The rule 'List Open Egress Ports' is designed to detect the potential risk associated with outbound port traffic within a network. It specifically monitors for outbound connections through a defined set of the 128 most commonly used Internet ports, as specified by the Nmap project. By identifying outbound port scans, the rule aims to minimize the risk by ensuring that unauthorized data flows do not occur through common exit points which could be exploited by attackers. It utilizes Windows event logs with event ID 5156 to track this data. The rule complicates egress monitoring with conditions that only allow outbound traffic that is not targeting internal or private address spaces, thereby focusing on potentially malicious behaviors. It groups events to ensure that the same host/process does not repeatedly trigger the detection in a short time frame, limiting false positives. This detection aligns with techniques focused on network service and system network connections discovery which indicates its relevance in identifying reconnaissance activities by threat actors.