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Publicações

Publicações por CRACS

2025

A Risk Manager for Intrusion Tolerant Systems: Enhancing HAL 9000 With New Scoring and Data Sources

Autores
Freitas, T; Novo, C; Dutra, I; Soares, J; Correia, ME; Shariati, B; Martins, R;

Publicação
SOFTWARE-PRACTICE & EXPERIENCE

Abstract
Background Intrusion Tolerant Systems (ITS) aim to maintain system security despite adversarial presence by limiting the impact of successful attacks. Current ITS risk managers rely heavily on public databases like NVD and Exploit DB, which suffer from long delays in vulnerability evaluation, reducing system responsiveness.Objective This work extends the HAL 9000 Risk Manager to integrate additional real-time threat intelligence sources and employ machine learning techniques to automatically predict and reassess vulnerability risk scores, addressing limitations of existing solutions.Methods A custom-built scraper collects diverse cybersecurity data from multiple Open Source Intelligence (OSINT) platforms, such as NVD, CVE, AlienVault OTX, and OSV. HAL 9000 uses machine learning models for CVE score prediction, vulnerability clustering through scalable algorithms, and reassessment incorporating exploit likelihood and patch availability to dynamically evaluate system configurations.Results Integration of newly scraped data significantly enhances the risk management capabilities, enabling faster detection and mitigation of emerging vulnerabilities with improved resilience and security. Experiments show HAL 9000 provides lower risk and more resilient configurations compared to prior methods while maintaining scalability and automation.Conclusions The proposed enhancements position HAL 9000 as a next-generation autonomous Risk Manager capable of effectively incorporating diverse intelligence sources and machine learning to improve ITS security posture in dynamic threat environments. Future work includes expanding data sources, addressing misinformation risks, and real-world deployments.

2025

Next Higher Point: Two Novel Approaches for Computing Natural Visibility Graphs

Autores
Daniel, P; Silva, VF; Ribeiro, P;

Publicação
COMPLEX NETWORKS & THEIR APPLICATIONS XIII, COMPLEX NETWORKS 2024, VOL 1

Abstract
With the huge amount of data that has been collected over time, many methods are being developed to allow better understanding and forecasting in several domains. Time series analysis is a powerful tool to achieve this goal. Despite being a well-established area, there are some gaps, and new methods are emerging to overcome these limitations, such as visibility graphs. Visibility graphs allow the analyses of times series as complex networks and make possible the use of more advanced techniques from another well-established area, network science. In this paper, we present two new efficient approaches for computing natural visibility graphs from times series, one for online scenarios in.O(n log n) and the other for offline scenarios in.O(nm), the latter taking advantage of the number of different values in the time series (m).

2025

Studying and Improving Graph Neural Network-based Motif Estimation

Autores
Vieira, PC; Silva, MEP; Pinto Ribeiro, PM;

Publicação
CoRR

Abstract

2025

Evaluating Transfer Learning Methods on Real-World Data Streams: A Case Study in Financial Fraud Detection

Autores
Pereira, RR; Bono, J; Ferreira, HM; Ribeiro, P; Soares, C; Bizarro, P;

Publicação
Machine Learning and Knowledge Discovery in Databases. Applied Data Science Track - European Conference, ECML PKDD 2025, Porto, Portugal, September 15-19, 2025, Proceedings, Part IX

Abstract
When the available data for a target domain is limited, transfer learning (TL) methods leverage related data-rich source domains to train and evaluate models, before deploying them on the target domain. However, most TL methods assume fixed levels of labeled and unlabeled target data, which contrasts with real-world scenarios where both data and labels arrive progressively over time. As a result, evaluations based on these static assumptions may not reflect how methods perform in practice. To support a more realistic assessment of TL methods in dynamic settings, we propose an evaluation framework that (1) simulates varying data availability over time, (2) creates multiple domains via resampling of a given dataset and (3) introduces inter-domain variability through controlled transformations, e.g., including time-dependent covariate and concept shifts. These capabilities enable the systematic simulation of a large number of variants of the experiments, providing deeper insights into how algorithms may behave when deployed. We demonstrate the usefulness of the proposed framework by performing a case study on a proprietary real-world suite of card payment datasets. To support reproducibility, we also apply the framework on the publicly available Bank Account Fraud (BAF) dataset. By providing a methodology for evaluating TL methods over time and in different data availability conditions, our framework supports a better understanding of model behavior in real-world environments, which enables more informed decisions when deploying models in new domains. © 2025 Elsevier B.V., All rights reserved.

2025

On Exploring Safe Memory Reclamation Methods with a Simplified Lock-Free Hash Map Design

Autores
Moreno, P; Areias, M; Rocha, R;

Publicação
EURO-PAR 2024: PARALLEL PROCESSING WORKSHOPS, PT II

Abstract
Lock-freedom offers significant advantages in terms of algorithm design, performance and scalability. A fundamental building block in software development is the usage of hash map data structures. This work extends a previous lock-free hash map to support a new simplified design that is able to take advantage of most state-of-the-art safe memory reclamation methods, thus outperforming the previous design.

2025

6th International Computer Programming Education Conference, ICPEC 2025, July 10-11, 2025, PORTIC, Polytechnic of Porto, Portugal

Autores
Queirós, R; Pinto, M; Portela, F; Simões, A;

Publicação
ICPEC

Abstract

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