A malware infection on an employee’s personal computer led to unauthorized access to Nikkei Inc.’s internal Slack workspace, exposing private data and chat histories of over 17,000 individuals.
What Happened
Nikkei Inc., the Japanese media giant that owns the Financial Times and lends its name to the Nikkei 225 stock index, discovered a significant security breach in September. Attackers used compromised login credentials stolen from an employee’s malware-infected personal device to access the company’s internal Slack workspace.
This wasn’t a brute-force attack. It was attackers using legitimate credentials, slipping through the door undetected.
What Was Exposed
The breach affected 17,368 employees and business partners, exposing:
- Names and email addresses
- Extensive chat histories from the Slack workspace
Chat histories are particularly concerning. They can contain proprietary business information, strategic plans, sensitive client discussions, intellectual property details, or security practices that attackers can exploit.
This type of data is gold for cybercriminals. It’s used for targeted phishing campaigns, business email compromise scams, or as leverage in ransomware attacks—a tactic called “double extortion” where attackers threaten to leak stolen data if ransom isn’t paid.
How It Started: The Personal Device Problem
The breach highlights a persistent cybersecurity challenge: the blurring line between personal and professional digital environments. Malware on personal devices often includes info-stealers, keyloggers, or trojans designed to harvest login credentials for corporate platforms.
Once attackers have these credentials, they bypass many security defenses by masquerading as legitimate users. For a company like Nikkei, deeply embedded in global finance and information, this access provides an insider view into operations, strategies, and vulnerabilities.
Nikkei’s Response
Upon discovery, Nikkei acted swiftly:
- Implemented password resets for all affected accounts
- Deployed containment measures to prevent further unauthorized access
- Voluntarily informed Japan’s Personal Information Protection Commission
In an official statement, the company reassured stakeholders: “No leakage of information related to sources or reporting activities has been confirmed. We take this incident seriously and will further strengthen personal information management to prevent any recurrence.”
The Bigger Lesson
This breach is a stark reminder that even formidable institutions are only as strong as their weakest link. When employees use personal devices for work-related logins—or reuse passwords across personal and professional accounts—they create entry points for attackers.
For a media organization like Nikkei, the potential damage extends beyond data loss. Public exposure of internal communications can undermine trust among readers and partners. And in today’s threat landscape, stolen credentials from one employee’s compromised personal device can unlock an entire organization’s most sensitive conversations.
The lesson? Corporate security isn’t just an IT problem, it’s a human one.
