Japanese e-commerce giant Askul Corporation confirmed that a ransomware attack carried out by the RansomHouse group led to the theft of about 740,000 customer records in October 2025. Askul, which is a major supplier of office supplies and logistics services owned by Yahoo! Japan, suffered a critical failure within their IT system due to the breach, forcing the company to shut down shipments to customers, including the popular retail chain Muji.
Compromised data includes approximately 590,000 business customer service records, 132,000 individual customer records, 15,000 records of business partners (outsourcers, agents, suppliers), and about 2,700 records of executives and employees across group companies.
Detailed information about the breach is not being disclosed by Askul to avoid further exploitation. The company is trying to individually contact affected customers and partners. It has reported the incident to Japan's Personal Information Protection Commission and put in place long-term monitoring to mitigate the risk of misuse.
The RansomHouse group is known to conduct both data exfiltration and encryption operations, and it announced the breach on October 30, followed by two data leaks on November 10 and December 2. An Askul investigation found that the breach occurred due to compromised authentication credentials related to an outsourced partner administrator account that did not have multi-factor authentication (MFA). After accessing the systems, the attackers performed reconnaissance, gathered authentication information, disabled EDR software, and moved laterally between servers to gain privileged access.
Several types of ransomware were deployed; some were even capable of bypassing the EDR signatures of the time. This resulted in widespread data encryption and systemic outages. Another step the attackers took was to clear the backup files to further impede recovery. Askul severed connectivity to infected networks, isolated affected systems, updated EDR signatures, and implemented MFA for all critical systems.
As of mid-December, Askul continues to face disruptions in order shipping and is working to fully restore its systems. The financial impact of the attack has not yet been estimated, and the company has postponed its scheduled earnings report to allow for a thorough assessment.