This final essay discussed the pentesting process and described the necessary steps when it comes to testing Windows systems. The pentesting process ranged from phase of setting up a virtual lab, information gathering phase, evaluation, exploitation, and ended with the post exploitation phase. In the initial phase, efforts were made to simulate the Windows environment in VmWare, install Kali linux and the necessary pentesting tools. This was followed by a phase of information gathering in which an attempt was made to find out as much as possible about the subject for which pentesting is performed such as domains he has registered, subdomains, portable zones if any exist and port scanning. The assessment phase was aimed at identifying the weaknesses that the windows system possesses for particular software, web application weaknesses and other information leading to system compromise. After that, the exploitation phase started, where all previously discovered weaknesses are exploited. The process of software engineering, client-side exploitation, and bypassing antivirus applications were also described here. Informations acquired in the previous stage rely on an exploitation phase that describes how to manage the system's privileges and how further raise them to endanger the safety of the victim's system.