Biblio

Supervisory Control and Data Acquisition(SCADA) communications are often subjected to various sophisticated cyber-attacks mostly because of their static system characteristics, enabling an attacker for easier profiling of the target system(s) and thereby impacting the Critical Infrastructures(CI). In this Paper, a novel approach to mitigate such static vulnerabilities is proposed by implementing a Moving Target Defense (MTD) strategy in a power grid SCADA environment, leveraging the existing communication network with an end-to-end IP-Hopping technique among trusted peers. The main contribution involves the design and implementation of MTD Architecture on Iowa State's PowerCyber testbed for targeted cyber-attacks, without compromising the availability of a SCADA system and studying the delay and throughput characteristics for different hopping rates in a realistic environment. Finally, we study two cases and provide mitigations for potential weaknesses of the proposed mechanism. Also, we propose to incorporate port mutation to further increase attack complexity as part of future work.

This paper will suggest a robust method for a network layer Moving Target Defense (MTD) using symmetric packet scheduling rules. The MTD is implemented and tested on a Supervisory Control and Data Acquisition (SCADA) network testbed. This method is shown to be efficient while providing security benefits to the issues faced by the static nature of SCADA networks. The proposed method is an automated tool that may provide defense in depth when be used in conjunction with other MTDs and traditional security devices.

Among the several threats to cyber services Distributed denial-of-service (DDoS) attack is most prevailing nowadays. DDoS involves making an online service unavailable by flooding the bandwidth or resources of a targeted system. It is easier for an insider having legitimate access to the system to circumvent any security controls thus resulting in insider attack. To mitigate insider assisted DDoS attacks, this paper proposes a moving target defense mechanism that involves isolation of insiders from innocent clients by using attack proxies. Further using the concept of load balancing an effective algorithm to detect and handle insider attack is developed with the aim of maximizing attack isolation while minimizing the total number of proxies used.

In order to support large volume of transactions and number of users, as estimated by the load demand modeling, a system needs to scale in order to continue to satisfy required quality attributes. In particular, for systems exposed to the Internet, scaling up may increase the attack surface susceptible to malicious intrusions. The new proactive approach based on the concept of Moving Target Defense (MTD) should be considered as a complement to current cybersecurity protection. In this paper, we analyze the scalability of the Self Cleansing Intrusion Tolerance (SCIT) MTD approach using Cloud infrastructure services. By applying the model of MTD with continuous rotation and diversity to a multi-node or multi-instance system, we argue that the effectiveness of the approach is dependent on the share-nothing architecture pattern of the large system. Furthermore, adding more resources to the MTD mechanism can compensate to achieve the desired level of secure availability.

Consensus is a fundamental approach to implementing fault-tolerant services through replication. It is well known that there exists a tradeoff between the cost and the resilience. For instance, Crash Fault Tolerant (CFT) protocols have a low cost but can only handle crash failures while Byzantine Fault Tolerant (BFT) protocols handle arbitrary failures but have a higher cost. Hybrid protocols enjoy the benefits of both high performance without failures and high resiliency under failures by switching among different subprotocols. However, it is challenging to determine which subprotocols should be used. We propose a moving target approach to switch among protocols according to the existing system and network vulnerability. At the core of our approach is a formalized cost model that evaluates the vulnerability and performance of consensus protocols based on real-time Intrusion Detection System (IDS) signals. Based on the evaluation results, we demonstrate that a safe, cheap, and unpredictable protocol is always used and a high IDS error rate can be tolerated.

As the use of wireless technologies increases significantly due to ease of deployment, cost-effectiveness and the increase in bandwidth, there is a critical need to make the wireless communications secure, and resilient to attacks or faults (malicious or natural). Wireless communications are inherently prone to cyberattacks due to the open access to the medium. While current wireless protocols have addressed the privacy issues, they have failed to provide effective solutions against denial of service attacks, session hijacking and jamming attacks. In this paper, we present a resilient wireless communication architecture based on Moving Target Defense, and Software Defined Radios (SDRs). The approach achieves its resilient operations by randomly changing the runtime characteristics of the wireless communications channels between different wireless nodes to make it extremely difficult to succeed in launching attacks. The runtime characteristics that can be changed include packet size, network address, modulation type, and the operating frequency of the channel. In addition, the lifespan for each configuration will be random. To reduce the overhead in switching between two consecutive configurations, we use two radio channels that are selected at random from a finite set of potential channels, one will be designated as an active channel while the second acts as a standby channel. This will harden the wireless communications attacks because the attackers have no clue on what channels are currently being used to exploit existing vulnerability and launch an attack. The experimental results and evaluation show that our approach can tolerate a wide range of attacks (Jamming, DOS and session attacks) against wireless networks.

While existing proactive-based paradigms such as address mutation are effective in slowing down reconnaissance by naive attackers, they are ineffective against skilled human attackers. In this paper, we analytically show that the goal of defeating reconnaissance by skilled human attackers is only achievable by an integration of five defensive dimensions: (1) mutating host addresses, (2) mutating host fingerprints, (3) anonymizing host fingerprints, (4) deploying high-fidelity honeypots with context-aware fingerprints, and (5) deploying context-aware content on those honeypots. Using a novel class of honeypots, referred to as proxy honeypots (high-interaction honeypots with customizable fingerprints), we propose a proactive defense model, called (HIDE), that constantly mutates addresses and fingerprints of network hosts and proxy honeypots in a manner that maximally anonymizes identity of network hosts. The objective is to make a host untraceable over time by not letting even skilled attackers reuse discovered attributes of a host in previous scanning, including its addresses and fingerprint, to identify that host again. The mutations are generated through formal definition and modeling the problem. Using a red teaming evaluation with a group of white-hat hackers, we evaluated our five-dimensional defense model and compared its effectiveness with alternative and competing scenarios. These experiments as well as our analytical evaluation show that by anonymizing all identifying attributes of a host/honeypot over time, HIDE is able to significantly complicate reconnaissance, even for highly skilled human attackers.

The moving network target defense (MTD) based approach to security aims to design and develop capabilities to dynamically change the attack surfaces to make it more difficult for attackers to strike. One such capability is to dynamically change the IP addresses of subnetworks in unpredictable ways in an attempt to disrupt the ability of an attacker to collect the necessary reconnaissance information to launch successful attacks. In particular, Denial of Service (DoS) and worms represent examples of distributed attacks that can potentially propagate through networks very quickly, but could also be disrupted by MTD. Conversely, MTD are also disruptive to regular users. For example, when IP addresses are changed dynamically it is no longer effective to use DNS caches for IP address resolutions before any communication can be performed. In this work we take another approach. We note that the deployment of MTD could be triggered through the use of light-weight intrusion detection. We demonstrate that the neuro-evolution of augmented topologies algorithm (NEAT) has the capacity to construct detectors that operate on packet data and produce sparse topologies, hence are real-time in operation. Benchmarking under examples of DoS and worm attacks indicates that NEAT detectors can be constructed from relatively small amounts of data and detect attacks approx. 90% accuracy. Additional experiments with the open-ended evolution of code modules through genetic program teams provided detection rates approaching 100%. We believe that adopting such an approach to MTB a more specific deployment strategy that is less invasive to legitimate users, while disrupting the actions of malicious users.

prevent attackers from gaining control of the system using well established techniques such as; perimeter-based fire walls, redundancy and replications, and encryption. However, given sufficient time and resources, all these methods can be defeated. Moving Target Defense (MTD), is a defensive strategy that aims to reduce the need to continuously fight against attacks by disrupting attackers gain-loss balance. We present Mayflies, a bio-inspired generic MTD framework for distributed systems on virtualized cloud platforms. The framework enables systems designed to defend against attacks for their entire runtime to systems that avoid attacks in time intervals. We discuss the design, algorithms and the implementation of the framework prototype. We illustrate the prototype with a quorum-based Byzantime Fault Tolerant system and report the preliminary results.

Botnets are increasingly being used for exfiltrating sensitive data from mission-critical systems. Research has shown that botnets have become extremely sophisticated and can operate in stealth mode by minimizing their host and network footprint. In order to defeat exfiltration by modern botnets, we propose a moving target defense approach for dynamically deploying detectors across a network. Specifically, we propose several strategies based on centrality measures to periodically change the placement of detectors. Our objective is to increase the attacker's effort and likelihood of detection by creating uncertainty about the location of detectors and forcing botmasters to perform additional actions in an attempt to create detector-free paths through the network. We present metrics to evaluate the proposed strategies and an algorithm to compute a lower bound on the detection probability. We validate our approach through simulations, and results confirm that the proposed solution effectively reduces the likelihood of successful exfiltration campaigns.

In today's enterprise networks, there are many ways for a determined attacker to obtain a foothold, bypass current protection technologies, and attack the intended target. Over several years we have developed the Self-shielding Dynamic Network Architecture (SDNA) technology, which prevents an attacker from targeting, entering, or spreading through an enterprise network by adding dynamics that present a changing view of the network over space and time. SDNA was developed with the support of government sponsored research and development and corporate internal resources. The SDNA technology was purchased by Cryptonite, LLC in 2015 and has been developed into a robust product offering called Cryptonite NXT. In this paper, we describe the journey and lessons learned along the course of feasibility demonstration, technology development, security testing, productization, and deployment in a production network.

Modern cyber systems and their integration with the infrastructure has a clear effect on the productivity and quality of life immensely. Their involvement in our daily life elevate the need for means to insure their resilience against attacks and failure. One major threat is the software monoculture. Latest research work demonstrated the danger of software monoculture and presented diversity to reduce the attack surface. In this paper, we propose ChameleonSoft, a multidimensional software diversity employment to, in effect, induce spatiotemporal software behavior encryption and a moving target defense. ChameleonSoft introduces a loosely coupled, online programmable software-execution foundation separating logic, state and physical resources. The elastic construction of the foundation enabled ChameleonSoft to define running software as a set of behaviorally-mutated functionally-equivalent code variants. ChameleonSoft intelligently Shuffle, at runtime, these variants while changing their physical location inducing untraceable confusion and diffusion enough to encrypt the execution behavior of the running software. ChameleonSoft is also equipped with an autonomic failure recovery mechanism for enhanced resilience. In order to test the applicability of the proposed approach, we present a prototype of the ChameleonSoft Behavior Encryption (CBE) and recovery mechanisms. Further, using analysis and simulation, we study the performance and security aspects of the proposed system. This study aims to assess the provisioned level of security by measuring the avalanche effect percentage and the induced confusion and diffusion levels to evaluate the strength of the CBE mechanism. Further, we compute the computational cost of security provisioning and enhancing system resilience.

Modern cyber systems and their integration with the infrastructure has a clear effect on the productivity and quality of life immensely. Their involvement in our daily life elevate the need for means to insure their resilience against attacks and failure. One major threat is the software monoculture. Latest research work demonstrated the danger of software monoculture and presented diversity to reduce the attack surface. In this paper, we propose ChameleonSoft, a multidimensional software diversity employment to, in effect, induce spatiotemporal software behavior encryption and a moving target defense. ChameleonSoft introduces a loosely coupled, online programmable software-execution foundation separating logic, state and physical resources. The elastic construction of the foundation enabled ChameleonSoft to define running software as a set of behaviorally-mutated functionally-equivalent code variants. ChameleonSoft intelligently Shuffle, at runtime, these variants while changing their physical location inducing untraceable confusion and diffusion enough to encrypt the execution behavior of the running software. ChameleonSoft is also equipped with an autonomic failure recovery mechanism for enhanced resilience. In order to test the applicability of the proposed approach, we present a prototype of the ChameleonSoft Behavior Encryption (CBE) and recovery mechanisms. Further, using analysis and simulation, we study the performance and security aspects of the proposed system. This study aims to assess the provisioned level of security by measuring the avalanche effect percentage and the induced confusion and diffusion levels to evaluate the strength of the CBE mechanism. Further, we compute the computational cost of security provisioning and enhancing system resilience.

Cloud Computing is emerging as a new paradigm that aims delivering computing as a utility. For the cloud computing paradigm to be fully adopted and effectively used, it is critical that the security mechanisms are robust and resilient to faults and attacks. Securing cloud systems is extremely complex due to the many interdependent tasks such as application layer firewalls, alert monitoring and analysis, source code analysis, and user identity management. It is strongly believed that we cannot build cloud services that are immune to attacks. Resiliency to attacks is becoming an important approach to address cyber-attacks and mitigate their impacts. Resiliency for mission critical systems is demanded higher. In this paper, we present a methodology to develop an Autonomic Resilient Cloud Management (ARCM) based on moving target defense, cloud service Behavior Obfuscation (BO), and autonomic computing. By continuously and randomly changing the cloud execution environments and platform types, it will be difficult especially for insider attackers to figure out the current execution environment and their existing vulnerabilities, thus allowing the system to evade attacks. We show how to apply the ARCM to one class of applications, Map/Reduce, and evaluate its performance and overhead.
 

We introduce a cloud-enabled defense mechanism for Internet services against network and computational Distributed Denial-of-Service (DDoS) attacks. Our approach performs selective server replication and intelligent client re-assignment, turning victim servers into moving targets for attack isolation. We introduce a novel system architecture that leverages a "shuffling" mechanism to compute the optimal re-assignment strategy for clients on attacked servers, effectively separating benign clients from even sophisticated adversaries that persistently follow the moving targets. We introduce a family of algorithms to optimize the runtime client-to-server re-assignment plans and minimize the number of shuffles to achieve attack mitigation. The proposed shuffling-based moving target mechanism enables effective attack containment using fewer resources than attack dilution strategies using pure server expansion. Our simulations and proof-of-concept prototype using Amazon EC2 [1] demonstrate that we can successfully mitigate large-scale DDoS attacks in a small number of shuffles, each of which incurs a few seconds of user-perceived latency.
 

Cyber-attacks continue to pose a major threat to existing critical infrastructure. Although suggestions for defensive strategies abound, Moving Target Defense (MTD) has only recently gained attention as a possible solution for mitigating cyber-attacks. The current work proposes a MTD technique that provides enhanced security through a rotation of multiple operating systems. The MTD solution developed in this research utilizes existing technology to provide a feasible dynamic defense solution that can be deployed easily in a real networking environment. In addition, the system we developed was tested extensively for effectiveness using CORE Impact Pro (CORE), Nmap, and manual penetration tests. The test results showed that platform diversity and rotation offer improved security. In addition, the likelihood of a successful attack decreased proportionally with time between rotations.
 

Moving Target Defense (MTD) changes the attack surface of a system that confuses intruders to thwart attacks. Various MTD techniques are developed to enhance the security of a networked system, but the effectiveness of these techniques is not well assessed. Security models (e.g., Attack Graphs (AGs)) provide formal methods of assessing security, but modeling the MTD techniques in security models has not been studied. In this paper, we incorporate the MTD techniques in security modeling and analysis using a scalable security model, namely Hierarchical Attack Representation Models (HARMs), to assess the effectiveness of the MTD techniques. In addition, we use importance measures (IMs) for scalable security analysis and deploying the MTD techniques in an effective manner. The performance comparison between the HARM and the AG is given. Also, we compare the performance of using the IMs and the exhaustive search method in simulations.

Software-Defined Networking (SDN) allows network capabilities and services to be managed through a central control point. Moving Target Defense (MTD) on the other hand, introduces a constantly adapting environment in order to delay or prevent attacks on a system. MTD is a use case where SDN can be leveraged in order to provide attack surface obfuscation. In this paper, we investigate how SDN can be used in some network-based MTD techniques. We first describe the advantages and disadvantages of these techniques, the potential countermeasures attackers could take to circumvent them, and the overhead of implementing MTD using SDN. Subsequently, we study the performance of the SDN-based MTD methods using Cisco's One Platform Kit and we show that they significantly increase the attacker's overheads.

Moving target defense is an area of network security research in which machines are moved logically around a network in order to avoid detection. This is done by leveraging the immense size of the IPv6 address space and the statistical improbability of two machines selecting the same IPv6 address. This defensive technique forces a malicious actor to focus on the reconnaissance phase of their attack rather than focusing only on finding holes in a machine's static defenses. We have a current implementation of an IPv6 moving target defense entitled MT6D, which works well although is limited to functioning in a peer to peer scenario. As we push our research forward into client server networks, we must discover what the limits are in reference to the client server ratio. In our current implementation of a simple UDP echo server that binds large numbers of IPv6 addresses to the ethernet interface, we discover limits in both the number of addresses that we can successfully bind to an interface and the speed at which UDP requests can be successfully handled across a large number of bound interfaces.
 

Address shuffling is a type of moving target defense that prevents an attacker from reliably contacting a system by periodically remapping network addresses. Although limited testing has demonstrated it to be effective, little research has been conducted to examine the theoretical limits of address shuffling. As a result, it is difficult to understand how effective shuffling is and under what circumstances it is a viable moving target defense. This paper introduces probabilistic models that can provide insight into the performance of address shuffling. These models quantify the probability of attacker success in terms of network size, quantity of addresses scanned, quantity of vulnerable systems, and the frequency of shuffling. Theoretical analysis shows that shuffling is an acceptable defense if there is a small population of vulnerable systems within a large network address space, however shuffling has a cost for legitimate users. These results will also be shown empirically using simulation and actual traffic traces.
 

Port hopping is a typical moving target defense, which constantly changes service port number to thwart reconnaissance attack. It is effective in hiding service identities and confusing potential attackers, but it is still unknown how effective port hopping is and under what circumstances it is a viable proactive defense because the existed works are limited and they usually discuss only a few parameters and give some empirical studies. This paper introduces urn model and quantifies the likelihood of attacker success in terms of the port pool size, number of probes, number of vulnerable services, and hopping frequency. Theoretical analysis shows that port hopping is an effective and promising proactive defense technology in thwarting network attacks.
 

Machine learning (ML) plays a central role in the solution of many security problems, for example enabling malicious and innocent activities to be rapidly and accurately distinguished and appropriate actions to be taken. Unfortunately, a standard assumption in ML - that the training and test data are identically distributed - is typically violated in security applications, leading to degraded algorithm performance and reduced security. Previous research has attempted to address this challenge by developing ML algorithms which are either robust to differences between training and test data or are able to predict and account for these differences. This paper adopts a different approach, developing a class of moving target (MT) defenses that are difficult for adversaries to reverse-engineer, which in turn decreases the adversaries' ability to generate training/test data differences that benefit them. We leverage the coevolutionary relationship between attackers and defenders to derive a simple, flexible MT defense strategy which is optimal or nearly optimal for a broad range of security problems. Case studies involving two distinct cyber defense applications demonstrate that the proposed MT algorithm outperforms standard static methods, offering effective defense against intelligent, adaptive adversaries.

Moving Target Defense (MTD) can enhance the resilience of cyber systems against attacks. Although there have been many MTD techniques, there is no systematic understanding and quantitative characterization of the power of MTD. In this paper, we propose to use a cyber epidemic dynamics approach to characterize the power of MTD. We define and investigate two complementary measures that are applicable when the defender aims to deploy MTD to achieve a certain security goal. One measure emphasizes the maximum portion of time during which the system can afford to stay in an undesired configuration (or posture), without considering the cost of deploying MTD. The other measure emphasizes the minimum cost of deploying MTD, while accommodating that the system has to stay in an undesired configuration (or posture) for a given portion of time. Our analytic studies lead to algorithms for optimally deploying MTD.