SK Telecom shares plunge after data breach due to cyberattack

SK Telecom shares fell as much as 8.5 per cent on Monday to hit their lowest level since August last year, after South Korea's biggest mobile carrier disclosed it suffered a leak of customer data earlier this month caused by a cyberattack.

The company said in a statement it would take full responsibility for any harm caused as a result of the breach that was detected on April 18. It described the incident as a large-scale leak of data due to malware, without providing more details.

SK Telecom also said it would start offering free universal subscriber identity module (USIM) replacements to all 23 million users for free at more than 2,600 retail stores nationwide from Monday following the cybersecurity breach.

SK Telecom also urged customers to sign up for its USIM Protection Service, which it said provided the same level of prevention as replacing a USIM card.

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About 5.54 million people had signed up for the service, accounting for nearly a quarter of SK Telecom's 23 million subscribers as of Sunday, according to the company.

SK Telecom shares closed down 6.7 per cent, posting the biggest daily drop since March 2020, versus the benchmark KOSPI's 0.1 per cent rise.