nikkeibp.co.jp Domain Breach Exposure Report

The domain nikkeibp.co.jp has experienced a high volume of data breaches and infostealer activity over the past year, with a significant portion of events originating from "Combolist sources." The timeline indicates a surge in client-related data breaches starting in March 2026, alongside a notable increase in employee-related breaches in September 2025 and January 2026. Malware families such as LummaC2, Rhadamanthys, and Redline are prevalent, suggesting active credential harvesting and data exfiltration campaigns targeting the organization's clients and employees. This exposure presents a critical risk due to the sheer volume of historical data breaches and ongoing infostealer activity, impacting over 6,000 clients and 1,000 employees. The prevalence of credential stuffing and data dumps indicates a high likelihood of compromised credentials being used in further attacks. Remediation should focus on strengthening authentication mechanisms, particularly for client-facing services like signon.nikkeibp.co.jp and medical.nikkeibp.co.jp, implementing robust endpoint security to detect and block infostealer malware, and conducting thorough investigations into the identified data breaches to understand the scope of compromised data and affected individuals.