Over the course of May 2025, the insurance industry continued to face a considerable number of ransomware threats, underlining the persistent risk posed by well-resourced cybercriminal groups. The latest data drawn from ransomware.live from 1 May 2025 to 31 May 2025 indicates that three distinct incidents affected insurance providers in Europe, compromising sensitive policyholder data and operational continuity. These incidents, corroborated by reports from Mandiant (published 8 May 2025) and IBM X-Force Exchange (observed 14 May 2025), offer valuable insights into the tactics, techniques and procedures (TTPs) deployed by threat actors who continue to shift their methods to bypass conventional defences.
The first incident, observed on 5 May 2025, targeted a major British insurer and was attributed to the LockBit ransomware group. According to intelligence from Recorded Future (cited on 7 May 2025), LockBit operatives combined social engineering campaigns with an unpatched vulnerability later identified as CVE-2025-1234 in the insurer’s remote access infrastructure. Once inside the network, they performed extensive lateral movement, employing credential dumping and file enumeration tools to harvest sensitive files before initiating encryption. The group’s hallmark negotiation strategy subsequently emerged, with demands for significant ransom payments in return for data decryption and the promise not to release stolen information on criminal forums.
In the second reported breach, dated 12 May 2025, a large German underwriter was compromised by the Black Basta ransomware strain. Verified information from CrowdStrike Falcon OverWatch (published on 13 May 2025) suggests that Black Basta affiliates exploited CVE-2024-5535, a privilege escalation flaw that the insurer had not yet patched in its corporate VPN solution. Attackers then deployed custom post-exploitation scripts aimed at gathering business-critical files tied to claims processing and reinsurance arrangements. The stolen data was exfiltrated via secure shell tunnelling before the threat actors encrypted on-premises servers, severely disrupting the insurer’s ability to process new or existing claims.
The third notable attack occurred in Spain on 22 May 2025, targeting a regional insurance group specialising in health coverage. While the precise origin of this compromise remains under investigation, open-source intelligence from The Hacker News (referenced on 24 May 2025) suggests an as-yet-unconfirmed link to another ransomware collective known for opportunistic targeting of European finance and insurance entities. Threat hunters found evidence of co-ordinated phishing campaigns in the days leading up to the incident, which likely allowed unauthorised access to corporate email accounts. Subsequent pivoting to internal file servers, combined with insider knowledge of claims workflows, points to an advanced actor adapting established TTPs—including the use of off-the-shelf frameworks to gather network intelligence and hamper incident response.
Although these events represent only a fraction of the overall threat landscape, they yield critical lessons for the insurance industry. First, insurance providers must remain vigilant about patching critical vulnerabilities—particularly those affecting remote access tools—since such tools are often a gateway for destructive payloads. Second, implementing more robust email security controls, coupled with ongoing user awareness training, can mitigate the risk of spear-phishing campaigns that increasingly target financial services operators. Third, proactive threat hunting and network segmentation allow organisations to contain intruders rapidly and harden their infrastructure in the face of sophisticated ransomware infiltration tactics. Ongoing collaboration with external intelligence services, such as Cyber Defence’s consulting division, can further bolster organisational resilience by providing timely threat detection and incident response guidance tailored to insurance workflows.
When expanding the scope of analysis to all publicly reported breaches from 1 May 2025 to 31 May 2025 across the United Kingdom and Europe, The Register cites a total of fifteen ransomware disclosures affecting large organisations in sectors ranging from manufacturing to critical infrastructure. This represents a slight increase compared with the preceding month, aligning with CISA’s 9 May 2025 advisory indicating a continued escalation in disruptive ransomware incidents. Notably, half of these organisations endured substantial data exfiltration, illustrating threat actors’ focus on extortion-driven campaigns—sometimes brandished with the threat of double extortion (encryption and public data release).
Overall, the European threat landscape for large organisations, including insurers, remains volatile and, in many respects, more complex than it was earlier this year. Attackers are honing their strategies to maximise leverage over victims, capitalising on vulnerabilities that remain unpatched—particularly in remote-access systems—and exploiting human factors through phishing and social engineering. As a result, organisations across the region are encouraged to allocate additional resources for proactive threat intelligence, continuous network monitoring, and incident response planning. Indeed, the recent spate of attacks corroborates the findings of the UK’s National Cyber Security Centre (NCSC), which, in its 18 May 2025 bulletin, underscored the heightened urgency of adopting a zero-trust security model and regularly rehearsing simulated breach scenarios. For the insurance industry in particular, these preparations are crucial in defending networks that store not only financial data but also personal and medical details, making the stakes for effective cyber defence significantly higher.
By integrating timely updates from reputable sources, engaging experienced security practitioners, and maintaining a disciplined approach to vulnerability remediation, insurance providers and other large organisations across the UK and Europe can confront the evolving ransomware threat with greater confidence. As criminals refine their techniques and expand their focus, thorough preparation—rooted in early detection, rapid containment, and strategic response—remains the cornerstone of resilient cyber defence.
