MalwarePublished 28 Sep 2026

Japan's Keio confirms ransomware attack disrupted business systems

Source Bleeping Computer

ransomware

Description

Keio Corporation, a major Japanese railway and hospitality operator, suffered a ransomware attack that disrupted some business systems, primarily affecting its hospitality operations. The attack was confirmed on September 26, 2026, and led to a network shutdown to prevent further damage. The company is investigating the extent of the impact and whether any customer or partner data was accessed. The ransomware incident impacted payment systems and caused delays in customer-facing services at Keio Plaza Hotel Tokyo. There is no public claim of responsibility by any ransomware group at this time. A separate cyber incident was reported by Tokyo Metro, but no confirmed link between the two events exists.

Impact

The ransomware attack disrupted Keio's hospitality business systems, including payment systems and customer-facing services, causing operational delays. Train operations were reportedly unaffected. There is uncertainty about whether any customer or business partner information was compromised. The incident caused a network shutdown to contain the attack, impacting business continuity in the hospitality segment.

Defensive guidance

Keio Corporation has already taken action by shutting down its network to prevent further damage and is investigating the attack with external experts and law enforcement. No public patch or fix applies as this is a ransomware incident. Organizations should monitor official updates from Keio for further remediation guidance. No additional mitigation recommendations are provided due to lack of specific technical details.

Summary

Keio Corporation experienced a ransomware attack on its group servers, confirmed early on September 26, 2026. The attack disrupted business systems related to its hospitality division, including payment processing and customer services, but did not affect train operations. Keio responded by shutting down its network and is collaborating with external experts and law enforcement to investigate the attack vector and damage. No ransomware group has claimed responsibility publicly. The company is assessing whether sensitive information was accessed. A separate, unrelated cyber incident occurred at Tokyo Metro involving unauthorized access to email addresses.

References

bleepingcomputer.com/news/security/japans-keio-confirms-ransomware-attack-disrupted-business-systems/ (opens in a new tab)

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Description

AI analysisMachine-generated, updated 28 Sep 2026, 21:03 UTC

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