South Korean telco giant SK Telecom had its systems hacked recently and the company’s investigation determined that customer data has been leaked.
SK Telecom is South Korea’s largest wireless carrier — it has tens of millions of subscribers and holds roughly half of the local market.
The company revealed on Tuesday in a Korean-language statement posted on its website that it detected an intrusion on April 19. An investigation showed that the attackers deployed malware and managed to obtain personal information belonging to customers.
Following the incident, SK Telecom is offering customers a free SIM protection service designed to prevent SIM swapping, which suggests that the leaked data could be leveraged for such activities.
The company said it immediately deleted the malware deployed by the hackers and isolated compromised systems.
The investigation into the incident is ongoing and the Korea Internet Security Agency (KISA) has been notified.
It’s unclear if SK Telecom was targeted in a ransomware attack. No known ransomware group has taken credit for the hack at the time of writing.
Telecom companies are also often targeted by state-sponsored threat actors specializing in cyberespionage. China is believed to be behind many such attacks against companies in the US and elsewhere.
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