monex.co.jp Domain Breach Exposure Report

The telemetry indicates a significant exposure of client data, with 9418 historical data breaches and 1914 active infostealer logs observed between July 2025 and June 2026. The majority of these events are linked to "Combolist sources" (99.5%), suggesting credential stuffing attacks or compromised credential reuse. The affected services primarily include login portals for "monex.co.jp" and its subdomains, indicating a direct impact on customer access and potentially financial transactions. The timeline shows a surge in client-related events in March and April 2026, coinciding with a rise in employee-related exposures. The high volume of data breaches and infostealer activity, coupled with the targeting of customer-facing login services, presents a critical risk. The prevalence of "Vidar," "LummaC2," and "Rhadamanthys" malware families, known for credential theft and data exfiltration, further elevates the threat. Prioritization should focus on immediate credential reset campaigns for affected clients, enhanced monitoring of login activity for anomalies, and a thorough review of authentication and data protection mechanisms to prevent future compromise.