much more efficient and powerful. Experiments on a testbed with 3 different physical OpenFlow switches demonstrate that the attacks can lead to catastrophic results such as hurting the establishment of new flows and even disruption of connection between SDN controller and switches. To mitigate such attacks, we present several countermeasures from different perspectives. In particular, we propose a novel, systematical defense framework, SwitchGuard, to detect anomalies of downlink messages and prioritize these messages based on a novel monitoring granularity, i.e., host-application pair (HAP). Implementations and evaluations demonstrate that SwitchGuard can effectively reduce the latency for legitimate hosts and applications under the control plane reflection attacks with only minor overheads.

Diagnosing network security issues in traditional networks is difficult. It is even more frustrating in the emerging Software Defined Networks. The data/control plane decoupling of the SDN framework makes the traditional network troubleshooting tools unsuitable for pinpointing the root cause in the control plane. In this paper, we propose ForenGuard, which provides flow-level forensics and diagnosis functions in SDN networks. Unlike traditional forensics tools that only involve either network level or host level, ForenGuard monitors and records the runtime activities and their causal dependencies involving both the SDN control plane and data plane. Starting with a forwarding problem (e.g., disconnection) which could be caused by a security issue, ForenGuard can backtrack the previous activities in both the control and data plane through causal relationships and pinpoint the root cause of the problem. ForenGuard also provides a user-friendly interface that allows users to specify the detection point and diagnose complicated network problems. We implement a prototype system of ForenGuard on top of the Floodlight controller and use it to diagnose several real control plane attacks. We show that ForenGuard can quickly display causal relationships of activities and help to narrow down the range of suspicious activities that could be the root causes. Our performance evaluation shows that ForenGuard will add minor runtime overhead to the SDN control plane and can scale well in various network workloads.

As Software-Defined Networking has gained increasing prominence, new attacks have been demonstrated which can corrupt the SDN controller's view of network topology. These topology poisoning attacks, most notably host-location hijacking and link fabrication attacks, enable adversaries to impersonate end-hosts or inter-switch links in order to monitor, corrupt, or drop network flows. In response, defenses have been developed to detect such attacks and raise an alert. In this paper, we analyze two such defenses, TopoGuard and Sphinx, and present two new attacks, Port Probing and Port Amnesia, that can successfully bypass them. We then develop and present extensions to TopoGuard to make it resilient to such attacks.

The need of customized network functions for enterprises in Infrastructure-as-a-Service (IaaS) clouds is emerging. However, existing network functions in IaaS clouds are very limited, inflexible, and hard to control by the tenants. Recently, the introduction of Software-Defined Networking (SDN) technology brings the hope of flexible control of network flows and creation of diverse network functions. Unfortunately, enterprises lose access to the SDN controller when they move to clouds. Moreover, the cloud SDN controller is only managed by the provider administrators for security and performance reasons. To allow enterprise tenants to develop and deploy their own SDN apps in the cloud, in this paper, we introduce a new cloud usage paradigm: Bring Your Own Controller (BYOC). BYOC offers each tenant an individual SDN controller, where tenants can deploy SDN apps to manage their network. To manage these tenant SDN controllers, we propose BYOC-Visor, a new SDN-based virtualization platform. BYOC-VISOR addresses several security and performance challenges which are specific to IaaS clouds. We show that BYOC-Visor supports different controller platforms and diverse SDN security applications such as firewall, IDS, and access control. We implement a prototype system and the performance evaluation results show that our system has low overhead.

Software Defined Networking (SDN) is an emerging technology that attracts significant attention from both industry and academia recently. By decoupling the control logic from the closed and proprietary implementations of traditional network devices, it enables researchers and practitioners to design new innovative network functions/protocols in a much more flexible, powerful, and easier way. We believe SDN provides new research opportunities to security, and it can greatly impact network security research in many different ways. However, till today, SDN has not been well recognized by the security community yet. In this systematic survey on SDN security, we investigate how the new features provided by SDN can help enhance network security and information security process. By systematically reasoning the opportunities introduced by SDN to network security, we hope to provide new insights for future research in this important area.

This paper addresses one serious SDN-specific attack, i.e., data-to-control plane saturation attack, which overloads the infrastructure of SDN networks. In this attack, an attacker can produce a large amount of table-miss packet_in messages to consume resources in both control plane and data plane. To mitigate this security threat, we introduce an efficient, lightweight and protocol-independent defense framework for SDN networks. Our solution, called FloodGuard, contains two new techniques/modules: proactive flow rule analyzer and packet migration. To preserve network policy enforcement, proactive flow rule analyzer dynamically derives proactive flow rules by reasoning the runtime logic of the SDN/OpenFlow controller and its applications. To protect the controller from being overloaded, packet migration temporarily caches the flooding packets and submits them to the OpenFlow controller using rate limit and round-robin scheduling. We evaluate FloodGuard through a prototype implementation tested in both software and hardware environments. The results show that FloodGuard is effective with adding only minor overhead into the entire SDN/OpenFlow infrastructure.