Decision trees are one of the most popular structures for decision-making and the representation of a set of rules. However, when a rule set is represented as a decision tree, some quirks in its structure may negatively affect its performance. For example, duplicate sub-trees and rule filters, that need to be evaluated more than once, could negatively affect the efficiency. This paper presents a novel algorithm based on Shannon’s expansion, which guarantees that the same rule filter is not evaluated more than once, even if repeated in other rules. This fact increases efficiency during the evaluation process using the induced decision tree. Experiments demonstrated the viability of the proposed algorithm in processing-intensive scenarios, such as in intrusion detection and data stream analysis.@en

We live in a world that is being driven by data. This leads to challenges of extracting and analyzing knowledge from large volumes of data. An example of such a challenge is intrusion detection. Intrusion detection data sets are characterized by huge volumes, which affects the learning of the classifier. So there is a need to reduce the size of the training sets. Fortunately, inspection and analysis of available intrusion detection data sets showed that many instances are very similar and do not provide relevant information to the classification process. This prompted to look for possibilities to use a fast algorithm that, as much as possible, removes similar instances in intrusion detection data sets while enforcing the detection rate. In this work, a new fast instance reduction algorithm is presented. The proposed algorithm provides greater efficiency during the training stage, without significantly affecting the efficacy during the intrusion detection task.

@en

Telecommunications services have become a constant in people’s lives. This has inspired fraudsters to carry out malicious activities causing economic losses to people and companies. Early detection of signs that suggest the possible occurrence of malicious activity would allow analysts to act in time and avoid unintended consequences. Modeling the behavior of users could identify when a significant change takes place. Following this idea, an algorithm for online behavior change detection in telecommunication services is proposed in this paper. The experimental results show that the new algorithm can identify behavioral changes related to unforeseen events.@en

Every day the number of devices interacting through telecommunications networks grows resulting into an increase in the volume of data and information generated. At the same time, a growing number of information security incidents is being observed including the occurrence of unauthorized accesses, also named intrusions. As a consequence of these two developments, Information and Communications services providers require automated processes to detect and solve such intrusions, and this should done quickly in order to keep the related cybersecurity risks at acceptable levels. However, the presence of large volumes of data negatively interferes with the performance of classifiers used in intrusion detection tasks, which limits their applicability in practical cases. The research reported in this paper focuses on proposing a novel feature selection algorithm for intrusion detection scenarios. To this end, an extensive literature review was executed to first discover issues in the feature selection algorithms reported. Based on the insights obtained, the new multi-measure feature selection algorithm was designed that uses qualitative information provided by multiple feature selection measures, and reduces the dimensionality of the training data set. The algorithm proposed was next extensively tested using various data sets. It provides greater efficacy than other feature selection algorithms used for intrusion detection purposes. We finalize by providing some ideas on future research in order to further improve the algorithm.

@en

In the last few years, the telecommunications scenario has experienced an increase in the volume of information generated, as well as in the execution of malicious activities. In order to complement Intrusion Detection Systems (IDSs), data mining techniques have begun to play a fundamental role in data analysis. On the other hand, the presence of useless information and the amount of data generated by telecommunication services (leading to a huge dimensional problem), can affect the performance of traditional IDSs. In this sense, a data preprocessing strategy is necessary to reduce data, but reducing data without affecting the accuracy of IDSs represents a challenge. In this paper, we propose a new data preprocessing strategy which reduces the number of features and instances in the training collection without greatly affecting the achieved accuracy of IDSs. Finally, our proposal is evaluated using four different rule-based classifiers, which are tested on real scan and backscatter data collected by a network telescope.

@en