Active Directory Kerberoasting Attack: Monitoring and Detection Techniques

Autoři
Rok
2020
Publikováno
Proceedings of the 6th International Conference on Information Systems Security and Privacy. Madeira: SciTePress, 2020. p. 432-439. ISSN 2184-4356. ISBN 978-989-758-399-5.
Typ
Stať ve sborníku
Anotace
The paper focus is the detection of Kerberoasting attack in Active Directory environment. The purpose of the attack is to extract service accounts’ passwords without need for any special user access rights or privilege escalation, which makes it suitable for initial phases of network compromise and further pivot for more interesting accounts. The main goal of the paper is to discuss the monitoring possibilities, setting up detection rules built on top of native Active Directory auditing capabilities, including possible ways to minimize false positive alerts.

Behavior Anomaly Detection in IoT Networks

Rok
2020
Publikováno
Proceeding of the International Conference on Computer Networks, Big Data and IoT (ICCBI - 2019). Cham: Springer International Publishing, 2020. p. 465-473. Lecture Notes on Data Engineering and Communications Technologies. vol. 49. ISSN 2367-4520. ISBN 978-3-030-43192-1.
Typ
Kapitola v knize
Anotace
Data encryption makes deep packet inspection less suitable nowadays, and the need of analyzing encrypted traffic is growing. Machine learning brings new options to recognize a type of communication despite the heterogeneity of encrypted IoT traffic right at the network edge. We propose the design of scalable architecture and the method for behavior anomaly detection in IoT networks. Combination of two existing semi-supervised techniques that we used ensures higher reliability of anomaly detection and improves results achieved by a single method. We describe conducted classification and anomaly detection experiments allowed thanks to existing and our training datasets. Presented satisfying results provide a subject for further work and allow us to elaborate on this idea.

Bi-directional Transformation between Normalized Systems Elements and Domain Ontologies in OWL

Autoři
Suchánek, M.; Pergl, R.; Uhnák, P.; Mannaert, H.
Rok
2020
Publikováno
Proceedings of the 15th International Conference on Evaluation of Novel Approaches to Software Engineering. Porto: SciTePress - Science and Technology Publications, 2020. p. 74-85. ISSN 2184-4895. ISBN 978-989-758-421-3.
Typ
Stať ve sborníku
Anotace
Knowledge representation in OWL ontologies gained a lot of popularity with the development of Big Data, Artificial Intelligence, Semantic Web, and Linked Open Data. OWL ontologies are very versatile, and there are many tools for analysis, design, documentation, and mapping. They can capture concepts and categories, their properties and relations. Normalized Systems (NS) provide a way of code generation from a model of so-called NS Elements resulting in an information system with proven evolvability. The model used in NS contains domain-specific knowledge that can be represented in an OWL ontology. This work clarifies the potential advantages of having OWL representation of the NS model, discusses the design of a bi-directional transformation between NS models and domain ontologies in OWL, and describes its implementation. It shows how the resulting ontology enables further work on the analytical level and leverages the system design. Moreover, due to the fact that NS metamodel is metacircular, the transformation can generate ontology of NS metamodel itself. It is expected that the results of this work will help with the design of larger real-world applications as well as the metamodel and that the transformation tool will be further extended with additional features which we proposed.

Bounds on the period of the continued fraction after a Möbius transformation

Autoři
Starosta, Š.; Řada, H.
Rok
2020
Publikováno
Journal of Number Theory. 2020, 212 122-172. ISSN 0022-314X.
Typ
Článek
Anotace
We study Möbius transformations (also known as linear fractional transformations) of quadratic numbers. We construct explicit upper and lower bounds on the period of the continued fraction expansion of a transformed number as a function of the period of the continued fraction expansion of the original number. We provide examples that show that the bound is sharp.

Classical Superintegrable Systems in a Magnetic Field that Separate in Cartesian Coordinates

Autoři
Marchesiello, A.; Šnobl, L.
Rok
2020
Publikováno
Symmetry, Integrability and Geometry: Methods and Applications (SIGMA). 2020, 16 ISSN 1815-0659.
Typ
Článek
Anotace
We consider superintegrability in classical mechanics in the presence of magnetic fields. We focus on three-dimensional systems which are separable in Cartesian coordinates. We construct all possible minimally and maximally superintegrable systems in this class with additional integrals quadratic in the momenta. Together with the results of our previous paper [J. Phys. A: Math. Theor. 50 (2017), 245202, 24 pages], where one of the additional integrals was by assumption linear, we conclude the classification of three-dimensional quadratically minimally and maximally superintegrable systems separable in Cartesian coordinates. We also describe two particular methods for constructing superintegrable systems with higher-order integrals.

Classification Methods for Internet Applications

Autoři
Holeňa, M.; Pulc, P.; Kopp, M.
Rok
2020
Publikováno
Cham: Springer, 2020. Studies in Big Data. vol. 69. ISSN 2197-6503. ISBN 978-3-030-36961-3.
Typ
Kniha
Anotace
This book explores internet applications in which a crucial role is played by classification, such as spam filtering, recommender systems, malware detection, intrusion detection and sentiment analysis. It explains how such classification problems can be solved using various statistical and machine learning methods, including K nearest neighbours, Bayesian classifiers, the logit method, discriminant analysis, several kinds of artificial neural networks, support vector machines, classification trees and other kinds of rule-based methods, as well as random forests and other kinds of classifier ensembles. The book covers a wide range of available classification methods and their variants, not only those that have already been used in the considered kinds of applications, but also those that have the potential to be used in them in the future. The book is a valuable resource for post-graduate students and professionals alike.

Das Contract - A Visual Domain Specific Language for Modeling Blockchain Smart Contracts

Rok
2020
Publikováno
Advances in Enterprise Engineering XIII. Cham: Springer, 2020. p. 149-166. ISBN 978-3-030-37932-2.
Typ
Stať ve sborníku
Anotace
A Blockchain (BC) is a technology that introduces a decentralized, replicated, autonomous, and secure databases. A smart contract (SC) is a transaction embedded in the blockchain that contains executable code and its internal storage, offering immutable execution and record keeping. The SC has enormous potential in automating traditional paper contracts and encoding contract logic into program code. Thus, replacing the role of a notary and a central authority. It may dramatically reduce an effort with administration workload and enforcement of such contracts. In this paper, we propose a new visual domain specific language that can capture the SC in a user-friendly way and eliminate the errors associated with programming since the SC code is automatically generated from models. Finally, an open-source proof-of-concept environment for designing and generating the SC is introduced to demonstrate the feasibility of proposed concepts.

Laying the Foundation for Design System Ontology

Rok
2020
Publikováno
Trends and Innovations in Information Systems and Technologies. Springer, Cham, 2020. p. 778-787. ISSN 2194-5357. ISBN 978-3-030-45687-0.
Typ
Stať ve sborníku
Anotace
There is a growing need for more client applications for different platforms while maintaining a consistent appearance. Managing this usually requires a lot of tedious labour work. In this paper, we explored what should be included in the design system based on the real-world needs, how to represent and formalise it using semantic web technologies to achieve evolvability and interoperability, and how to convert it into code automatically leveraging the Normalised System theory. Our solution is already a foundation for the ontology representing the design system and working prototype of the code generator using the ontology.

Lightweight Authentication and Secure Communication Suitable for IoT Devices

Rok
2020
Publikováno
Proceedings of the 6th International Conference on Information Systems Security and Privacy. Madeira: SciTePress, 2020. p. 75-83. ISSN 2184-4356. ISBN 978-989-758-399-5.
Typ
Stať ve sborníku
Anotace
In this paper we present the protocols for lightweight authentication and secure communication for IoT and embedded devices. The protocols are using a PUF/TRNG combined circuit as a basic building block. The goal is to show the possibilities of securing communication and authentication of the embedded systems, using PUF and TRNG for secure key generation, without requirement to store secrets on the device itself, thus allowing to significantly simplify the problem of key management on the simple hardware devices and microcontrollers, while allowing secure communication.

Missing Features Reconstruction Using a Wasserstein Generative Adversarial Imputation Network

Rok
2020
Publikováno
Computational Science - ICCS 2020. Cham: Springer, 2020. p. 225-239. vol. 12140. ISSN 1611-3349. ISBN 978-3-030-50423-6.
Typ
Stať ve sborníku
Anotace
Missing data is one of the most common preprocessing problems. In this paper, we experimentally research the use of generative and non-generative models for feature reconstruction. Variational Autoencoder with Arbitrary Conditioning (VAEAC) and Generative Adversarial Imputation Network (GAIN) were researched as representatives of generative models, while the denoising autoencoder (DAE) represented non-generative models. Performance of the models is compared to traditional methods k-nearest neighbors (k-NN) and Multiple Imputation by Chained Equations (MICE). Moreover, we introduce WGAIN as the Wasserstein modification of GAIN, which turns out to be the best imputation model when the degree of missingness is less than or equal to 30%. Experiments were performed on real-world and artificial datasets with continuous features where different percentages of features, varying from 10% to 50%, were missing. Evaluation of algorithms was done by measuring the accuracy of the classification model previously trained on the uncorrupted dataset. The results show that GAIN and especially WGAIN are the best imputers regardless of the conditions. In general, they outperform or are comparative to MICE, k-NN, DAE, and VAEAC.

Multi-Agent Path Finding with Mutex Propagation

Autoři
Surynek, P.; Koenig, S.; Kumar, S.; Li, J.; Zhang, H.
Rok
2020
Publikováno
Proceedings of the Thirtieth International Conference on Automated Planning and Scheduling. Menlo Park: AAAI Press, 2020. p. 323-332. ISBN 978-1-57735-824-4.
Typ
Stať ve sborníku
Anotace
Mutex propagation is a form of efficient constraint propagation popularly used in AI planning to tightly approximate the reachable states from a given state. We utilize this idea in the context of Multi-Agent Path Finding (MAPF). When adapted to MAPF, mutex propagation provides stronger constraints for conflict resolution in Conflict-Based Search (CBS), a popular optimal MAPF algorithm, and provides it with the ability to identify and reason with symmetries in MAPF.

Novel Dummy Rounds Schemes as a DPA Countermeasure in PRESENT Cipher

Autoři
Novotný, M.; Jeřábek, S.; Moucha, P.
Rok
2020
Publikováno
Proceedings of the 23rd International Symposium on Design and Diagnostics of Electronic Circuits and Systems. Piscataway, NJ: IEEE, 2020. p. 1-4. ISBN 978-1-7281-9938-2.
Typ
Stať ve sborníku
Anotace
The Dummy Rounds Side-Channel Attacks countermeasure scheme for digital design has been proposed in earlier work. Its experimental evaluation and analysis revealed weaknesses that resulted in the proposal of an enhanced Dummy Rounds scheme. In this paper, we present the implementation of the proposed enhancement of Dummy Rounds scheme in PRESENT cipher and provide its experimental evaluation using Welch’s t-test. We further propose several novel modifications of dummy Rounds scheme as a solution to other security problems we have encountered. Novel Dummy Rounds scheme, namely its modifications proposed in this paper, are superior to earlier proposed schemes in terms of side-channel leakage prevention.

O líných algoritmech, logice a hledání cest pro roboty

Autoři
Rok
2020
Publikováno
Vesmír. 2020, 2020(99), 352-354. ISSN 1214-4029.
Typ
Článek
Anotace
Jak přimět desetiletí propracovávané všemožné triky pracovat na hledání optimální cesty pro mobilní roboty k dosažení cíle a chytře odřezávat neperspektivní kandidáty na vyhnutí se srážkám.

On approximate enhanced covers under Hamming distance

Autoři
Rok
2020
Publikováno
Discrete Applied Mathematics. 2020, 274 67-80. ISSN 0166-218X.
Typ
Článek
Anotace
A border p of a string x is an enhanced cover of x if the number of positions of x that lie within some occurrence of p is the maximum among all borders of x. (String p is a border of x if p is both a proper prefix and a suffix of x.) In this paper, two more general notions based on enhanced covers are introduced: a k-approximate enhanced cover and a relaxed k-approximate enhanced cover, where a fixed maximum number of errors k under the Hamming distance is considered. The k-approximate enhanced cover of x is its border, and its k-approximate occurrences are also considered in the covered number of positions of x. The relaxed k-approximate enhanced cover of x is a factor of x and a k-approximate border of x. Algorithms that compute all the variations of k-approximate enhanced covers mentioned above are presented in this paper.

On Electromagnetic Actuator Control in The Active Suspension Systems

Autoři
Rok
2020
Publikováno
Proceedings of the VI international Congress "INNOVATIONS 2020". Sofia: Scientific-technical union of mechanical engineering, 2020. p. 98-100. vol. I. ISSN 2603-3763.
Typ
Stať ve sborníku
Anotace
In the paper, the design of a linear motor as an actuator in-vehicle active suspension systems will be presented. The attention is focused on several interesting design aspects of a non-traditional actuator (a linear synchronous permanent magnet motor with electronic commutation) controlled to obtain a variable mechanical force for a car active suspension. The main advantage of such a solution is the possibility to generate desired forces acting between the unsprung (wheel) and sprung (car body) masses of the car, providing good insulation of the car sprung mass from the road surface disturbances. In addition, under certain circumstances, it is possible to reduce or even eliminate the demands concerning the external power source.

On Hankel matrices commuting with Jacobi matrices from the Askey scheme

Autoři
Štampach, F.; Šťovíček, P.
Rok
2020
Publikováno
Linear Algebra and Its Applications. 2020, 591 235-267. ISSN 0024-3795.
Typ
Článek
Anotace
A complete characterization is provided of Hankel matrices commuting with Jacobi matrices which correspond to hypergeometric orthogonal polynomials from the Askey scheme. It follows, as the main result of the paper, that the generalized Hilbert matrix is the only prominent infinite-rank Hankel matrix which, if regarded as an operator on l2(N0), is diagonalizable by application of the commutator method with Jacobi matrices from the mentioned families.

On modification of Boyer-Moore-horspool's algorithm for tree pattern matching in linearised trees

Autoři
Rok
2020
Publikováno
Theoretical Computer Science. 2020, 830 60-90. ISSN 0304-3975.
Typ
Článek
Anotace
Tree pattern matching on ordered trees is an important problem in Computer Science. Ordered trees can be represented as strings with additional properties via various linearisations. We present a backward tree pattern matching algorithm for ordered trees for various linear representations of trees and tree patterns. The algorithm adaptations find all occurrences of a single given tree pattern which match an input tree regardless of the chosen linearisation. The algorithms preserve the properties and advantages of standard backward string pattern matching using Boyer-Moore-Horspool's bad character shift heuristics. The number of symbol comparisons in the backward tree pattern matching can be sublinear in the size of the input tree. As in the case of the string version of Boyer-Moore-Horspool's matching algorithm, the size of the bad character shift table used by the algorithm is linear in the size of the alphabet. We compare the algorithm adaptations with the algorithm using originally chosen linear representation and with the best performing previously existing algorithms based on (non-linearised) tree pattern matching using finite tree automata or stringpath matchers. We show that the presented backward tree pattern matching algorithms outperform the non-linearising ones for single pattern matching and they perform among themselves comparably. (C) 2020 Elsevier B.V. All rights reserved.

On satisfisfiability modulo theories in continuous multi-agent path finding: Compilation-based and search-based approaches compared

Autoři
Rok
2020
Publikováno
Proceedings of the 12th International Conference on Agents and Artificial Intelligence. Porto: SciTePress - Science and Technology Publications, 2020. p. 182-193. vol. 2. ISSN 2184-433X. ISBN 978-989-758-395-7.
Typ
Stať ve sborníku
Anotace
Multi-agent path finding (MAPF) in continuous space and time with geometric agents, i.e. agents of various geometric shapes moving smoothly between predefined positions, is addressed in this paper. We analyze a new solving approach based on satisfiability modulo theories (SMT) that is designed to obtain makespan optimal solutions.

On Synchronizing Tree Automata and Their Work–Optimal Parallel Run, Usable for Parallel Tree Pattern Matching

Rok
2020
Publikováno
SOFSEM 2020: Theory and Practice of Computer Science. Cham: Springer, 2020. p. 576-586. Lecture Notes in Computer Science. vol. 12011. ISSN 0302-9743. ISBN 978-3-030-38918-5.
Typ
Stať ve sborníku
Anotace
We present a way of synchronizing finite tree automata: We define a synchronizing term and a k-local deterministic finite bottom–up tree automaton. Furthermore, we present a work–optimal parallel algorithm for parallel run of the deterministic k-local tree automaton in O(log n) time with ⌈n/ log n⌉ processors, for k ≤ log n, or in O(k) time with ⌈n/ k⌉ processors, for k ≥ log n, where n is the number of nodes of an input tree, on EREW PRAM. Finally, we prove that the deterministic finite bottom–up tree automaton that is used as a standard tree pattern matcher is k-local with respect to the height of a tree pattern.

Partitioning graphs into induced subgraphs

Autoři
Rok
2020
Publikováno
Discrete Applied Mathematics. 2020, 272 31-42. ISSN 0166-218X.
Typ
Článek
Anotace
We study the Partition into H problem from the parameterized complexity point of view. In the Partition into H problem the task is to partition the vertices of a graph G into sets V_1,...,V_r such that the graph H is isomorphic to the subgraph of G induced by each set V_i for i =1,...,r. The pattern graph H is fixed. For the parameterization we consider three distinct structural parameters of the graph G - namely the tree-width, the neighborhood diversity, and the modular-width. For the parameterization by the neighborhood diversity we obtain an FPT algorithm for every graph H. For the parameterization by the tree-width we obtain an FPT algorithm for every connected graph H, thus resolving an open question of Gajarský et al. (2013). Finally, for the parameterization by the modular-width we derive an FPT algorithm for every prime graph H.

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Za obsah stránky zodpovídá: doc. Ing. Štěpán Starosta, Ph.D.