Unauthorized External Access to ICS Devices
This rule detects successful network connections from external (internet) IP addresses to common Industrial Control System (ICS) ports, such as Modbus (502) and EtherNet/IP (44818). This activity could indicate unauthorized access attempts, reconnaissance, or exploitation of internet-exposed ICS assets. The rule specifically filters for allowed/accepted/permitted connections and excludes connections from RFC 1918 private IP addresses and a configurable list of authorized external IPs.
Microsoft Sentinel (KQL)
