A hacker can potentially gain access to an unprotected system in under 15 seconds by exploiting security flaws. The document outlines how to check if a system is vulnerable by using command line tools to view the system's IP address and network configuration. It finds that if the system has a hex code of <20>, it indicates file and printer sharing is enabled, allowing hackers easy access. The guide aims to educate users on vulnerabilities so they can better protect themselves from online threats.