As the International Union of Marine Insurance‘s (IUMI) annual conference began in Rotterdam the spectre of malicious cyber-attacks on merchant vessels is causing real concern for the industry.

While the impact of increasing geopolitical risks was the main topic for the opening day the talk in the halls was of the news that a crude oil tanker bound for the US reportedly suffered a cyber incident while transiting the Strait of Gibraltar in early August, with a second vessel also boarded by US Coastguard and the FBI amid fears it too had been targeted.

The VL Prosperity, a Liberian-flagged crude tanker that left Egypt on 1 August 1 enroute to Galveston, Texas. According to Iran’s Mehr News Agency alleged cyber-attack occurred as the tanker passed through the Strait of Gibraltar. It added the intrusion reached the engine room, with hackers slowing coolant flow, raising engine speed and interfering with fuel delivery.

The hackers also allegedly accessed navigation and cargo systems and cut off the ship’s communications for roughly 30 hours.

The vessel was subsequently boarded by a US multi-agency cyber team in the Gulf of Mexico on 21 August to assess its IT and operational technology (OT) systems, with a second tanker boarded on 24 August following another reported compromise.

Malicious cyber activity was reportedly identified, although the vessel remained safe to navigate. Technical detail remains limited, and neither the reported operational impact nor attribution has been independently verified.

Incidents affecting vessels – rather than ports or administrative IT networks – are still rarely reported. But the wider picture is worth watching: the US Coast Guard’s Cyber Protection Team has reportedly undertaken 40 – 50 missions over the past year, while US agencies are reported to be tracking cyber activity affecting nearly 20 vessels globally.

The reports of the attacks came days after the US Coast Guard announced a dedicated Office of Maritime Cybersecurity Policy, which will serve as its central authority for developing and implementing policies governing the cyber safety and security of the marine transportation system.

Marine reinsurance brokers have been quick to highlight the risks and underwriters said they recognised this could be the start of a new era of cyber threat for the maritime sector

“The important point is not to overstate what we know about this individual incident. Technical detail remains limited and some of the reported effects have not been verified. What is notable is that the alleged activity reached beyond administrative IT to the vessel itself. As ships become more connected – and reporting requirements improve – we should expect greater visibility of cyber activity affecting maritime operations,” Harriet Gruen, Head of Cyber Threat Intelligence, Howden Re said.

For the (re)insurance market, the immediate cyber insurance impact appears limited. The longer-term issue is connectivity. As vessels become increasingly networked, the potential interaction between cyber threats, OT, marine risk and geopolitical tensions becomes harder to separate. New US maritime cybersecurity requirements, introduced in 2025 and being phased in through 2027, should also increase visibility of incidents that might previously have gone unreported.

Underwriters in Rotterdam for the IUMI event say the attacks have yet to hit the market’s radar but remain increasingly concerned.

“This is not a systemic risk,” one leading London market figure told Emerging Risks. “Vessels are self-contained and as such they are individual targets. For those who are seeking to assume control of the vessel the threat would likely be to forcibly ground or destroy vessel close to a harbour to cause maximum disruption. This is new and we will need to monitor it.

“The choice is to cover the threat of exclude it, but the problem is if you exclude it are you then starting to exclude risks which have always been covered such as hull damage or grounding. It is a new challenge for the market.

“Marine risk has always reflected the interaction between technology, trade and geopolitics. Greater connectivity adds another layer: a cyber event affecting a vessel’s operational systems has the potential to move quickly from a digital issue to a physical and commercial one. Even where the immediate insured impact is limited, understanding those dependencies will become increasingly important for insurers and reinsurers,” added Richard Miller, managing director, Global Specialty Treaty, at Howden Re said.

The reports of the attacks came days after the US Coast Guard announced a dedicated Office of Maritime Cybersecurity Policy, which will serve as its central authority for developing and implementing policies governing the cyber safety and security of the marine transportation system.