Localized Attack Research Articles

Isotropic Corrosion Performance of the Newly Developed L-PBF-A205 Aluminum Alloy

Herein, a newly developed laser-powder-bed-fusion (L-PBF) fabricated Al-Cu-Mg-Ag-Ti-B alloy, known as A205 alloy, is introduced with exceptionally refined, uniform, and texture-free microstructure comprised of an ultrafine-grained Al-matrix reinforced with eutectic-Al2Cu precipitates and TiB2 particles/agglomerates. Preliminary electrochemical characterization of the fabricated samples on planes parallel and perpendicular to the part’s building direction revealed a similar polarization response characterized by a clear passive window for both samples. The corrosion morphology assessment of both samples showed the susceptibility of Al-matrix adjacent to TiB2 agglomerates to localized corrosion attack. The electrochemical impedance spectroscopy (EIS) results also confirmed similar integrity and protectiveness for the passive layer on both samples, further affirming the obtained isotropic corrosion response of the L-PBF-A205 alloy.

LOCALISED CORROSION OF STAINLESS STEELS 316L AND 2205 IN SYNTHETIC BENTONITE PORE WATER AND BENTONITE SLURRY

One concept for Czech canister construction for deep geological repository considers stainless steel as an inner case material. Corrosion resistance to localised (pitting/crevice) corrosion and stress corrosion cracking of austenitic stainless steel 316L and duplex steel 2205 was studied. The environment was synthetic bentonite pore water (SBPOW) of domestic bentonite BaM, or a slurry of bentonite in SBPOW. Tests were carried out between 40 °C and 90 °C under anaerobic conditions of a nitrogen atmosphere. The following methods were used for evaluation: potentiostatic tests at oxidation-reduction potential of the environment, long-term exposure tests in SBPOW and slurry, slow strain rate tensile test (SSRT), exposure test of U-bends, and optical microscopy. Results showed no susceptibility of either material to stress corrosion cracking. No localised corrosion was observed up to 70 °C. There was no localised attack observed in SBPOW at 90 °C, but there was localised corrosion detected in the bentonite slurry. Forced breakdown of the passive layer during SSRT, and artificial crevices (O-rings), showed no effect on localised corrosion propagation. The detrimental effect was probably a result of the adsorption ability of the bentonite particles, which allowed breakdown of passive layer and disabled repassivation of metastable pits.

Effects of Secondary-Phase Formation on the Electrochemical Performance of a Wire Arc Additive Manufactured 420 Martensitic Stainless Steel under Different Heat Treatment Conditions.

This study aims to investigate the effects of annealing, quenching, and tempering (Q&T) heat treatments on the microstructure, crystallographic orientation, and electrochemical performance of a wall shaped 420 martensitic stainless steel part fabricated by wire arc additive manufacturing technology. The formation of a martensitic matrix with delta ferrite in the as-printed sample, islands of spherical chromium carbides embedded in a ferritic matrix in annealed sample, and intergranular chromium-rich carbides along the primary austenite grain boundaries in addition to intra-lath Fe-rich carbides in the quenching and tempering heat treated sample were detected. To characterize the corrosion performance of the fabricated samples, open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy tests were performed on all samples in aerated 3.5 wt.% NaCl electrolyte at room temperature. The corrosion morphology of the as-printed sample was characterized by localized corrosion attacks adjacent to the delta ferrite phase, while severe pitting occurred in the annealed sample due to the high susceptibility of ferritic matrix-carbide interface to pitting. In contrast to the as-printed and annealed sample, the electrochemical performance of the quenched and subsequently tempered samples was found to be significantly improved, ascribed to elimination of the chromium depleted regions adjacent to the delta ferrite phase, and enhanced protectiveness of the passive film on the alloy’s surface.

A comprehensive study on the inhibition behaviour of four carboxylate-based corrosion inhibitors focusing on efficiency drop after the optimum concentration for carbon steel in the simulated concrete pore solution

In this research, the inhibition action of four carboxylate derivatives with different numbers of functional carboxylate groups on carbon steel in 0.5 M NaCl simulating concrete pore solution was investigated using electrochemical measurements in conjunction with the XPS technique. Quantum chemical calculations were also applied to discuss the EIS data and the inhibitor's adsorption behaviour. This paper focuses on the inhibitive action of carboxylate derivates after optimal concentration. The results show that after a critical concentration, the corrosion inhibition efficiency drops to lower values, which the reasons for this matter are still uncertain. We suggest that the adsorption process is directly affected by the number of attractive and repulsive intermolecular interactions. At higher concentrations, electrostatic forces cause the local molecular clusters on the surface, which results in an imperfect layer of molecules that is vulnerable to aggressive agents such as chloride ions. Although with increasing the number of carboxylate groups, the corrosion inhibition efficiency decreases by 35%. However, quantitative XPS results reveal no noticeable reduction in the oxide layer thickness, which indicates that localized attacks lead the corrosion.

A detailed electrochemical analysis of sensitized AISI 410 martensitic stainless steel

In the present work, the effect of sensitization heat treatment on the intergranular corrosion (IGC) behavior of AISI 410 martensitic stainless steel was investigated using potentiodynamic electrochemical impedance spectroscopy (PDEIS) in conjunction with conventional methods including acid etching test, anodic potentiodynamic polarization, double-loop electrochemical potentiodynamic reactivation (DLEPR) and electrochemical noise (EN). Microstructural studies by scanning electron microscopy revealed that increasing tempering time up to 2h would be followed by more severe localized attack, but desensitization state attributed to specimens undergone prolonged tempering cannot be interpreted based on the standard test method. Susceptibility to IGC via DLEPR experiments indicates differences in the degree of sensitization (DOS) of specimens with varying tempering time, revealing a healing effect arising from prolonged tempering. The EN results elucidated the alloy tendency for active dissolution, but no obvious correlation can be established between the EN results and IGC behavior. The PDEIS data clarified that the charge transfer resistance values related to the AC responses in the middle of transpassive potential region can be utilized to investigate and compare the IGC susceptibility of the alloy. Moreover, the surface morphology of corroded samples under such experimental conditions can be used to qualitatively compare the severity of intergranular attack.

Secure Localization Algorithms Against Localization Attacks in Wireless Sensor Networks

The accuracy of the location estimation of sensors in wireless sensor networks (WSNs) is important to many applications such as environment surveillance applications. In large-scale and distributed WSNs, locations of the sensors may not be recorded during the deployment process, resulting in the need of localization techniques to help collect the sensor location information. WSNs are highly vulnerable to localization attacks since the localization techniques totally rely on the neighboring relations to determine the location of sensors. In other words, some of malicious sensor nodes can take the advantage of the neighboring relations to manipulate the localization process. In this paper, we propose two localization algorithms to overcome both common types of localization attacks, independent attacks and collusion attacks. In the first algorithm, we propose the Improved Randomized Consistency Position Algorithm to determine the location of unknown nodes using the location estimation information provided by the three random anchor nodes and using the PSO algorithm paradigm to identify the coordinates of the unknown nodes’ location. In addition, the second algorithm, which is a combination of voting method, location optimization, and the PSO algorithm paradigm to identify the location of unknown nodes, is referred to as the Enhanced Attack-Resistant Secure Localization Algorithm. Through rigorous theoretical analysis and experimentation, we demonstrate that our proposed localization algorithms yield better performance comparing to the existing methods.

A deep learning based secured energy management framework within a smart island

This study proposes a novel secured management method for renewable microgrids considering the policies required for diagnosing cyber-attacks happening in the communication networks, usually applied in the secondary control layer of microgrids (MGs). Due to the so long stochastic and bad information entering the systems in order to make malicious attacks, their location and time data links have the ability of straying of those acting in normal conditions that attempt to have an effect on the precise voltage regulation and current dividing via influencing sensors of current and voltage. The ability to extract high-level features due to the usage of fast fourier transform (FFT) and deep learning (DL) for attack detection in cyberspace has made them to be considered as a strong technique in the face of small mutations or new attacks. These self-educated and compaction abilities of DL architectures have been considered as basic techniques for hidden scheme detection from the training datum for this reason attacks have been distinguished from benign traffic. A novel method, deep learning and FFT, for cyber-security has been used in the following paper with the aim of enabling the attacks detection in DC smart MG. The deep model and traditional machine learning way are evaluated in terms of performance, and distributed attack detection has been compared to the centralized diagnosing procedure. The tests proved that the distributed attack detection system studied can be more advanced in comparison with centralized detection systems applying FFT in the role of the input index of the DL model. This suggested distributed method enables for scalable monitoring of a MG and has the ability of detecting the existence of cyber-attacks in the communications between distributed generation agents (DGAs) controlled via a control on the basis of consensus and isolating the communication link over that the attack has been injected. Any local attack detection needs restricted information about its neighbor’s dynamics. The most important factor of the proposed detection plan can be that has the ability of detecting cyber-attacks with great precision and distinguishing cyber-attack from load changes.in addition, this has been shown that the suggested model can be further useful in the detection of the attack.

Systemic mitochondrial disruption is a key event in the toxicity of bacterial pore-forming toxins to Caenorhabditis elegans.

Pore-forming toxins (PFTs) are important weapons of multiple bacterial pathogens to establish their infections. PFTs generally form pores in the plasma membrane of target cells; however, the intracellular pathogenic processes triggered after pore-formation remain poorly understood. Using Caenorhabditis elegans as a model and Bacillus thuringiensis nematicidal Cry PFTs, we show here that the localized PFT attack causes a systemic mitochondrial damage, important for the PFT toxicity. We find that PFTs punch pores only in gut cells of nematodes, but unexpectedly mitochondrial disruption is able to occur in distal unperforated regions, such as the head and muscle tissues. We demonstrate that PFTs affect the activity of the mitochondrial respiratory chain (MRC) complex I resulting in the loss of mitochondrial membrane potential (ΔΨm ), which causes further mitochondrial fragmentation and the reduction of total mitochondrial content. Worms with decreased ΔΨm or inhibited MRC activity show higher sensitivity to PFTs. The inhibition of mitochondrial fission or the increase of mitochondrial content markedly improves the survival of animals treated with PFTs. These findings suggest that mitochondrial changes underpin PFT-mediated toxicity against nematodes and that systemic mitochondrial disruption caused by localized pore-formation represents a conserved key intracellular event in the mode of action of PFTs.

Hybrid random forest and synthetic minority over sampling technique for detecting internet of things attacks

In recent decades, the internet of things (IoT) is a growing technology in smart applications, where it is highly susceptible to security breaches, due to the resource constrained nature of IoT. Among the available security breaches in IoT, Mirai, denial of service, user to root attack, remote to local attack, and probe attack renounce the networks in several ways such as saturating link bandwidth, consumption of server resources, etc. Hence, the installation of antivirus software cannot be guaranteed, because the IoT devices are equipped only with light weighted operating systems. So, intrusion detection systems are developed for the detection of IoT attacks. In this research, a new model is proposed based on random forest and synthetic minority over-sampling technique (RF-SMOTE) to detect the attacks in an IoT network. In this research, the experimental analysis is performed for IoT attack detection, where the evaluation is done on NSL-KDD dataset and network-based detection of IoT (N-BaIoT) dataset, which are the well-known datasets for IoT attack detection. In the experimental phase, the proposed RF-SMOTE model showed minimum of 0.14% and maximum of 14.25% improvement in accuracy on NSL-KDD dataset for binary class. In addition, the proposed model averagely showed minimum of 0.04% and maximum of 7.35% improvement in accuracy on NSL-KDD dataset for four classes. Additionally, the proposed RF-SMOTE model showed minimum of 0.01% and maximum of 0.04% improvement in accuracy on N-BaIoT dataset related to the existing model’s decision tree, shallow model, etc.

Isotropic corrosion performance of the newly developed L-PBF-A205 aluminum alloy

Herein, a newly developed laser-powder-bed-fusion (L-PBF) fabricated Al-Cu-Mg-Ag-Ti-B alloy, known as A205 alloy, is introduced with exceptionally refined, uniform, and texture-free microstructure comprised of an ultrafine-grained Al-matrix reinforced with eutectic-Al2Cu precipitates and TiB2 particles/agglomerates. Preliminary electrochemical characterization of the fabricated samples on planes parallel and perpendicular to the part’s building direction revealed a similar polarization response characterized by a clear passive window for both samples. The corrosion morphology assessment of both samples showed the susceptibility of Al-matrix adjacent to TiB2 agglomerates to localized corrosion attack. The electrochemical impedance spectroscopy (EIS) results also confirmed similar integrity and protectiveness for the passive layer on both samples, further affirming the obtained isotropic corrosion response of the L-PBF-A205 alloy.

Comparison of Corrosion Behavior of the Austenitic Stainless Steel 316 L in Static and Flowing Liquid Lead

Abstract Development of liquid lead cooled nuclear systems requires consideration of compatibility issues with the construction materials. In order to understand the corrosion or passivation behavior of the 316 L austenitic stainless steel, the steel specimens were exposed for 1000 h in liquid lead with 1 × 10−7 wt % oxygen level at 480 °C in static and flowing (velocity 1.6 m/s) conditions. Post-test microscopy investigation using scanning electron microscope with focused ion beam (FIB) was performed and it demonstrated significant differences in the formation of thin oxide layers in the two conditions. Maximum oxide thickness was 2 μm in the static lead (Pb) and less than 0.1 μm in the flowing Pb. In the static condition, oxide scale was not continuous and local corrosion attack was indicated; but in flowing condition the oxide layer was continuous without any corrosion attacks.

Global disassortative rewiring strategy for enhancing the robustness of scale-free networks against localized attack.

The robustness of complex networks against attack has been an important issue for decades. Most of the previous studies focused on targeted attack (TA) and random attack (RA), while recently localized attack (LA) has drawn the attention of researchers. However, the existing studies related to LA mainly aim to reveal the properties on various network topologies so that the strategy to enhance network robustness against LA is still not well studied. In this paper, we propose a global disassortative rewiring strategy to enhance the robustness of scale-free networks against LA without changing the degree distribution. The validations are conducted on simulated scale-free networks and two real-life networks. As global disassortative rewiring strategy outperforms the other strategies, it can be proved effective in enhancing network robustness against LA and may contribute to future network risk reduction. In addition, by avoiding calculating and comparing the localized-robustness measurement within each rewire operation, our strategy offers a significant advantage in computational efficiency.

Friction stir extrusion of ultra-thin wall biodegradable magnesium alloy tubes — Microstructure and corrosion response

Magnesium alloys are increasingly being considered for structural systems across different industrial sectors, including precision components of biomedical devices owing to their high specific strength and stiffness, biodegradability. For example, tubular devices such as coronary stents manufacture require defect-free, high-quality tubes with thin walls (100 μm – 1 mm) as a precursor. Here, we have produced fully consolidated, structurally sound ultra-thin walled (∼ 400 μm) AZ31 Mg alloy tubes by friction stir back extrusion (FSE) — a relatively new severe deformation process used typically to manufacture thick metallic tubes and rods. The tube cross-sectional microstructure was layered and consisted of a severely deformed stir zone with refined grains near the inner edge, a back-extruded zone with small grains near the outer edge, and a thermomechanically affected zone (TMAZ) with coarse grains develop within the central region. On the other hand, the inner tube surface microstructure had an average grain size of 4.1 ± 1.9 μm and a strong basal texture. In comparison, the outer tube surface microstructure was coarse, with an average grain size of 13.3 ± 6.4 μm with no preferred orientation. The microhardness variation along the tube wall thickness indicated the operation of multiple deformation paths during FSE. Upon exposure to Hank’s balanced salt solution at 37 °C, microgalvanic coupling resulting from the gradient through-the-thickness grain size and texture differences between the tube inner and outer surfaces, and residual strain arising from the FSE process, promoted a localized attack that preferentially initiated on the outer tube surface and progressed inwards. Static recovery induced by a short duration heat treatment at low temperature did not alter the microstructure but promoted a more general corrosion attack with a significantly reduced corrosion rate. Our results establish that FSE is a viable single-step process to manufacture ultra-thin Mg alloy tubes suitable for degradable precision tubular applications.

On the Local Leakage Resilience of Linear Secret Sharing Schemes

We consider the following basic question: to what extent are standard secret sharing schemes and protocols for secure multiparty computation that build on them resilient to leakage? We focus on a simple local leakage model, where the adversary can apply an arbitrary function of a bounded output length to the secret state of each party, but cannot otherwise learn joint information about the states. We show that additive secret sharing schemes and high-threshold instances of Shamir’s secret sharing scheme are secure under local leakage attacks when the underlying field is of a large prime order and the number of parties is sufficiently large. This should be contrasted with the fact that any linear secret sharing scheme over a small characteristic field is clearly insecure under local leakage attacks, regardless of the number of parties. Our results are obtained via tools from Fourier analysis and additive combinatorics. We present two types of applications of the above results and techniques. As a positive application, we show that the “GMW protocol” for honest-but-curious parties, when implemented using shared products of random field elements (so-called “Beaver Triples”), is resilient in the local leakage model for sufficiently many parties and over certain fields. This holds even when the adversary has full access to a constant fraction of the views. As a negative application, we rule out multiparty variants of the share conversion scheme used in the 2-party homomorphic secret sharing scheme of Boyle et al. (in: Crypto, 2016).

NUCLEAR SECURITY IN THE BRAZILIAN REALITY

This paper presents a study on the implementation of nuclear security’s knowledge in the brazilian reality, sharing the promotion of nuclear security education, aligned to guidelines and orientations of the IAEA, and covering fields such as The Regulatory Area and The Non- Regulatory Area. The study takes into account the acts of terrorism that indicate the use or threat of use of radioactive material, radiological weapons or even nuclear weapons, including local attacks where such materials are present. The Nuclear Security planning in a country includes everything. From planning a safety project from a core of a nuclear reactor to planning a gym's safety. It also includes physical security plan, safeguards plan, information security, the society's alert about any risk and actions to prevent and detect the different types of threats, such as the risk of sabotage, illegal transfer of radioactive material, among others.

Timing attacks and local timing attacks against Barrett\u2019s modular multiplication algorithm

Montgomery’s and Barrett’s modular multiplication algorithms are widely used in modular exponentiation algorithms, e.g. to compute RSA or ECC operations. While Montgomery’s multiplication algorithm has been studied extensively in the literature and many side-channel attacks have been detected, to our best knowledge no thorough analysis exists for Barrett’s multiplication algorithm. This article closes this gap. For both Montgomery’s and Barrett’s multiplication algorithm, differences of the execution times are caused by conditional integer subtractions, so-called extra reductions. Barrett’s multiplication algorithm allows even two extra reductions, and this feature increases the mathematical difficulties significantly. We formulate and analyse a two-dimensional Markov process, from which we deduce relevant stochastic properties of Barrett’s multiplication algorithm within modular exponentiation algorithms. This allows to transfer the timing attacks and local timing attacks (where a second side-channel attack exhibits the execution times of the particular modular squarings and multiplications) on Montgomery’s multiplication algorithm to attacks on Barrett’s algorithm. However, there are also differences. Barrett’s multiplication algorithm requires additional attack substeps, and the attack efficiency is much more sensitive to variations of the parameters. We treat timing attacks on RSA with CRT, on RSA without CRT, and on Diffie–Hellman, as well as local timing attacks against these algorithms in the presence of basis blinding. Experiments confirm our theoretical results.

Localization Attack by Precoder Feedback Overhearing in 5G Networks and Countermeasures

In fifth-generation (5G) cellular networks, users feed back to the base station the index of the precoder (from a codebook) to be used for downlink transmission. The precoder is strongly related to the user channel and in turn to the user position within the cell. We propose a method by which an external attacker determines the user position by passively overhearing this unencrypted layer-2 feedback signal. The attacker first builds a map of fed back precoder indices in the cell. Then, by overhearing the precoder index fed back by the victim user, the attacker finds its position on the map. We focus on the type-I single-panel codebook, which today is the only mandatory solution in the 3GPP standard. We analyze the attack and assess the obtained localization accuracy against various parameters. We analyze the localization error of a simplified precoder feedback model and describe its asymptotic localization precision. We also propose a mitigation against our attack, wherein the user randomly selects the precoder among those providing the highest rate. Simulations confirm that the attack can achieve a high localization accuracy, which is significantly reduced when the mitigation solution is adopted, at the cost of a negligible rate degradation.

A Spatial Source Location Privacy-aware Duty Cycle for Internet of Things Sensor Networks

Source Location Privacy (SLP) is an important property for monitoring assets in privacy-critical sensor network and Internet of Things applications. Many SLP-aware routing techniques exist, with most striking a tradeoff between SLP and other key metrics such as energy (due to battery power). Typically, the number of messages sent has been used as a proxy for the energy consumed. Existing work (for SLP against a local attacker) does not consider the impact of sleeping via duty cycling to reduce the energy cost of an SLP-aware routing protocol. Therefore, two main challenges exist: (i) how to achieve a low duty cycle without loss of control messages that configure the SLP protocol and (ii) how to achieve high SLP without requiring a long time spent awake. In this article, we present a novel formalisation of a duty cycling protocol as a transformation process. Using derived transformation rules, we present the first duty cycling protocol for an SLP-aware routing protocol for a local eavesdropping attacker . Simulation results on grids demonstrate a duty cycle of 10%, while only increasing the capture ratio of the source by 3 percentage points, and testbed experiments on FlockLab demonstrate an 80% reduction in the average current draw.

Recovery patterns and physics of the network.

In a progressively interconnected world, the loss of system resilience has consequences for human health, the economy, and the environment. Research has exploited the science of networks to explain the resilience of complex systems against random attacks, malicious attacks, and the localized attacks induced by natural disasters or mass attacks. Little is known about the elucidation of system recovery by the network topology. This study adds to the knowledge of network resilience by examining the nexus of recoverability and network topology. We establish a new paradigm for identifying the recovery behavior of networks and introduce the recoverability measure. Results indicate that the recovery response behavior and the recoverability measure are the function of both size and topology of networks. In small sized networks, the return to recovery exhibits homogeneous recovery behavior over topology, while the return shape is dispersed with an increase in the size of network. A network becomes more recoverable as connectivity measures of the network increase, and less recoverable as accessibility measures of network increase. Overall, the results not only offer guidance on designing recoverable networks, but also depict the recovery nature of networks deliberately following a disruption. Our recovery behavior and recoverability measure has been tested on 16 distinct network topologies. The relevant recovery behavior can be generalized based on our definition for any network topology recovering deliberately.

Credible Interdiction for Transmission Systems

This paper presents novel formulations and algorithms for $N$-$k$ interdiction problem in transmission networks. In particular, it formulates spatial and topological resource constraints on attackers for $N$-$k$ interdiction problems and illustrates the formulation with two new classes of $N$-$k$ attacks: (i) Spatial $N$-$k$ attacks where the attack is constrained by geographic distance of a bus chosen by an attacker and (ii) Topological $N$-$k$ attacks where the attack is constrained to connected components. These two specific types of $N$-$k$ attacks compute interdiction plans designed to better model localized attacks, such as those induced by natural disasters or physical attacks. We then formulate these two resource-constrained interdiction problems as bilevel, max-min optimization problems and present a novel constraint generation algorithm to solve these formulations. Detailed case studies analyzing the behavior of spatially and topologically resource-constrained problems and comparing them to the traditional $N$-$k$ interdiction problem are also presented.