Acting President Han Duck-soo on Sunday instructed the government to check the adequacy of SK Telecom Co.'s response measures for a potential major leak of universal subscriber identity module data.

A notice reading "SIM card out of stock" is displayed at an SK Telecom store in Seoul on Sunday. (Yonhap)
A notice reading "SIM card out of stock" is displayed at an SK Telecom store in Seoul on Sunday. (Yonhap)

On April 18, SK Telecom detected signs of a massive leak of customers' USIM data due to a cyberattack, prompting the company to announce Friday that it would replace the USIMs of all of its 23 million users.

Han instructed the Ministry of Science and ICT to "closely" inspect the company's response measures, which also include recommending users to sign up for a USIM protection service, according to his office.

He also called on the government to "thoroughly" analyze the cause of the incident while instructing the National Intelligence Service and other relevant agencies to inspect the country's data protection system against cyberattacks, it said. (Yonhap)