Pierluigi Paganini
March 08, 2025
Japanese telecom giant NTT suffered a data breach that exposed information of nearly 18,000 corporate customers.
On February 5th, the security team detected suspicious activity in its ‘Order Information Distribution System,’ and immediately restricted access to device A.
“NTT Communications Corporation (NTT Com) discovered that its facilities had been illegally accessed on February 5, and confirmed on February 6 that some information may have been leaked (hereinafter referred to as the “Incident”).” reads the data breach notification published by the company. “As a result of our internal investigation, we have discovered that some of the information about services for corporate customers stored in our internal system, the Order Information Distribution System *1 , may have been leaked to the outside. Please note that information about services for individual customers was not included.”
The company detected suspicious activity on February 5th, then it restricted access to its systems and launched an investigation that led to the discovery of a data leakage. Further investigation revealed unauthorized access on February 15th, leading to the blocking of another device.
The investigation revealed that the incident exposed the data of 17,891 companies. The company announced that it will notify affected customers.
Potentially exposed information includes contract number, customer name (contract name), name of customer contact, telephone number, email address, address, information related to service use.
The incident did not expose contracts for corporate smartphones and mobile phones provided directly by NTT Docomo.
The company announced it will enhance security measures, improve service quality, and promptly disclose updates while maintaining customer confidentiality.
In May 2020, NTT Communications (NTT Com) disclosed a data breach that impacted hundreds of customers.
The company launched an investigation after discovering unauthorized access to some systems on May 7, 2020, and then this week, it confirmed that threat actors may have been stolen.
“NTT Communications (hereafter NTT Com) detected an unauthorized access to our equipment that has been made by an attacker on May 7, and the possibility that some information may have leaked to the outside was confirmed on May 11.” reads the data breach notification.
Experts at NTT Com initially noticed suspicious activity on an Active Directory server, then they discovered that threat actors have breached an operational server and an information management server that stored customer information. The internal investigation revealed that attackers initially targeted a server in Singapore, then used it for lateral movements and reached the infrastructure in Japan.
In response to the incident, the company shut down impacted servers to prevent the malware from spreading and communicating with external servers.
According to NTT, the security breach could impact 621 companies whose information was stored on the information management server.
The company announced that it has taken additional measures to prevent similar attacks in the future.
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