ATT&CK T1021.004 - Internal SSH Lateral Movement

This rule detects potential internal SSH lateral movement attempts. It triggers an alert when there are 5 or more TCP SYN packets (indicating connection attempts) to port 22 (SSH) within a 60-second window, originating from a host within the home network and targeting another host within the home network. This threshold-based detection aims to identify rapid, repeated SSH connection attempts that could signify an attacker trying to move between internal systems.