Yoido Full Gospel Church in Seoul said personal data linked to as many as 850,000 members may have been compromised, in a suspected cyberattack whose records appear to reference artificial-intelligence tools.
What the church says was exposed
The church, once recognized by Guinness as the world’s largest congregation, said its initial review identified members’ names and dates of birth. The affected material also included logs showing changes made to personal records.
Those logs covered 2,629 changes to resident registration numbers, 3,964 changes to phone numbers and 7,202 changes to addresses. The church said it was notified of the suspected breach by South Korea’s internet security agency, KISA, on Tuesday afternoon.
Yoido has blocked external access to its systems and changed server passwords. It also plans to notify the 850,000 members whose information may have been affected. The church said it intends to replace its firewall—technology designed to filter unwanted network traffic—and hire security companies to search for additional weaknesses.
Investigators examine possible AI involvement
Cybersecurity firm Oasis Security found the data on an overseas server while tracing internet addresses associated with suspected attacks in September. The server also contained attack logs and account information connected to Yoido and Sarang Church, another large Seoul congregation.
Oasis said the records referred to AI sub-agents. These are helper programs that an AI system can launch to perform separate parts of a task. The attack logs were also described as unusually long and apparently machine-generated.
That evidence does not establish exactly how artificial intelligence was used, however. The churches are still investigating how the attackers gained access, and Oasis said the role of AI remains uncertain.
Sarang Church reportedly lost data relating to about 89,000 members and 286 employees, including its senior pastor. The records suggest that the theft occurred in August. Sarang has created an emergency task force and reported the incident to authorities.
Wider South Korean cyberattacks
The church incidents come as South Korean officials investigate suspected AI-assisted attacks against financial institutions. President Lee Jae Myung said Tuesday that AI is believed to have been used in recent hacks targeting commercial banks.
Shinhan Bank’s breach exposed names, phone numbers, annual income and borrowing limits for about 25,000 customers, according to local news reports. The financial regulator has begun an emergency on-site inspection.
According to Decrypt, the combination of the church investigations and the banking probes has drawn attention to the possibility that attackers are using automated software to handle multiple stages of cyber intrusions. In the church cases, authorities and security researchers have not yet determined whether AI was central to the attacks or simply appeared in related logs.
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