mixi.jp Domain Breach Exposure Report

The telemetry indicates a significant exposure event impacting approximately 50,497 clients and 209 employees, primarily associated with the domain mixi.jp. The exposure is heavily weighted towards historical data breaches (80.7%) and active infostealer logs (19.3%), totaling over 50,000 events. The timeline shows a surge in client-related events in March 2026 and April 2026, with employee-related events peaking in January 2026 and February 2026. The primary malware families observed are LummaC2, Vidar, and Rhadamanthys, all known for credential theft and data exfiltration. The data suggests a high likelihood of compromised credentials and sensitive information being exfiltrated, with a substantial portion originating from "Combolist sources" within leak repositories. Given the high risk score of 95 and the prevalence of infostealer activity and data breaches, this incident requires immediate attention. The focus should be on identifying the root cause of the data breaches and infostealer infections, particularly concerning the LummaC2 and Vidar malware families, and assessing the extent of client and employee data compromise. Remediation efforts should prioritize credential reset for affected users, enhanced endpoint security to detect and prevent infostealer activity, and a thorough review of access controls and data handling policies to prevent future occurrences. The targeted services are primarily related to the mixi.jp domain, suggesting a direct impact on the platform's users and potentially its internal systems.