In this work, we present a runtime approach, called MeltdownDetector, for detecting, isolating, and preventing ongoing Meltdown attacks that operate by causing segmentation faults. Meltdown exploits ...a hardware vulnerability that allows a malicious process to access memory locations, which do not belong to the process, including the physical and kernel memory. The proposed approach is based on a simple observation that in order for a Meltdown attack to be worthwhile, either a single byte of data located at a particular memory address or a sequence of consecutive memory addresses (i.e., sequence of bytes) need to be read, so that a meaningful piece of information can be extracted from the data leaked. MeltdownDetector, therefore, monitors segmentation faults occurring at memory addresses that are close to each other and issues a warning at runtime when these faults become “suspicious.” Furthermore, MeltdownDetector flushes the cache hierarchy after every suspicious segmentation fault, which, in turn, prevents any information leakage. In the experiments, MeltdownDetector successfully detected all the attacks and correctly pinpointed all the malicious processes involved in these attacks and did so without issuing any false alarms and without leaking even a single byte of data. Furthermore, the runtime overhead of the fastest MeltdownDetector implementation was about 1%, on average.
•A low-overhead, runtime approach for detecting, isolating, and preventing Meltdown attacks.•Monitors segmentation faults occurring at memory addresses that are close to each other.•Issues warnings at runtime when the segmentation faults become “suspicious.”•Flushes the cache hierarchy after every suspicious segmentation fault.•Evaluated with attacks spread across time and carried out with multiple malicious processes.
Modern cryptographic circuits are increasingly demanding security requirements. Since its invention, power analysis attacks are a threat to the security of such circuits. In order to contribute to ...the design of secure circuits, designers may employ countermeasures in different abstraction levels. This work presents a brief survey of countermeasures to help designers to find good solutions for the design of secure cryptographic systems. A summary is highlighted to compare the pros and cons of the approaches to help designers choose a better solution, or even provide subsidies so that new solutions can be proposed.
A traffic safety issue of two-wheeled delivery scooters is emerging because of the rapid increase in demand for food delivery services. In particular, the strict restriction of delivery time leads to ...aggressive and dangerous riding behavior that causes a high risk of crash occurrence. Systematic traffic safety management is required to effectively prevent crashes of delivery scooters. The objective of this study is to develop a monitoring framework for riding safety that informs when, where, and how serious safety problems occur. High-resolution riding behavior data obtained by an inertial measurement unit sensor installed on delivery scooters, as part of the Korean 100 naturalistic riding study (K-100NRS), were used for developing the methodology. The proposed monitoring framework consists of two components: an unsafe riding event detection algorithm and a method to identify the spatial and temporal identification of riding risks. The ratio of frequency of unsafe events to total riding time for each rider is defined as a monitoring index, which is referred to as the riding risk index in this study. Approximately 95% detection accuracy was achievable by the developed detection algorithm. In addition, the level of riding safety for each rider was evaluated based on the proposed methodology. As an application, a visualization of detected unsafe events was presented for the purpose of riding safety monitoring.
In this article we consider the problem of defending against increasing data exfiltration threats in the domain of cybersecurity. We review existing work on exfiltration threats and corresponding ...countermeasures. We consider current problems and challenges that need to be addressed to provide a qualitatively better level of protection against data exfiltration. After considering the magnitude of the data exfiltration threat, we outline the objectives of this article and the scope of the review. We then provide an extensive discussion of present methods of defending against data exfiltration. We note that current methodologies for defending against data exfiltration do not connect well with domain experts, both as sources of knowledge and as partners in decision-making. However, human interventions continue to be required in cybersecurity. Thus, cybersecurity applications are necessarily socio-technical systems that cannot be safely and efficiently operated without considering relevant human factor issues. We conclude with a call for approaches that can more effectively integrate human expertise into defense against data exfiltration.
As an energy storage or power buffering device, supercapacitor (SC) has incomparable advantages in terms of charging-discharging efficiency, response speed, and durability. Generally, a simplified ...energy estimation method based on a constant or rated capacitance can be used to evaluate the state-of-energy (SoE) of SCs. However, using a constant capacitance to evaluate the SoE of SC is very imprecise. Indeed, the SC internal parameters would change in accordance with the operating current and voltage such that the actual capacitance is far from the rated capacitance. This letter presents: a variable first-order resistance-capacitance equivalent circuit for dynamic modeling of the SC; a real-time voltage state observer used to estimate the variable internal capacitance and resistances of the SC; three different energy estimation methods; and simulated and experimental validations of the adaptive energy estimation method based on a 3000 F SC in electric vehicle applications. By using the SoE based on an experiment calibration as a reference standard, the proposed adaptive energy estimation method can improve over 0.75% of the estimated SoE error for the SC compared with the conventional estimation method.
In the last 15 years, we have witnessed a never-ending arm's race between the attacker and the defender with respect to cache-based side-channel attacks. We have seen a slew of attacks, ...countermeasures (CMs), counterattacks, counter-CMs, and so on. We analyze the evolution of this area, propose three necessary conditions for designing a successful CM, and then analyze timing and address-based CMs for popular algorithms, such as AES and PRESENT. We show that an optimal yet trivial solution for timing-based CMs is possible. Furthermore, address-based CMs are inferior to timing-based CMs, and they can be broken in <inline-formula> <tex-math notation="LaTeX">n^{O(\log (\log (n)))} </tex-math></inline-formula> time.
Microarchitectural side-channels enable an attacker to exfiltrate information via the observable side-effects of a victim's execution. Obfuscating mitigation schemes have recently gained in ...popularity for their appealing performance characteristics. These schemes, including randomized caches and DRAM traffic shapers, limit, but do not completely eliminate, side-channel leakage. An important (yet under-explored) research challenge is the quantitative study of the security effectiveness of these schemes, identifying whether these obfuscating schemes help increase the security level of a system, and if so, by how much.
In this paper, we address this research challenge by presenting Metior, a comprehensive model to quantitatively evaluate the effectiveness of obfuscating side-channel mitigations. Metior offers a way to reason about the flow of information through obfuscating schemes. Metior builds upon existing information theoretic approaches, allowing for the comprehensive side-channel leakage evaluation of active attackers, real victim applications, and state-of-the-art microarchitectural obfuscation schemes. We demonstrate the use of Metior in the concrete leakage evaluation of three microarchitectural obfuscation schemes (fully-associative random replacement caches, CEASER-S, and Camouflage), identifying unintuitive leakage behaviours across all three schemes.
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•The failure mode of metro tunnel crossing the edge of land subsidence area is revealed.•The influence of land subsidence on the structural mechanical response are studied.•The damage ...position and affected range of metro tunnel under the influence of land subsidence are discovered.•The countermeasures are discussed according to different affected positions.
Land subsidence is a prominent engineering geological problem faced by many cities in the world and poses a serious threat to urban infrastructures. Xi'an is one of the cities in China that has suffered the most serious land subsidence disasters and has thus faced the challenges in its ongoing metro construction. To solve this problem, in this paper we carried out a model test and numerical simulation of metro tunnel that crosses a land subsidence area and analyzed the mechanical response of the tunnel and the deformation and failure characteristics of the lining. The results show that the tunnel exhibits downward flexural deformation in the middle, slight warpage on both ends in the longitudinal direction, and local torsion in the horizontal direction in the presence of land subsidence, the maximum deformation of the ground surface is about 80% of the tunnel deformation. Furthermore, the vault and inverted arch are in opposite tension–compression states, and the lining stress decreases inside the subsidence area but increases outside it. When the actual subsidence reaches 225 cm, the metro tunnel crossing the edge of the land subsidence area has failed. We find that the deformation and failure of metro tunnel crossing land subsidence area is a combination mode of flexural tension–compression and local torsion, which affects 2.5 times the length of the intersection between the tunnel and the subsidence area. Also, some countermeasures and suggestions are proposed to deal with the adverse impacts of land subsidence on metro tunnels.
Abstract
The performance of military equipment keeps improving, and troops are equipped with more and more sophisticated weapons and equipment, highlighting the importance of equipment maintenance ...and support. Without strong equipment support capability, it is impossilbe to cope with the fast-paced and high-intensity modern warfare, and to effectively give play to the role and advantages of equipment systems integration. Therefore, it is of great significance to have a profound study of and improve the equipment support capability assessment method. Based on requirement analysis, we built an equipment support capability assessment indicator system of the Army Digital Medium-sized Synthetic Brigade in cross-domain operations. The weight of the assessment indicator system was determined using the AHP analytic hierarchy process. The equipment support capability assessment model was constructed. With the data obtained from the exercises using real equipment and system-of-systems (SoS) countermeasure simulation tests, we completed the assessment of the equipment support capability of the Synthetic Brigade using neural network algorithms.
The increasing risks of radiological or nuclear attacks or associated accidents have served to renew interest in developing radiation medical countermeasures. The development of prospective ...countermeasures and the subsequent gain of Food and Drug Administration (FDA) approval are invariably time consuming and expensive processes, especially in terms of generating essential human data. Due to the limited resources for drug development and the need for expedited drug approval, drug developers have turned, in part, to the strategy of repurposing agents for which safety and clinical data are already available. Approval of drugs that are already in clinical use for one indication and are being repurposed for another indication is inherently faster and more cost effective than for new agents that lack regulatory approval of any sort. There are four known growth factors which have been repurposed in the recent past as radiomitigators following the FDA Animal Rule: Neupogen, Neulasta, Leukine, and Nplate. These four drugs were in clinic for several decades for other indications and were repurposed. A large number of additional agents approved by various regulatory authorities for given indications are currently under investigation for dual use for acute radiation syndrome or for delayed pathological effects of acute radiation exposure. The process of drug repurposing, however, is not without its own set of challenges and limitations.
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