Detection of Internet Accessible Device

ID: DET0796
Domains: ICS
Analytics: AN1928, AN2222, AN2253, AN2256
Version: 1.0
Created: 21 October 2025
Last Modified: 13 October 2026

Analytics

AN1928

Real-time monitoring identifies inbound connections to Industrial Control System (ICS) Windows application servers from internet-routed Internet Protocol (IP) addresses. OT operational-fidelity gate: Alert only when the asset's documented role does not permit the connection and the destination/proxy/service is outside the approved communications profile, with process/service identity used as corroboration where available. Suppress approved vendor support, update repositories, remote operations, failover paths, and documented temporary connectivity.

Log Sources
Data Component Name Channel
Logon Session Metadata (DC0088) WinEventLog:Security Windows Security Event ID 4624/4625: inbound authentication attempt or successful session from internet-sourced Internet Protocol (IP) address to Industrial Control Systems (ICS) application port
Mutable Elements
Field Description
OrganizationalIPSpace Documented internal/organizational IP address ranges.

AN2222

Real-time monitoring identifies Industrial Control System (ICS) field device IPs receiving inbound connections from internet-sourced IP addresses on ICS protocol ports. OT operational-fidelity gate: Alert only when the asset's documented role does not permit the connection and the destination/proxy/service is outside the approved communications profile, with process/service identity used as corroboration where available. Suppress approved vendor support, update repositories, remote operations, failover paths, and documented temporary connectivity.

Log Sources
Data Component Name Channel
Network Traffic Flow (DC0078) NSM:Connections inbound connection to field device Internet Protocol (IP) address from source outside RFC1918/organizational IP space on Industrial Control System (ICS) protocol port
Mutable Elements
Field Description
OrganizationalIPSpace Documented internal/organizational IP address ranges.

AN2253

Real-time monitoring identifies an Industrial Control System (ICS) device or server accepting an inbound connection on its native protocol port from a source Internet Protocol (IP) address outside the organization's address space. Documented in Trend Micro's manufacturing honeypot research, with adversaries exploiting exposed Siemens S7, Omron Factory Interface Network Service (FINS), EtherNet/IP, and misconfigured Virtual Network Computing (VNC). OT operational-fidelity gate: Alert only when the asset's documented role does not permit the connection and the destination/proxy/service is outside the approved communications profile, with process/service identity used as corroboration where available. Suppress approved vendor support, update repositories, remote operations, failover paths, and documented temporary connectivity.

Log Sources
Data Component Name Channel
Network Traffic Flow (DC0078) perimeter:firewall inbound connection to Industrial Control Systems (ICS) device/server Internet Protocol (IP) address on ICS protocol port from source not in organizational IP space
Mutable Elements
Field Description
OrganizationalIPSpace Documented internal/organizational IP address ranges.

AN2256

Real-time monitoring identifies Secure Shell (SSH), web application, or Industrial Control System (ICS) Application Programming Interface (API) authentication attempts on ICS Linux servers from internet-sourced Internet Protocol (IP) addresses. OT operational-fidelity gate: Alert only when the asset's documented role does not permit the connection and the destination/proxy/service is outside the approved communications profile, with process/service identity used as corroboration where available. Suppress approved vendor support, update repositories, remote operations, failover paths, and documented temporary connectivity.

Log Sources
Data Component Name Channel
Logon Session Metadata (DC0088) syslog:auth authentication attempt or success from internet-sourced Internet Protocol (IP) address not in organizational IP space
Mutable Elements
Field Description
OrganizationalIPSpace Documented internal/organizational IP address ranges.