Sentry: Uma Contramedida Adaptativa contra Ataques de Negação de Serviço de Baixo Volume
Resumo
Algoritmos estáticos de aprendizado de máquina tornam os sistemas de detecção de intrusão ineficazes em ambientes dinâmicos, uma vez que esses sistemas permanecem restritos aos padrões de dados observados durante a fase de treinamento. Este artigo propõe o Sentry, uma contramedida adaptativa baseada no algoritmo Online Isolation Forest, voltada à identificação de ataques de negação de serviço de baixo volume em redes definidas por software. O Sentry realiza atualizações contínuas e incorpora critérios seletivos condicionados ao estado da rede, evitando aprendizado inadequado durante períodos de ataque e reduzindo o risco de contaminação do modelo. A avaliação experimental demonstra que o Sentry supera tanto o Online Isolation Forest com atualizações irrestritas quanto o XGBoost. O Sentry atinge métricas de revocação e pontuação F1 de até 98,89% e 98,53%, respectivamente. Em contrapartida, o XGBoost e o Online Isolation Forest exibem uma queda acentuada no desempenho, com a revocação caindo para 17,95% e 10,50%, respectivamente.
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