Seoul: Personal information and universal subscriber identity module (USIM) data of all subscribers of SK Telecom Co., South Korea's leading mobile carrier, have been leaked in a large-scale cyberattack detected last month, a government-private investigation team revealed Monday.
According to Yonhap News Agency, the interim findings indicate that the breach dates back to June 15, 2022. Unidentified perpetrators are believed to have planted malware on the company's servers, compromising a total of 23 SK Telecom servers that store four types of USIM data, including international mobile subscriber identity (IMSI) information.
Among the compromised servers, two were used as temporary storage for personal data, such as names, birthdates, phone numbers, and email addresses. Investigators are still working to determine the exact scope of data stored on those two servers.
SK Telecom detected the breach on April 18, raising concerns about the security of personal and sensitive information of millions of its subscribers, as the investigation continues to uncover the full extent of the data compromise.