Οι επιθέσεις στο Διαδίκτυο και ειδικά οι επιθέσεις άρνησης εξυπηρέτησης (Denial of Service, DoS) αποτελούν ένα πολύ σοβαρό πρόβλημα για την ομαλή λειτουργία του Διαδικτύου. Αυτό το είδος επιθέσεων στοχεύει στην διατάραξη της καλής λειτουργίας ενός συστήματος, καταναλώνοντας τους πόρους του ή προκαλώντας υπερφόρτωση στο δίκτυο, καθιστώντας το ανίκανο να παρέχει στους πελάτες του τις υπηρεσίες για τις οποίες προορίζεται. Η αντιμετώπιση των επιθέσεων αυτών έχει απασχολήσει πολλούς ερευνητές τα τελευταία χρόνια και έχουν προταθεί πολλές διαφορετικές μέθοδοι πρόληψης, ανίχνευσης, και απόκρισης. Στα πλαίσια της παρούσας διπλωματικής επιχειρείται αρχικά ο ορισμός και η ταξινόμηση των επιθέσεων DoS και DDoS, με ιδιαίτερη αναφορά στις επιθέσεις DoS στον Παγκόσμιο Ιστό. Στη συνέχεια αναλύονται διάφοροι τρόποι αναγνώρισης επιθέσεων, με κύριους άξονες την αναγνώριση υπογραφής και την ανίχνευση ανωμαλιών. Γίνεται εμβάθυνση στο πεδίο της ανίχνευσης ανωμαλιών και πραγματοποιείται η μελέτη ενός συστήματος που ανιχνεύει ανωμαλίες σε δεδομένα κίνησης δικτύου που περιέχουν επιθέσεις. / Attacks in the Internet, and especially Denial of Service attacks, are a very serious threat to the normal function of the Internet. This kind of attack aims to the disruption of the normal function of a system, by consuming its resources or overloading the network, making it incapable to provide services, that is designed for, to the clients. In recent years many researchers have tried to propose solutions to prevent, detect and respond effectively to attacks. In this thesis, first a definition, and then a classification of DoS and DDoS attacks is proposed, with distinctive reference to attacks in the World Wide Web. Several ways of attack detection are analyzed, with signature detection and anomaly detection being the most significant. Afterwards, the field of anomaly detection is thoroughly analyzed, and a system that detects anomalies to a dataset of network traffic that contains attacks, is examined.

A large amount of today's communication occurs within data centers where a large number of virtual servers (running one or more virtual machines) provide service providers with the infrastructure needed for their applications and services. In this thesis, we will look at the next step in the virtualization revolution, the virtualized network. Software-defined networking (SDN) is a relatively new concept that is moving the field towards a more software-based solution to networking. Today when a packet is forwarded through a network of routers, decisions are made at each router as to which router is the next hop destination for the packet. With SDN these decisions are made by a centralized SDN controller that decides upon the best path and instructs the devices along this path as to what action each should perform. Taking SDN to its extreme minimizes the physical network components and increases the number of virtualized components. The reasons behind this trend are several, although the most prominent are simplified processing and network administration, a greater degree of automation, increased flexibility, and shorter provisioning times. This in turn leads to a reduction in operating expenditures and capital expenditures for data center owners, which both drive the further development of this technology. Virtualization has been gaining ground in the last decade. However, the initial introduction of virtualization began in the 1970s with server virtualization offering the ability to create several virtual server instances on one physical server. Today we already have taken small steps towards a virtualized network by virtualization of network equipment such as switches, routers, and firewalls. Common to virtualization is that it is in early stages all of the technologies have encountered trust issues and general concerns related to whether software-based solutions are as rugged and reliable as hardwarebased solutions. SDN has also encountered these issues, and discussion of these issues continues among both believers and skeptics. Concerns about trust remain a problem for the growing number of cloud-based services where multitenant deployments may lead to loss of personal integrity and other security risks. As a relatively new technology, SDN is still immature and has a number of vulnerabilities. As with most software-based solutions, the potential for security risks increases. This thesis investigates how denial-of-service (DoS) attacks affect an SDN environment and a singlethreaded controller, described by text and via simulations. The results of our investigations concerning trust in a multi-tenancy environment in SDN suggest that standardization and clear service level agreements are necessary to consolidate customers’ confidence. Attracting small groups of customers to participate in user cases in the initial stages of implementation can generate valuable support for a broader implementation of SDN in the underlying infrastructure. With regard to denial-of-service attacks, our conclusion is that hackers can by target the centralized SDN controller, thus negatively affect most of the network infrastructure (because the entire infrastructure directly depends upon a functioning SDN controller). SDN introduces new vulnerabilities, which is natural as SDN is a relatively new technology. Therefore, SDN needs to be thoroughly tested and examined before making a widespread deployment. / Dagens kommunikation sker till stor del via serverhallar där till stor grad virtualiserade servermiljöer förser serviceleverantörer med infrastukturen som krävs för att driva dess applikationer och tjänster. I vårt arbete kommer vi titta på nästa steg i denna virtualiseringsrevolution, den om virtualiserade nätverk. mjukvarudefinierat nätverk (eng. Software-defined network, eller SDN) kallas detta förhållandevis nya begrepp som syftar till mjukvarubaserade nätverk. När ett paket idag transporteras genom ett nätverk tas beslut lokalt vid varje router vilken router som är nästa destination för paketet, skillnaden i ett SDN nätverk är att besluten istället tas utifrån ett fågelperspektiv där den bästa vägen beslutas i en centraliserad mjukvaruprocess med överblick över hela nätverket och inte bara tom nästa router, denna process är även kallad SDN kontroll. Drar man uttrycket SDN till sin spets handlar det om att ersätta befintlig nätverksutrustning med virtualiserade dito. Anledningen till stegen mot denna utveckling är flera, de mest framträdande torde vara; förenklade processer samt nätverksadministration, större grad av automation, ökad flexibilitet och kortare provisionstider. Detta i sin tur leder till en sänkning av löpande kostnader samt anläggningskostnader för serverhallsinnehavare, något som driver på utvecklingen. Virtualisering har sedan början på 2000-talet varit på stark frammarsch, det började med servervirtualisering och förmågan att skapa flertalet virtualiserade servrar på en fysisk server. Idag har vi virtualisering av nätverksutrustning, såsom switchar, routrar och brandväggar. Gemensamt för all denna utveckling är att den har i tidigt stadie stött på förtroendefrågor och överlag problem kopplade till huruvida mjukvarubaserade lösningar är likvärdigt robusta och pålitliga som traditionella hårdvarubaserade lösningar. Detta problem är även något som SDN stött på och det diskuteras idag flitigt bland förespråkare och skeptiker. Dessa förtroendefrågor går på tvären mot det ökande antalet molnbaserade tjänster, typiska tjänster där säkerheten och den personliga integriten är vital. Vidare räknar man med att SDN, liksom annan ny teknik medför vissa barnsjukdomar såsom kryphål i säkerheten. Vi kommer i detta arbete att undersöka hur överbelastningsattacker (eng. Denial-of-Service, eller DoS-attacker) påverkar en SDN miljö och en singel-trådig kontroller, i text och genom simulering. Resultatet av våra undersökningar i ämnet SDN i en multitenans miljö är att standardisering och tydliga servicenivåavtal behövs för att befästa förtroendet bland kunder. Att attrahera kunder för att delta i mindre användningsfall (eng. user cases) i ett inledningsskede är också värdefullt i argumenteringen för en bredare implementering av SDN i underliggande infrastruktur. Vad gäller DoS-attacker kom vi fram till att det som hackare går att manipulera en SDN infrastruktur på ett sätt som inte är möjligt med dagens lösningar. Till exempel riktade attacker mot den centraliserade SDN kontrollen, slår man denna kontroll ur funktion påverkas stora delar av infrastrukturen eftersom de är i ett direkt beroende av en fungerande SDN kontroll. I och med att SDN är en ny teknik så öppnas också upp nya möjligheter för angrepp, med det i åtanke är det viktigt att SDN genomgår rigorösa tester innan större implementation.

Thesis( M. A. (Computer Science)) -- University of Limpopo , 2021 / In Software Defined Cognitive Radio Network (SDCRN), network security is a significant issue. This issue arises when Software Defined Network (SDN) architecture integrates with the Cognitive Radio Network (CRN) technology. SDN is designed to improve network resource management, while CRN technology is meant at improving spectrum management. These technologies are vulnerable to several malicious attacks. These attacks include Distributed Denial of Service (DDoS) and Primary User Emulation (PUE). Both the DDoS and PUE can be disrupt services in the SDCRN. To curb these attacks, schemes which hardens the security of SDCRN need to be designed. Thus, in this study we propose a security mechanism called Extreme_Controller_Mechanism (XCM) that reduce the effects of DDoS and PUE. The proposed XCM scheme was designed and evaluated in three simulation environment, the OMNeT++, Octave, and MATLAB simulators. The SDCRN data set was generated using the Neural Network back propagation algorithms. The data set was then used in Matlab to evaluate the effectiveness of the prosed XCM scheme. XCM proved to be effective and efficient at detection and prevention of DDoS and PUE attacks in SDCRN. In terms of memory and processor utilisation, XCM proved to the best when compared to other schemes such as the Advanced Support Vector Machine (ASVM) and deep learning convolution network (CDLN). But in terms of detection time, the ASVM was found to be the best performing scheme. Regarding our test for detection rate, false positive and false negative, the XCM, ASVM and CDLM performed the same. The results of the XCM were therefore the best and superior to the ASVM and CDLM. This can be attributed to the fact that the XCM scheme is optimised for DDoS and PUE attacks. We can therefore conclude that our XCM scheme is the best performing scheme compared to the ASVM and CDLN schemes.

No description available.

As the financial sector has become increasingly digitized, its vulnerability to cyberattacks has increased. Distributed Denial of Service attacks are one of the biggest threats on the internet today and has been growing steadily for the last few years. The increase applies to both the size and frequency of the attacks. DDoS-attacks have been a threat especially towards banks and therefore it is important to have a well functional cyber security strategy to withstand the attacks. This thesis investigates Swedish banks perception regarding the threat picture of DDoS-attacks against banks. As a result of a qualitative case study, Swedish banks opinion has been investigated through interviews with IT security managers at Swedish banks. The banks are considered to have effective strategies to prevent and manage DDoS-attacks but the threat of cyber attacks continues to increase. The participants mention various factors that show an increase in DDoS-attacks and the media can be an influence. The empirical material is analyzed using the National Cybersecurity Strategy (NCSS) framework developed by the European Union Agency for Cybersecurity (ENISA).

No description available.

With the current proliferation of cyber attacks, safeguarding internet facing assets from network intrusions, is becoming a vital task in our increasingly digitalised economies. Although recent successes of machine learning (ML) models bode the dawn of a new generation of intrusion detection systems (IDS); current solutions struggle to implement these in an efficient manner, leaving many IDSs to rely on rule-based techniques. In this paper we begin by reviewing the different approaches to feature construction and attack source identification employed in such applications. We refer to these steps as the framework within which models are implemented, and use it as a prism through which we can identify the challenges different solutions face, when applied in modern network traffic conditions. Specifically, we discuss how the most popular framework -- the so called flow-based approach -- suffers from significant overhead being introduced by its resource heavy pre-processing step. To address these issues, we propose the Information Theoretic Framework for Network Anomaly Detection (ITF-NAD); whose purpose is to facilitate online application of statistical learning models onto high-speed network links, as well as provide a method of identifying the sources of traffic anomalies. Its development was inspired by previous work on information theoretic-based anomaly and outlier detection, and employs modern techniques of entropy estimation over data streams. Furthermore, a case study of the framework's detection performance over 5 different types of Denial of Service (DoS) attacks is undertaken, in order to illustrate its potential use for intrusion detection and mitigation. The case study resulted in state-of-the-art performance for time-anomaly detection of single source as well as distributed attacks, and show promising results regarding its ability to identify underlying sources. / I takt med att antalet cyberattacker växer snabbt blir det alltmer viktigt för våra digitaliserade ekonomier att skydda uppkopplade verksamheter från nätverksintrång. Maskininlärning (ML) porträtteras som ett kraftfullt alternativ till konventionella regelbaserade lösningar och dess anmärkningsvärda framgångar bådar för en ny generation detekteringssytem mot intrång (IDS). Trots denna utveckling, bygger många IDS:er fortfarande på signaturbaserade metoder, vilket förklaras av de stora svagheter som präglar många ML-baserade lösningar. I detta arbete utgår vi från en granskning av nuvarande forskning kring tillämpningen av ML för intrångsdetektering, med fokus på de nödvändiga steg som omger modellernas implementation inom IDS. Genom att sätta upp ett ramverk för hur variabler konstrueras och identifiering av attackkällor (ASI) utförs i olika lösningar, kan vi identifiera de flaskhalsar och begränsningar som förhindrar deras praktiska implementation. Särskild vikt läggs vid analysen av de populära flödesbaserade modellerna, vars resurskrävande bearbetning av rådata leder till signifikant tidsfördröjning, vilket omöjliggör deras användning i realtidssystem. För att bemöta dessa svagheter föreslår vi ett nytt ramverk -- det informationsteoretiska ramverket för detektering av nätverksanomalier (ITF-NAD) -- vars syfte är att möjliggöra direktanslutning av ML-modeller över nätverkslänkar med höghastighetstrafik, samt tillhandahåller en metod för identifiering av de bakomliggande källorna till attacken. Ramverket bygger på modern entropiestimeringsteknik, designad för att tillämpas över dataströmmar, samt en ASI-metod inspirerad av entropibaserad detektering av avvikande punkter i kategoriska rum. Utöver detta presenteras en studie av ramverkets prestanda över verklig internettrafik, vilken innehåller 5 olika typer av överbelastningsattacker (DoS) genererad från populära DDoS-verktyg, vilket i sin tur illustrerar ramverkets användning med en enkel semi-övervakad ML-modell. Resultaten visar på hög nivå av noggrannhet för detektion av samtliga attacktyper samt lovande prestanda gällande ramverkets förmåga att identifiera de bakomliggande aktörerna.

E-crimes continue to generate grave challenges to the ICT regulatory agenda. Because e-crimes involve a wrongful appropriation of information online, it is enquired whether information is property which is capable of being stolen. This then requires an investigation to be made of the law of property. The basis for this scrutiny is to establish if information is property for purposes of the law. Following a study of the Roman-Dutch law approach to property, it is argued that the emergence of an information society makes real rights in information possible. This is the position because information is one of the indispensable assets of an information society. Given the fact that information can be the object of property, its position in the law of theft is investigated. This study is followed by an examination of the conventional risks that ICTs generate. For example, a risk exists that ICTs may be used as the object of e-crimes. Furthermore, there is a risk that ICTs may become a tool in order to appropriate information unlawfully. Accordingly, the scale and impact of e-crimes is more than those of the offline crimes, for example theft or fraud. The severe challenges that ICTs pose to an information society are likely to continue if clarity is not sought regarding: whether ICTs can be regulated or not, if ICTs can be regulated, how should an ICT regulatory framework be structured? A study of the law and regulation for regulatory purposes reveals that ICTs are spheres where regulations apply or should apply. However, better regulations are appropriate in dealing with the dynamics of these technologies. Smart-regulations, meta-regulations or reflexive regulations, self-regulations and co-regulations are concepts that support better regulations. Better regulations enjoin the regulatory industries, for example the state, businesses and computer users to be involved in establishing ICT regulations. These ICT regulations should specifically be in keeping with the existing e-authentication measures. Furthermore, the codes-based theory, the Danger or Artificial Immune Systems (the AIS) theory, the Systems theory and the Good Regulator Theorem ought to inform ICT regulations. The basis for all this should be to establish a holistic approach to e-authentication. This approach must conform to the Precautionary Approach to E-Authentication or PAEA. PAEA accepts the importance of legal rules in the ICT regulatory agenda. However, it argues that flexible regulations could provide a suitable framework within which ICTs and the ICT risks are controlled. In addition, PAEA submit that a state should not be the single role-player in ICT regulations. Social norms, the market and nature or architecture of the technology to be regulated are also fundamental to the ICT regulatory agenda. / Jurisprudence / LL. D.