Analytical Lifecycle Modeling and Threat Analysis of Botnets

Botnet, which is an overlay network of compromised computers built by cybercriminals known as botmasters, is the new phenomenon that has caused deep concerns to the security professionals responsible for governmental, academic, and private sector networks. Botmasters use a plethora of methods to infect network-accessible devices (nodes). The initial malware residing on these nodes then either connects to a central Command & Control (C&C) server or joins a Peer-to-Peer (P2P) botnet. At this point, the nodes can receive the commands of the botmaster and proceed to engage in illicit activities such as Distributed Denial-of-Service (DDoS) attacks and massive e-mail spam campaigns. Being able to reliably estimate the size of a botnet is an important task which allows the adequate deployment of mitigation strategies against the botnet. In this thesis, we develop analytical models that capture the botnet expansion and size evolution behaviors in sufficient details so as to accomplish this crucial estimation/analysis task. We develop four Continuous-Time Markov Chain (CTMC) botnet models: the first two, SComI and SComF, allow the prediction of initial unhindered botnet expansion in the case of infinite and finite population sizes, respectively. The third model, the SIC model, is a botnet lifecycle model which accounts for all important node stages and allows botnet size estimates as well as evaluation of botnet mitigation strategies such as disinfections of nodes and attacks on botnet's C&C mechanism. Finally, the fourth model, the SIC-P2P model, is an extension of the SIC model suitable for P2P botnets, allowing fine-grained analysis of mitigation strategies such as index poisoning and sybil attack. As the convergence of Internet and traditional telecommunication services is underway, the threat of botnets is looming over essential basic communication services. As the last contribution presented in this thesis, we analyze the threat of botnets in the 4G cellular wireless networks. We identify the vulnerability of the air interface, i.e. the Long Term Evolution (LTE), which allows a successful botnet-launched DDoS attack against it. Through simulation using an LTE simulator, we determine the number of botnet nodes per cell that can significantly degrade the service availability of such cellular networks

Snapshot of MAC, PHY and Propagation Models for IEEE 802.11 in Open-Source Network Simulators

Simulation is an essential component of the validation chain in the design of network protocols. Indeed, while simulation is not the only tool used for data networking research, it is extremely useful because it often allows research questions and prototypes to be explored at many orders-of-magnitude less cost and time than that required to experiment with real implementations and networks. In this report, we focus on the simulation of IEEE 802.11 Physical (PHY) and Medium Access Control (MAC) layers and provide a survey of current IEEE 802.11 network simulators. We believe that such survey will help network researchers to select the best simulator according to the requirements of their simulations. Furthermore, we present a detailed description of the YANS prototype network simulator, and especially its physical layer imple-mentation, which will be partly ported in the upcoming NS-3 network simulator

An energy and cost efficient majority-based RAM cell in quantum-dot cellular automata

Nanotechnologies, notably quantum-dot cellular automata, have achieved major attentions for their prominent features as compared to the conventional CMOS circuitry. Quantum-dot cellular automata, particularly owning to its considerable reduction in size, high switching speed and ultra-low energy consumption, is considered as a potential alternative for the CMOS technology. As the memory unit is one of the most essential components in a digital system, designing a well-optimized QCA random access memory (RAM) cell is an important area of research. In this paper, a new five-input majority gate is presented which is suitable for implementing efficient single-layer QCA circuits. In addition, a new RAM cell with set and reset capabilities is designed based on the proposed majority gate, which has an efficient and low-energy structure. The functionality, performance and energy consumption of the proposed designs are evaluated based on the QCADesigner and QCAPro tools. According to the simulation results, the proposed RAM design leads to on average 38% lower total energy dissipation, 25% smaller area, 20% lower cell count, 28% lower delay and 60% lower QCA cost as compared to its previous counterparts. Keywords: Quantum-dot cellular automata (QCA), Majority gate, Random access memory (RAM), Energy efficienc

Quantum-Dot Cellular Automata Circuits With Reduced External Fixed Inputs

Nanotechnologies, notably quantum-dot cellular automata, have achieved world-wide attentions for their prominent features as compared to the conventional CMOS circuitry. Quantum-dot cellular automata, particularly owning to its considerable reduction in size, energy consumption and latency of circuits, is considered as a potential alternative for the CMOS technology. Considering the manufacturing aspects, in this paper, a method is proposed for designing efficient quantum-dot cellular automata circuits. We inspect an alternative approach for streamlined design of quantum-dot cellular automata circuits such that the required external fixed inputs are substantially reduced. In order to demonstrate the efficiency of the proposed method, the widely used multiplexer, XOR and party generator circuits are considered as case studies. All of the proposed circuits are simulated and verified using QCADesigner which is a valid and popular simulation tool. Comparisons indicate that the proposed method considerably reduces the number of external fixed inputs which simplifies the overall circuit implementation and fabrication

Polymerase Chain Reaction Assay Using the Restriction Fragment Length Polymorphism Technique in the Detection of Prosthetic Joint Infections: A Multi-Centered Study

Background: PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) techniques have been used for the diagnosis of bacteria in some infections. In this study, we aimed to evaluate the diagnostic accuracy of PCR for the diagnosis of prosthetic joint infections (PJI) and to identify isolated microorganisms, using the RFLP method. Methods: During January 2015 to January 2018, patients who were suspected of having PJI after arthroplasty surgery or were candidates for revision surgery due to loosening of implant entered the study. Patients who had 1 major criterion or 3 minor criteria for PJI based on the Philadelphia Consensus Criteria (PCC) on Periprosthetic Joint Infection were considered as cases of PJI. Both culture results and PCR findings, were cross compared with results of the PCC (as the gold standard criteria). Results: Overall, 76 samples were included in the study. Mean (standard deviation) age of patients was 66.72 ± 11.82 years. Overall, 57.9 of patients were females. Prevalence of PJI was 50 based on the PCC. Sensitivity, specificity, positive predictive value, negative predictive value, and general efficacy of PCR for detection of PJI was 97.4, 100, 100, 97.4, and 98.7, respectively. Sensitivity, specificity, positive predictive value, negative predictive value, and general efficacy of culture was 31.6, 100, 65.7, 100, and 59.4, respectively. We isolated a broad range of bacteria using PCR-RFLP including Gram-positive cocci such as Staphylococcus sp., Streptococcus sp., and Enterococcus sp., and Gram-negative bacilli such as Enterobacteriaceae sp., Pseudomonas sp. Citrobacter sp., as well as Chlamydophila pneumonia, Stenotrophomonas maltophilia, Brucella melitensis, non-gonococcal Neisseria, Kingella kingae, Bacteroides ovatus, and Proteus mirabilis from PJI patients. Conclusion: Inhere, for the first time, we showed that PCR-RFLP is a powerful tool for identifying the type of bacteria involved in PJI, and can be used for follow-up of patients suspected of PJI and those with a history of antibiotic use. PCR-RFLP may be able to substantially decrease detection time of PJI among PCR-based methods, while allowing more accurate identification of the bacteria involved. © 2018 Elsevier Inc