{
  "port": 1091,
  "protocol": "tcp",
  "service": "FOUNDATION Fieldbus HSE — System Management",
  "oneLiner": "System management for FOUNDATION Fieldbus HSE: device addressing, tags, and schedule synchronisation.",
  "whatItIs": "System Management is the FOUNDATION Fieldbus service that assigns device addresses and tags, locates devices by tag, and keeps function-block execution schedules synchronised across a segment. The Fieldbus Foundation registered it on 1091 as the third of the HSE ports. It appears on linking devices and gateways from process-automation vendors, and its presence is a strong indicator of an industrial network segment.",
  "exposure": {
    "verdict": "never",
    "note": "This service can address and re-tag field devices. It must stay inside the plant control network, firewalled from IT and unreachable from the internet."
  },
  "checkCommand": "nmap -sV -Pn -p 1091 TARGET",
  "links": [
    {
      "title": "IANA port registry — 1091 (ff-sm)",
      "url": "https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=1091",
      "kind": "iana"
    },
    {
      "title": "ITI/ICS-Security-Tools — ICS protocol port list (FOUNDATION Fieldbus HSE, 1089-1091)",
      "url": "https://github.com/ITI/ICS-Security-Tools/blob/master/protocols/PORTS.md",
      "kind": "github"
    }
  ]
}