Maritime Incident Response and SIEM Threat Detection

The Telemetry No One Is Watching

A modern vessel is full of security-relevant signals that, on most ships, no one ever looks at. The bridge network logs traffic between ECDIS, AIS, GPS and the other navigation systems. The satcom and 5G terminals log connections, sessions and configuration changes. The firewalls, where they exist, log allowed and denied connections between zones. The endpoints log logins, application activity and media insertion. Taken together, this telemetry would let a competent analyst spot a developing compromise long before it became an incident. The problem is that on most vessels it is generated and then discarded, because there is no one to watch it and nowhere for it to go.

The crew cannot fill this gap. The master, chief officer and chief engineer are not security analysts, they are fully occupied running the vessel, and they have neither the tooling nor the time to correlate log streams across a dozen systems in real time. Asking them to monitor security telemetry alongside their existing duties is unrealistic and would not produce reliable detection even if attempted. The detection capability has to live somewhere that can actually exercise it, which in practice means a shore-based security operations capability fed by the vessel's signals.

This is the gap a maritime SIEM is built to close. By collecting the security telemetry the vessel already generates, filtering and prioritising it on board, and forwarding what matters to a shore SOC, the SIEM turns a fleet of vessels operating blind into a monitored estate where a developing problem on any ship can be seen and acted on. It does not add work for the crew; it gives the shore organisation visibility the crew was never positioned to provide.

Maritime SIEM Architecture

A maritime SIEM is architecturally different from an enterprise one because of the link between the data source and the analysis. In an enterprise, endpoints and servers stream logs continuously to a central SIEM over abundant bandwidth. A vessel cannot do this: the satcom or 5G link is too narrow, too intermittent or too expensive to forward raw logs continuously. The architecture therefore has to do meaningful work on board before anything crosses the link.

The on-board component, often a lightweight collector or edge appliance, gathers telemetry from the bridge network, the satcom terminals, the firewalls and the endpoints. It normalises and filters that telemetry locally, applies a first layer of detection logic, and buffers data so nothing is lost when the link is down. Critically, it prioritises: high-value security events and alerts are forwarded promptly, while bulk low-value telemetry is summarised, sampled or held on board for retrieval only when needed. This on-board triage is what makes maritime monitoring feasible within the bandwidth budget.

The shore component receives the forwarded events, correlates them across the fleet, applies deeper analytics that the on-board appliance cannot, and presents them to the SOC analysts who triage and escalate. The shore side also holds the historical baseline that makes anomaly detection possible: knowing what normal looks like for a given vessel class lets the system flag the abnormal. The two halves work together, with the on-board appliance acting as the eyes and a smart filter, and the shore SOC acting as the brain and the responder.

• On-board collector: gathers bridge, satcom, firewall and endpoint telemetry, normalises and buffers it locally
• On-board triage: applies first-layer detection and prioritisation so only what matters crosses the link
• Resilient forwarding: buffers during link outages, forwards high-value events promptly, summarises the rest
• Shore correlation: cross-fleet analytics, historical baselines and deeper detection the appliance cannot run
• Shore SOC: analyst triage, escalation and coordination with the vessel and the incident response team

Tuning Detection for the Maritime Environment

An enterprise SIEM tuned for office threats will miss most of what matters at sea and drown the analysts in irrelevant alerts. Maritime detection has to be tuned for the signals and scenarios specific to the vessel environment, which look quite different from a corporate network. The detection content is where a generic SIEM becomes a maritime SIEM.

High-value maritime detections include satcom anomalies, such as a terminal making outbound connections to unexpected destinations or a configuration change outside a maintenance window, which can indicate a compromised satcom unit. They include navigation-source irregularities, such as AIS data inconsistent with radar and GPS, or GNSS position jumps consistent with spoofing, which can indicate either an attack or an environmental spoofing event the bridge needs to know about. They include USB and removable-media events on OT hosts, which on an isolated vessel are a leading infection indicator. And they include cross-zone traffic, such as a connection from the crew network toward bridge OT or from any endpoint toward the satcom management interface, which almost always indicates a segmentation failure or an attacker pivoting.

Tuning is iterative. The first weeks of a maritime SIEM deployment are spent learning the normal behaviour of each vessel class, suppressing the benign patterns that would otherwise generate noise, and sharpening the detections that catch the scenarios that matter. The goal is a manageable stream of high-fidelity alerts that a shore analyst can actually triage, not a firehose that trains the SOC to ignore it. Detection content is also kept current as the threat picture evolves and as new equipment and connectivity, such as 5G links, change what normal looks like.

Where SIEM Meets Incident Response

Detection is only valuable if it feeds a response, and maritime incident response operates under constraints that reshape every assumption an enterprise plan makes. The satcom link is intermittent and expensive. The vessel cannot be physically reached for days or weeks. The crew on board may be the only team able to execute manual containment, and they are not full-time security responders. A maritime SIEM that detects a problem must therefore hand off into a response plan designed for these realities, or the detection achieves nothing.

The handoff has two directions. When the shore SOC detects something on the telemetry that the crew has not noticed, it must be able to reach the vessel through a defined channel, communicate clearly using a structured format that survives a noisy link, and give the master executable guidance for the first hour without assuming a perfect connection. When the crew notices something first, such as an ECDIS showing an impossible position, the plan tells them what immediate action to take and how to notify shore, while the SIEM provides the shore team with the telemetry context to understand what is happening.

Incident classification ties the two together. The maritime severity model, classifying incidents as Safety-Impacting, Operations-Impacting or IT-Only, lets the SOC and the crew speak the same language about urgency. A SIEM detection that touches a safety-relevant system becomes a Tier 1 incident, triggering immediate shore notification and the master's authority to take protective action such as reverting ECDIS to paper charts or isolating a suspect system. The same telemetry that detected the problem also supports the response and, afterwards, the post-incident review and the evidence pack.

Staffing the Maritime SOC

A maritime SIEM needs people behind it, and shipowners choose from a few models depending on fleet size and maturity. The smallest operators often cannot justify a dedicated maritime SOC and instead use a managed service, where a provider runs the monitoring and triage on their behalf and escalates genuine incidents to the shipowner's designated person ashore and crisis team. This is the fastest route to coverage and removes the need to recruit scarce maritime-aware analysts.

Larger fleets may build an in-house or hybrid SOC, where the shipowner's own team handles triage and the harder analysis or out-of-hours coverage is supplemented by a provider. Whatever the model, the analysts need maritime context: an analyst who does not understand that an AIS-radar discrepancy or a satcom configuration change has operational meaning will mis-triage the very alerts that matter most. This is why a maritime SOC is not simply an enterprise SOC pointed at vessel logs; the people, the detection content and the response runbooks all need maritime knowledge.

Codesecure designs maritime SIEM and SOC capabilities suited to the shipowner's fleet size and maturity, covering the on-board collection architecture, the detection content tuned for vessel and port environments, the integration with the incident response plan, and the choice of staffing model. The design produces the Detect and Respond evidence that IMO 2021 expects, and integrates with the risk assessment and the Safety Management System so the monitoring is part of a coherent programme rather than a standalone tool.

Detection, Response and IMO 2021

Monitoring and incident response are not optional extras under the IMO framework; they are explicit functions. MSC-FAL.1/Circ.3 names Detect and Respond among the five functional elements the Safety Management System must address, and the BIMCO Guidelines treat detection and response as core control areas. A shipowner who can identify and protect assets but cannot detect a developing incident or respond to one has an incomplete programme, and an auditor will see the gap.

What an auditor looks for is evidence that the company can actually detect and respond, not merely that it intends to. For detection, that means monitoring is in place across vessel and shore systems, with anomaly detection and log review, and that the monitoring produces records. For response, it means a documented incident response plan, defined vessel-to-shore communication protocols, clear recovery decision authority, and evidence that the plan has been exercised through drills and tabletops. A maritime SIEM feeding a shore SOC, paired with a tested incident response plan, is the most direct way to satisfy both functions with real capability rather than paper.

Codesecure delivers the full chain: the maritime risk assessment that prioritises what to monitor, the SIEM and SOC design that provides detection, the incident response plan built for the constraints of the sea, and the drills that prove it works. The result is a coherent Detect-and-Respond capability that satisfies IMO 2021, supports BIMCO gap closure, answers the charterer security questionnaire and, most importantly, gives the shipowner genuine early warning of cyber problems across the fleet.