Cyber Crime
Japanese Telecom Giant NTT Suffers Data Breach, Impacting 18,000 Companies
Japanese telecom giant NTT Communications Corporation (NTT) has issued a warning to nearly 18,000 corporate customers after a cyberattack compromised sensitive customer data. The breach, discovered in early February 2025, targeted the company’s Order Information Distribution System, which stored contract details of 17,891 corporate clients.
Details of the Breach
NTT detected unauthorized access to its systems on February 5 and confirmed potential data leakage by February 6. The breached database contained:
- Customer name (registered contract name)
- Representative’s name
- Contract number
- Phone number
- Email address
- Physical address
- Service usage information
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Notably, contracts for corporate smartphones and mobile services provided by NTT Docomo were unaffected.
Response and Containment
NTT blocked the hacker’s access by February 6. However, on February 15, investigators discovered that the attackers had moved to another network device. This secondary breach was swiftly contained by disconnecting the compromised device, and NTT now believes the threat is fully neutralized.
Unlike many companies that issue personalized alerts, NTT has chosen not to notify affected customers individually, instead opting for a public announcement on its website as the only notification.
NTT’s History of Cybersecurity Issues
This is not the first major cyber incident at NTT. On January 2, 2025, a massive 12-hour DDoS attack disrupted the company’s mobile services and payment platforms. Additionally, in May 2020, hackers infiltrated NTT’s internal network, stealing sensitive data from hundreds of customers.
As one of Japan’s largest telecommunications providers, NTT remains a prime target for cybercriminals. The company is now working to enhance security measures and prevent further breaches in its corporate infrastructure.