In a significant cybersecurity breach, hackers have accessed personal information belonging to current and former subscribers of So-net and Plala, internet services under Sony Network Communications in Japan. The company revealed on October 27 that nearly 2.6 million records were compromised in the attack.
Details of the Security Breach
The intrusion was initially detected on October 23, four days after the attackers infiltrated the So-net member database on October 19. Upon discovery, the company promptly disconnected the targeted server to halt further unauthorized access. By October 24, investigators had verified the theft of personal data and assessed the breach’s extent.
The information obtained in the breach includes sensitive details such as names, birth dates, gender, phone numbers, email addresses, user IDs, and internet connection IDs. The majority of the affected records, approximately 2.14 million, belong to So-net subscribers, whereas 443,000 pertain to Plala (S Course) users. Of these, around 293,000 relate to individuals who discontinued the services in March 2026 or later, as their data is retained temporarily to manage billing and support inquiries.
Further Implications of the Data Leak
In addition to subscriber data, the attackers also compromised about 54,000 email addresses and their passwords across four other mail services, including Mail Service (G), A-Box, So-net VAIO Mail, and the PostPet email account service. However, no password breaches were reported for the basic free mailbox provided with subscriptions.
In response, So-net initiated a password reset for all affected email accounts on October 27, requiring users to update their passwords to regain access. This measure aims to prevent potential misuse of the compromised email credentials, as stated in a translated FAQ document issued by the company.
Ongoing Investigation and Security Measures
The breach also affected 16 records containing banking details, such as bank and branch information, account type, account number, and account holder’s name. Nevertheless, So-net assured that it does not store PINs, thereby mitigating further risk. Importantly, no credit card information was compromised, as such data is not stored by the company.
The exact method of the breach remains undisclosed, with So-net attributing it to unauthorized third-party access. The company continues to investigate the incident and has reported it to Japan’s Personal Information Protection Commission. Meanwhile, Sony’s other services, including NURO, remain unaffected.
As investigations proceed, the importance of robust cybersecurity measures grows ever more critical in safeguarding sensitive data against increasingly sophisticated cyber threats.
