In recent years, the accelerated growth of Internet of Things (IoT) technology has brought with it a proliferation of devices that, while improving the quality of life, also introduce serious security vulnerabilities. This paper presents a systematic literature review of the pentesting methods used to identify and mitigate vulnerabilities in IoT devices. It discusses how penetration testing is fundamental to assessing security and analyze various existing methodologies and frameworks. Through an approach based on the PICOC methodology, a set of studies exploring IoT device security interventions were identified and analyzed, revealing both the most common vulnerabilities and techniques used for their evaluation. The analysis of these tests and methodologies has provided insights into the current state of this type of testing, revealing that there are areas for improvement relative to the automation of certain processes when identifying vulnerabilities. Having a standardized framework to perform pentesting tests would help ensure the security of IoT devices; in turn, the implementation of tools facilitates vulnerability assessment tasks in terms of reducing time and detecting vulnerabilities.