Achieving network resiliency using sound theoretical and practical methods

Computer networks have revolutionized the life of every citizen in our modern intercon- nected society. The impact of networked systems spans every aspect of our lives, from financial transactions to healthcare and critical services, making these systems an attractive target for malicious entities that aim to make financial or political profit. Specifically, the past decade has witnessed an astounding increase in the number and complexity of sophisti- cated and targeted attacks, known as advanced persistent threats (APT). Those attacks led to a paradigm shift in the security and reliability communities’ perspective on system design; researchers and government agencies accepted the inevitability of incidents and malicious attacks, and marshaled their efforts into the design of resilient systems. Rather than focusing solely on preventing failures and attacks, resilient systems are able to maintain an acceptable level of operation in the presence of such incidents, and then recover gracefully into normal operation. Alongside prevention, resilient system design focuses on incident detection as well as timely response. Unfortunately, the resiliency efforts of research and industry experts have been hindered by an apparent schism between theory and practice, which allows attackers to maintain the upper hand advantage. This lack of compatibility between the theory and practice of system design is attributed to the following challenges. First, theoreticians often make impractical and unjustifiable assumptions that allow for mathematical tractability while sacrificing accuracy. Second, the security and reliability communities often lack clear definitions of success criteria when comparing different system models and designs. Third, system designers often make implicit or unstated assumptions to favor practicality and ease of design. Finally, resilient systems are tested in private and isolated environments where validation and reproducibility of the results are not publicly accessible. In this thesis, we set about showing that the proper synergy between theoretical anal- ysis and practical design can enhance the resiliency of networked systems. We illustrate the benefits of this synergy by presenting resiliency approaches that target the inter- and intra-networking levels. At the inter-networking level, we present CPuzzle as a means to protect the transport control protocol (TCP) connection establishment channel from state- exhaustion distributed denial of service attacks (DDoS). CPuzzle leverages client puzzles to limit the rate at which misbehaving users can establish TCP connections. We modeled the problem of determining the puzzle difficulty as a Stackleberg game and solve for the equilibrium strategy that balances the users’ utilizes against CPuzzle’s resilience capabilities. Furthermore, to handle volumetric DDoS attacks, we extend CPuzzle and implement Midgard, a cooperative approach that involves end-users in the process of tolerating and neutralizing DDoS attacks. Midgard is a middlebox that resides at the edge of an Internet service provider’s network and uses client puzzles at the IP level to allocate bandwidth to its users. At the intra-networking level, we present sShield, a game-theoretic network response engine that manipulates a network’s connectivity in response to an attacker who is moving laterally to compromise a high-value asset. To implement such decision making algorithms, we leverage the recent advances in software-defined networking (SDN) to collect logs and security alerts about the network and implement response actions. However, the programma- bility offered by SDN comes with an increased chance for design-time bugs that can have drastic consequences on the reliability and security of a networked system. We therefore introduce BiFrost, an open-source tool that aims to verify safety and security proper- ties about data-plane programs. BiFrost translates data-plane programs into functionally equivalent sequential circuits, and then uses well-established hardware reduction, abstrac- tion, and verification techniques to establish correctness proofs about data-plane programs. By focusing on those four key efforts, CPuzzle, Midgard, sShield, and BiFrost, we believe that this work illustrates the benefits that the synergy between theory and practice can bring into the world of resilient system design. This thesis is an attempt to pave the way for further cooperation and coordination between theoreticians and practitioners, in the hope of designing resilient networked systems

Regulation by Software

Software is neither law nor architecture. It is its own modality of regulation. This Note builds on Larry Lessig’s famous formulation that “code is law” to argue that Lessig was wrong to equate computer software with physical architecture. Although software resembles both law and architecture in its power to constrain behavior, it has features that distinguish it from both. The Note identifies four relevant attributes of software: It is ruleish, potentially nontransparent, impossible to ignore, and vulnerable to sudden failure. By assessing the impact of these characteristics in a given context, one can decide whether software is a good or a bad choice to solve a regulatory problem. Part I situates software within Lessig’s theory of different and complementary modalities of regulation that constrain individuals. In Code, he postulates four such modalities: law, social norms, markets, and physical architecture. He then argues that software is a subspecies of physical architecture as a modality. I argue instead that three basic characteristics of software establish it as a distinct modality that should not be conflated with any of the others: First, software is automated. Once set in motion by a programmer, a computer program makes its determinations mechanically, without further human intervention. Second, software is immediate. Rather than relying on sanctions imposed after the fact to enforce its rules, it simply prevents the forbidden behavior from occurring. Third, software is plastic. Programmers can implement almost any system they can imagine and describe precisely. Software is like physical architecture and unlike law in being automated and immediate. However, plasticity is more characteristic of legal systems than of architectural ones. Software’s plasticity interacts with its automation and its immediacy to produce consequences that set it apart from both law and physical architecture. In Part II, I turn to these distinctive consequences. There are four recurring and predictable patterns present in any regulation by software: First, along the traditional continuum between rules and standards, software lies at the extreme rule-bound end. Second, software can regulate without transparency. Frequently, those regulated by software may have no reasonable way to determine the overall shape of the line between prohibited and permitted behavior. Third, software rules cannot be ignored. Parties facing a decision made by software can, at best, take steps to undo what software has wrought. Fourth, software is more fragile than other systems of regulation. Hackers can turn its plasticity against it, and its automated operation means that unintended consequences are shielded from human review. Part III applies this analysis to two case studies. It predicts that software is a good way to manage negotiations and transactions in online marketplaces such as online auction sites and electronic stock exchanges. On the other hand, it predicts several pitfalls for the use of software to restrict the distribution of digital media

A technical approach to privacy based on mobile agents protected by tamper-resistant hardware

We address the problem of protecting the privacy of individuals in the information society. Our goal is to devise technical means that allow users to actively participate in the management and use of information related to them. The advent of the information society creates serious challenges for the privacy of individuals. Due to the drastically improving communication infrastructure, ever larger amounts of ever more precise information become available. The problem with the free availability of this information is not only the risk that the information can be abused by powerful institutions, but also that this can lead to an unconfined mutual surveillance of individuals, which can have adverse effects on society as a whole. We argue that individuals should be empowered to define for themselves the level of privacy they are comfortable with. This can be achieved by notifying them whenever information on them is created, accessed, or modified and by giving them some control over the use of this information. The notification informs individuals who is using what information on them and allows to detect possible problems with this use. The control allows individuals to resolve most (or at least some) of these problems. Obviously this requires that the individuals can trust the users of information to properly implement these notifications and to offer an effective control. We analyze the concept of trust more closely and distinguish between the optimistic and the pessimistic approach to trust, which can both provide the foundation for the protection of privacy. The former is based on the classical concepts of control and sanctions, while the latter tries to prevent malicious behaviour. We choose to pursue the pessimistic approach and investigate in technical means that can be used for this purpose. A promising technology is the mobile agent paradigm, which is a new approach to structure distributed applications. Its main idea is to move both the code and the state of an object to another principal for remote execution. This indicates that the mobile agent paradigm also embraces the object-oriented programming paradigm, which allows us to encapsulate a data item and to specify an access control policy on it. Since the mobile agent is physically moved to a remote location that is under the control of a different principal, it needs to be protected from this principal who is responsible for its execution. This problem constitutes the major diffculty for using the mobile agent paradigm for privacy protection and is explored in great detail. Based on the discussion in the relevant literature, we decide on an approach that relies on a trusted and tamper-resistant hardware device, which is developed on a conceptual level. The approach is further explored in the context of the mobile agent paradigm, where it allows us to realize more elaborate protection goals that may be desirable for the owner of the mobile agent. These are developed in the form of conducts, which regroup the goal, the requirements, as well as a specification of the necessary collaboration to achieve this goal. Finally, we return to the original problem and describe how the presented technology can be used to improve the protection of privacy. This results in a rather complex framework, in which information on individuals cannot be used freely, but where this use is constrained by the level of privacy desired by the subject of the information. The major problem of this framework is the increased complexity that individuals have to deal with. This problem is addressed with an additional level of indirection that attempts to confine the complexity and to delegate it to trusted experts. We believe that this approach, despite its complexity, is a viable means to address the urgent problems of privacy protection, which do not lend themselves to simple solutions

Programming Languages and Systems

This open access book constitutes the proceedings of the 31st European Symposium on Programming, ESOP 2022, which was held during April 5-7, 2022, in Munich, Germany, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2022. The 21 regular papers presented in this volume were carefully reviewed and selected from 64 submissions. They deal with fundamental issues in the specification, design, analysis, and implementation of programming languages and systems

Blockchain-Based Distributed Network Architecture for Internet of Things

IoT networks have already been widely deployed due to their convenience and low-cost advantage. However, due to the lack of strong self-protection mechanisms and the imperfect network architectures, many IoT devices are vulnerable to malicious cyber-attacks, which will further threaten the availability and security of IoT applications. Therefore, securing the network infrastructure while protecting data from malicious or unauthorized devices/users become a vital aspect of IoT network design. In the thesis, two types of IoT security mechanisms are mainly investigated, namely, IoT routing protection and smart community device authentication. By adopting the distributed consensus mechanism, we propose a blockchain-based reputation management system in IoT routing networks to overcome the limitation of centralized router RM systems. The proposed solution utilizes the blockchain technique as a decentralized database to store routing reports for calculating reputation of each router. With the proposed reputation calculation mechanism, the reliability of each router would be evaluated, and the malicious misbehaving routers with low reputations will be blacklisted and get isolated. More importantly, we develop an efficient group mining process for blockchain technique in order to improve the efficiency of block generation and reduce the resource consumption. We propose a novel sidechain structure via optimized two-way peg protocol for device authentication in the smart community in order to overcome the limitations of existing authentication approaches. The proposed sidechain structure requires the mainchain mining nodes to only store the local mainchain blocks without downloading the entire mainchain after each block generation. By using Simplified Payment Verification (SPV) proof, the existence of the target authentication information could be proved. Moreover, we propose an optimized two-way peg protocol in order to prevent the worthless information injection attack during the information sharing procedure. Consequently, the simulation results prove the superiority of the proposed scheme in terms of reducing authentication time, improving information management efficiency and decreasing storage consumption as compared to existing works, and the applicability and feasibility of the optimized two-way peg protocol have been approved

Programming Languages and Systems

This open access book constitutes the proceedings of the 31st European Symposium on Programming, ESOP 2022, which was held during April 5-7, 2022, in Munich, Germany, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2022. The 21 regular papers presented in this volume were carefully reviewed and selected from 64 submissions. They deal with fundamental issues in the specification, design, analysis, and implementation of programming languages and systems

Tools and Algorithms for the Construction and Analysis of Systems

This open access book constitutes the proceedings of the 28th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS 2022, which was held during April 2-7, 2022, in Munich, Germany, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2022. The 46 full papers and 4 short papers presented in this volume were carefully reviewed and selected from 159 submissions. The proceedings also contain 16 tool papers of the affiliated competition SV-Comp and 1 paper consisting of the competition report. TACAS is a forum for researchers, developers, and users interested in rigorously based tools and algorithms for the construction and analysis of systems. The conference aims to bridge the gaps between different communities with this common interest and to support them in their quest to improve the utility, reliability, exibility, and efficiency of tools and algorithms for building computer-controlled systems

Secrecy for Mobile Implementations of Security Protocols

Mobile code technology offers interesting possibilities to the practitioner, but also raises strong concerns about security. One aspect of security is secrecy, the preservation of confidential information. This thesis investigates the modelling, specification and verification of secrecy in mobile applications which access and transmit confidential information through a possibly compromised medium (e.g. the Internet). These applications can be expected to communicate secret information using a security protocol, a mechanism to guarantee that the transmitted data does not reach unauthorized entities. The central idea is therefore to relate the secrecy properties of the application to those of the protocol it implements, through the definition of a ``confidential protocol implementation'' relation. The argument takes an indirect form, showing that a confidential implementation transmits secret data only in the ways indicated by the protocol. We define the implementation relation using labelled transition semantics, bisimulations and relabelling functions. To justify its technical definition, we relate this property to a notion of noninterference for nondeterministic systems derived from Cohen's definition of Selective Independency. We also provide simple and local conditions that greatly simplify its verification, and report on our experiments on an architecture showing how the proposed formulations could be used in practice to enforce secrecy of mobile code