Medeiros, Ibéria Vitória de Sousa, 1971-Respício, Ana Luísa do Carmo Correia, 1965-Ramires, Rafael Francisco Rosa Mesquita2023-08-242023-08-2420232023http://hdl.handle.net/10451/58991Tese de mestrado, Engenharia Informática, 2023, Universidade de Lisboa, Faculdade de CiênciasThe increasing reliance on the web for various applications has led to an increase in the number of web-based attacks and vulnerabilities. When exploited, such vulnerabilities as Cross-site Scripting (XSS) and SQL injection (SQLi) can cause severe damage to companies, such as theft of vast amounts of user credentials and access to undue data. One of the most used methods to detect web vulnerabilities is static analysis, which analyzes all application code without running it, which is beneficial so the code can be corrected prior to execution, but at the same time a complex task. This dissertation presents a novel approach for detecting vulnerabilities in PHP web applications by developing a knowledge-based agent-system vulnerability detector (KAVe). The system aims to improve upon existing vulnerability detection tools by incorporating knowledge graphs generated by combining the most important part of multiple code property graphs to be then navigated by a multi-agent system that will perform taint analysis to efficiently identify potential security weaknesses. The study objectives include code parsing and analysis, graph construction, knowledge graph creation, graph pruning, multi-agent navigation, vulnerability detection, validation, and comparison with existing tools. The results demonstrate that KAVe provides a more effective and efficient method for detecting vulnerabilities in PHP web applications, contributing to the web security field and offering a valuable tool for developers and security professionals. The tool found 169 vulnerabilities over 12 open-source web applications, with a precision of 98.81%.engvulnerabilidades em aplicações webanálise estáticagrafos de propriedades de funçõesgrafos de conhecimentosistemas multiagenteTeses de mestrado - 2023master thesis203491904