Nikkei, a major Japanese media corporation, reported a data breach affecting over 17,000 individuals tied to its Slack messaging platform. The breach occurred when an employee's computer was infected with malware, leading to stolen authentication credentials that allowed attackers access to Slack accounts. Nikkei identified the security issue in September and quickly implemented measures, including requiring password changes for affected users. The exposed information includes names, email addresses, and chat histories of 17,368 people. Although the data does not fall under Japan's Personal Information Protection Law, Nikkei chose to inform the country's Personal Information Protection Commission to maintain transparency. Importantly, the company stated that no confidential sources or journalistic data were compromised during the breach. Nikkei's security issues are not new. In May 2022, its Singapore subsidiary faced a ransomware attack affecting customer data. Additionally, a 2019 business email compromise attack resulted in a loss of approximately $29 million due to a scam targeting a Nikkei America employee. The company is now focusing on enhancing its personal information management to prevent future incidents.