Resonac Holdings faces ransomware attack, restoring operations

Resonac Holdings Corporation (TSE:4004) is recovering from a cyberattack involving ransomware that initially impacted its systems on May 20, 2025. The company detected unauthorized modifications to files on some servers and PCs within the company and group companies. In response, the company established an emergency response headquarters and implemented network isolation measures, which led to partial system unavailability and disruptions in business operations. As of June 3, 2025, Resonac is continuing restoration efforts for the remaining PCs, systems, networks, and infrastructure to normalize operations. The company has begun gradually resuming operations for certain businesses where safety has been confirmed since May 23. According to external specialists, there has been no confirmation of information leaks involving the group or its business partners, and production and shipment of products have also been gradually resuming. The company has reported the incident to law enforcement. To prevent recurrence, Resonac Holdings will implement comprehensive countermeasures, including virus scans, password resets, early detection tools, reinforced monitoring, and enhanced employee training. The company is assessing the potential impact on its business performance and will make a prompt disclosure if a significant effect is determined.