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This thesis focuses on the development and implementation of a Datagram Transport Layer Security (DTLS) communication framework within the ns-3 network simulator, specifically targeting the LoRaWAN model network. The primary aim is to analyse the behaviour and performance of DTLS protocols across different network conditions within a LoRaWAN context. The key aspects of this work include the following.
Utilization of ns-3: This thesis leverages ns-3’s capabilities as a powerful discrete event network simulator. This platform enables the emulation of diverse network environments, characterized by varying levels of latency, packet loss, and bandwidth constraints.
Emulation of Network Challenges: The framework specifically addresses unique challenges posed by certain network configurations, such as duty cycle limitations. These constraints, which limit the time allocated for data transmission by each device, are crucial in understanding the real-world performance of DTLS protocols.
Testing in Multi-client-server Scenarios: A significant feature of this framework is its ability to test DTLS performance in complex scenarios involving multiple clients and servers. This is vital for assessing the behaviour of a protocol under realistic network conditions.
Realistic Environment Simulation: By simulating challenging network conditions, such as congestion, limited bandwidth, and resource constraints, the framework provides a realistic environment for thorough evaluation. This allows for a comprehensive analysis of DTLS in terms of security, performance, and scalability.
Overall, this thesis contributes to a deeper understanding of DTLS protocols by providing a robust tool for their evaluation under various and challenging network conditions.
Linux and Linux-based operating systems have been gaining more popularity among the general users and among developers. Many big enterprises and large companies are using Linux for servers that host their websites, some even require their developers to have knowledge about Linux OS. Even in embedded systems one can find many Linux-based OS that run them. With its increasing popularity, one can deduce the need to secure such a system that many personnel rely on, be it to protect the data that it stores or to protect the integrity of the system itself, or even to protect the availability of the services it offers. Many researchers and Linux enthusiasts have been coming up with various ways to secure Linux OS, however new vulnerabilities and new bugs are always found, by malicious attackers, with every update or change, which calls for the need of more ways to secure these systems.
This Thesis explores the possibility and feasibility of another way to secure Linux OS, specifically securing the terminal of such OS, by altering the commands of the terminal, getting in the way of attackers that have gained terminal access and delaying, giving more time for the response teams and for forensics to stop the attack, minimize the damage, restore operations, and to identify collect and store evidence of the cyber-attack. This research will discuss the advantages and disadvantages of various security measures and compare and contrast with the method suggested in this research.
This research is significant because it paints a better picture of what the state of the art of Linux and Linux-based operating systems security looks like, and it addresses the concerns of security enthusiasts, while exploring new uncharted area of security that have been looked at as a not so significant part of protecting the OSes out of concern of the various limitations and problems it entails. This research will address these concerns while exploring few ways to solve them, as well as addressing the ideal areas and situations in which the proposed method can be used, and when would such method be more of a burden than help if used.
On a regular basis, we hear of well-known online services that have been abused or compromised as a result of data theft. Because insecure applications jeopardize users' privacy as well as the reputation of corporations and organizations, they must be effectively secured from the outset of the development process. The limited expertise and experience of involved parties, such as web developers, is frequently cited as a cause of risky programs. Consequently, they rarely have a full picture of the security-related decisions that must be made, nor do they understand how these decisions affect implementation accurately.
The selection of tools and procedures that can best assist a certain situation in order to protect an application against vulnerabilities is a critical decision. Regardless of the level of security that results from adhering to security standards, these factors inadvertently result in web applications that are insufficiently secured. JavaScript is a language that is heavily relied on as a mainstream programming language for web applications with several new JavaScript frameworks being released every year.
JavaScript is used on both the server-side in web applications development and the client-side in web browsers as well.
However, JavaScript web programming is based on a programming style in which the application developer can, and frequently must, automatically integrate various bits of code from third parties. This potent combination has resulted in a situation today where security issues are frequently exploited. These vulnerabilities can compromise an entire server if left unchecked. Even though there are numerous ad hoc security solutions for web browsers, client-side attacks are also popular. The issue is significantly worse on the server side because the security technologies available for server-side JavaScript application frameworks are nearly non-existent.
Consequently, this thesis focuses on the server-side aspect of JavaScript; the development and evaluation of robust server-side security technologies for JavaScript web applications. There is a clear need for robust security technologies and security best practices in server-side JavaScript that allow fine-grained security.
However, more than ever, there is this requirement of reducing the associated risks without hindering the web application in its functionality.
This is the problem that will be tackled in this thesis: the development of secure security practices and robust security technologies for JavaScript web applications, specifically, on the server-side, that offer adequate security guarantees without putting too many constraints on their functionality.
The identification of vulnerabilities is an important element of the software development process to ensure the security of software. Vulnerability identification based on the source code is a well studied field. To find vulnerabilities on the basis of a binary executable without the corresponding source code is more challenging. Recent research has shown how such detection can be performed statically and thus runtime efficiently by using deep learning methods for certain types of vulnerabilities.
This thesis aims to examine to what extent this identification can be applied sufficiently for a variety of vulnerabilities. Therefore, a supervised deep learning approach using recurrent neural networks for the application of vulnerability detection based on binary executables is used. For this purpose, a dataset with 50,651 samples of 23 different vulnerabilities in the form of a standardised LLVM Intermediate Representation was prepared. The vectorised features of a Word2Vec model were then used to train different variations of three basic architectures of recurrent neural networks (GRU, LSTM, SRNN). For this purpose, a binary classification was trained for the presence of an arbitrary vulnerability, and a multi-class model was trained for the identification of the exact vulnerability, which achieved an out-of-sample accuracy of 88% and 77%, respectively. Differences in the detection of different vulnerabilities were also observed, with non-vulnerable samples being detected with a particularly high precision of over 98%. Thus, the methodology presented allows an accurate detection of vulnerabilities, as well as a strong limitation of the analysis scope for further analysis steps.
In this work, an implementation of the somewhat homomorphic BV encryption scheme is presented. During the implementation, care was taken to ensure that the resulting program will be as efficient as possible i.e. fast and resource-saving. The basis for this is the work of Arndt Bieberstein, who implemented the BV scheme with respect to functionality. The presented implementation supports the basics of the BV scheme, namely (symmetric and asymmetric) encryption, decryption and evaluation of addition as well as multiplication. Additionally, it supports the encoding of positive and negative numbers, various gaussian sampling methods, basically infinitely large polynomial coefficients, the generation of suitable parameters for a use case, threading and relinearization to reduce the size of a ciphertext after multiplications. After presenting the techniques used in the implementation, it’s actual efficiency is determined by measuring the timings of the operations for various parameters.
Die vorliegende Arbeit beschäftigt sich mit der Nutzung von Reinforcement Learning in der Informationsbeschaffungs-Phase eines Penetration Tests. Es werden Kernprobleme in den bisherigen Ansätzen anderer das Thema betreffender wissenschaftlicher Arbeiten analysiert und praktische Lösungsansätze für diese bisherigen Hindernisse vorgestellt und implementiert. Die Arbeit zeigt damit eine beispielhafte Implementierung eines Reinforcement Learning Agenten zur Automatisierung der Informationsbeschaffungs-Phase eines Penetration Tests und stellt Lösungen für existierende Probleme in diesem Bereich dar.
Eingebettet wird diese wissenschaftliche Arbeit in die Anforderungen der Herrenknecht AG hinsichtlich der Absicherung des Tunnelbohrmaschinen-Netzwerks. Dabei werden praktische Ergebnisse des eigen entwickelten Reinforcement Learning Modells im Tunnelbohrmaschinen-Test-Netzwerk der Herrenknecht AG vorgestellt.
Annotated training data is essential for supervised learning methods. Human annotation is costly and laborsome especially if a dataset consists of hundreds of thousands of samples and annotators need to be hired. Crowdsourcing emerged as a solution that makes it easier to get access to large amounts of human annotators. Introducing paid external annotators however introduces malevolent annotations, both intentional and unintentional. Both forms of malevolent annotations have negative effects on further usage of the data and can be summarized as spam. This work explores different approaches to post-hoc detection of spamming users and which kinds of spam can be detected by them. A manual annotation checking process resulted in the creation of a small user spam dataset which is used in this thesis. Finally an outlook for future improvements of these approaches will be made.
Among the billions of smartphone users in the world, Android still holds more than 80% of the market share. The applications which the users install have a specific set of features that need access to some device functionalities and sensors that may hold sensitive information about the user. Therefore, Android releases have set permission standards to let the user know what information is being disclosed to the application. Along with other security and privacy improvements, significant changes to the permission scheme are introduced with the Android 6.0 version (API level 23). In this master thesis, the Android permission scheme is tested on two devices from different eras. The evolution of Android over the years is examined in terms of confidentiality. For each device, two applications are built; one focused on extracting every piece of information within the confidentiality scope with every permission declared and/or requested, and the other app focused on getting this type of information without user notification. The resulting analysis illustrates whether how and in what way the Android permission scheme declined or improved over time.
Mobile Anwendungen werden im beruflichen Umfeld immer häufiger eingesetzt und dienen als praktische Helfer für Vertriebsmitarbeiter oder im Kundendienst. Dagegen ist ein Einsatz in der Baubranche ein recht neues Feld. Die tägliche Erfassung der Leistungsergebnisse einer Baustelle samt Geräteeinsatz, Mitarbeiterstunden, Lieferungen und Wetterdaten in Tagesberichten wird von vielen Bauunternehmen bisher noch auf Papier erledigt und später von Hand in ein Verwaltungsprogramm übertragen. Die Dokumentation direkt vor Ort mit einem mobilen Endgerät bietet den Vorteil, dass die Daten sofort verfügbar sind und auch besser ausgewertet werden können. Im Rahmen der vorliegenden Masterthesis wird nun in Zusammenarbeit mit dem Bauunternehmen Grafmüller untersucht, wie eine mobile Anwendung zu diesem Zweck aussehen kann. Dabei werden zunächst die Betriebsdatenerfassung im Allgemeinen und die Hintergründe der mobilen Anwendungsentwicklung analysiert. Dies dient dann als Basis für die Konzeption und die Umsetzung der Anwendung. Dabei werden bereits existierende Konkurrenzprodukte und die aktuelle Situation der Tagesberichtserstellung betrachtet. Besonderes Augenmerk liegt auf der plattformunabhängigen Entwicklung. Dazu wird der Einsatz von Webtechnologien zur Erstellung von hybriden Apps mit Hilfe entsprechender Werkzeuge untersucht. Die Umsetzung selbst beinhaltet den generellen Aufbau der mobilen Anwendung auf Basis eines hybriden App-Frameworks. Dazu zählt die persistente Datenspeicherung und die Synchronisation mit einer Administrationsanwendung sowie weitere Zusatzfunktionen, die gerätespezifische Eigenschaften nutzen, beispielsweise GPS.