Sony Network Communications has disclosed a data breach affecting more than 2.58 million customer records linked to its Japanese internet service provider, So-net, after an unauthorised party accessed its membership database.
The incident also exposed email addresses and passwords belonging to 54,401 accounts across four email services, as well as the bank account details of 16 people and 7 password-reset notification records.
The company disclosed the incident on October 27, after discovering that an external party had accessed its database a few days ago, on October 19. The breach affects both current and former So-net subscribers, as well as customers using plala (S Course), another internet service operated by the company.
How the Sony So-net Data Breach Happened
According to Sony Network Communications, the unauthorised access occurred on October 19, where the company then discovered the intrusion on October 23 and immediately shut down the affected server and blocked communications from the source of the attack.
An investigation conducted the following day confirmed that customer information had been exposed, and the company subsequently reported the incident to Japan’s Personal Information Protection Commission and began investigating its cause.
The breach affected 2,141,986 So-net customer records and another 443,495 records belonging to plala (S Course) subscribers, bringing the combined figure to 2,585,481 records.
However, Sony has not fully disclosed how many unique individuals are affected.
What Information Was Exposed?
The compromised So-net and plala records contained customers’ names, phone numbers, email addresses, user IDs, dates of birth, genders, and internet connection IDs.
The incident also exposed email addresses and their associated passwords for 54,401 accounts across four So-net email services. These include Mail Service (G), A-Box, So-net VAIO Mail, and PostPet Mail Account Service.
Sony also confirmed that 16 records containing bank account information were exposed, including financial institution names, branch details, account numbers, and account holders’ names. But the company said it does not hold customers’ bank account PINs.
Additionally, seven password-reset notification records were exposed.
The company clarified that credit card information was not included in the compromised records, also adding that the passwords used to access customers’ So-net and plala accounts were not exposed.
Sony Resets Exposed Email Passwords
Following the discovery, Sony Network Communications reset the passwords associated with the 54,401 affected email addresses on October 27 to prevent further unauthorised access.
Customers using the affected email services must create new passwords before they can resume using their accounts.
In a further notice published on November 6, the company provided additional information about the affected So-net customers and warned them to be cautious of suspicious emails, text messages, and phone calls.
According to Sony, it had not identified any cases of customer information being misused or secondary damage directly linked to the incident. However, it warned that the exposed information could be used to send fraudulent communications to affected customers.
The company also advised customers against opening suspicious links or attachments and reminded them that it would never request passwords or sensitive personal information through email, SMS, or telephone calls.
Investigation Into the Breach Continues
While Sony Network Communications has not disclosed how the attackers gained access to its membership database or even identified those responsible, its investigation into the cause and full circumstances of the incident remains ongoing.
The company has apologised to affected customers and said it would review its security measures and information management systems to prevent similar incidents.
With more than 2.58 million customer records exposed, the incident raises further concerns about how internet service providers protect the personal information they collect from subscribers.
As such, the findings of Sony’s ongoing investigation will be important in understanding how the intrusion occurred and what additional measures the company and other companies operating in the same industry need to take.
