Due to the aftermath of a USIM (Universal Subscriber Identity Module) information hacking incident, the number of subscribers moving from SK Telecom to other telecommunications companies has significantly increased. SK Telecom is now expediting the process of replacing USIMs. According to the telecommunications industry on the 20th, there were 11,498 subscribers who moved from SKT to other carriers such as KT and LG Uplus on the 19th. This surge is attributed to the announcement made by a joint public-private investigation team revealing the results of their probe into the hacking incident. The team disclosed that 26,957,749 pieces of USIM information, based on International Mobile Subscriber Identity (IMSI) numbers, were leaked and that servers storing sensitive data like International Mobile Equipment Identity (IMEI) numbers and personal information were attacked.
After the hacking incident, the number of defectors from SKT peaked at 38,716 on the 1st and then declined to below 10,000, but it has once again increased to over 10,000 on the said day. Lim Bong-ho, head of SKT’s MNO (Mobile Network Operator) division, explained, “Although the number of departing customers has decreased compared to the initial impact of the hacking incident, the numbers are still significant compared to usual.”
SKT is hastening the USIM replacement process, swapping out 330,000 USIMs in a single day on the 19th. Considering that the average USIM replacement rate was around 100,000 per day over the past week, this is a substantial increase. As of midnight on the 20th, the cumulative number of USIM replacements due to the SKT hacking incident is 2.52 million, which is roughly 10% of all subscribers. Kim Hee-seop, head of SKT’s PR Center, mentioned during the daily briefing that “with USIM supplies coming in and support from employees on the ground, the number of replacements is rapidly increasing.”
Regarding growing subscriber concerns over potential cloned phone crimes due to IMEI leaks, SKT stated that they have further strengthened security measures. They have enhanced the FDS (Fraud Detection System) to effectively block not only cloned USIMs but also cloned devices, and have prepared various security options including physical USIM replacement, USIM resetting, and eSIM replacement.
From the previous day, SKT has commenced an ‘on-site USIM replacement and resetting service,’ conducting 1,270 USIM replacements mainly for the elderly in five regions: Chuncheon, Changnyeong, Tongyeong, Sinan, and Taean. The company plans to visit 100 cities and counties with limited access to agents by the end of June.
The company stated, “We have not yet confirmed any damage related to the hacking incident and will take full responsibility if any damage occurs.” On the same day, SKT admitted to insufficient security management after failing to detect malicious codes for three years. Ryu Jung-hwan, head of the Infrastructure Network Center, said, “We are looking into the inability to detect the web shell, which initially breached our security, and acknowledge that there were shortcomings despite our belief that a security framework was in place.”