Over 67,000 users suffer personal data leak: South Korean banking sector sounds alarm over wave of AI attacks
The South Korean financial sector faced a massive cybersecurity shock in early October 2026. This time, cybercriminals did not rely on traditional manual methods, but weaponized Artificial Intelligence (AI) to breach systems, leading to the leak of personal data belonging to over 67,000 users. The incident forced national authorities to intervene immediately to prevent a wider crisis.
Fatal weaknesses in auxiliary systems
Investigating authorities determined that the attacks were highly sophisticated, carrying signatures of an automated AI tool originating from China. Notably, the hackers made no attempt to breach the "core system" – where the most critical databases reside under strict, multi-layered security.
Instead, they directed their attacks at external servers and websites used daily by bank staff for routine operations. Lee Eog Weon, Chairman of the Financial Services Commission (FSC), noted that these auxiliary systems often receive less management oversight. This negligence created invisible loopholes. The hackers' AI tools rapidly scanned, exploited vulnerabilities, and successfully penetrated the network, bypassing internal security barriers.
Widespread damage: Tens of thousands of users' personal data leaked
Driven by AI's automated intrusion speed, the extent of the damage quickly escalated. Within days, several major names in South Korea's financial sector—including Shinhan, KB Kookmin, Hana, Woori, NH Nonghyup, BNK Busan, Welcome Savings, and Hyundai Capital—were targeted.
Among them, Yegaram Savings Bank suffered the heaviest hit, with approximately 40,000 customers having information exposed, such as full names, dates of birth, and contact details. Shinhan Bank ranked second, with 25,000 loan application records stolen. The leaked data was highly sensitive, including phone numbers, annual incomes, and credit limits. At other institutions like BNK Busan, even contract employees' details were compromised.
In total, the number of victims in this emergency data leak surpassed 67,000, sparking significant concern among both the public and corporate clients using services at these banks.
Red alert issued: Strategy to deploy AI for defense
In response to the rapidly escalating cyber threat, South Korea raised its alert status to the highest level. On October 4, South Korean President Lee Jae Myung personally ordered a comprehensive investigation and swift, definitive remedies.
That same day, the FSC convened an emergency meeting with financial industry associations and executives from the affected institutions. The regulatory body immediately ordered a comprehensive audit of bank IT systems and demanded tighter external access controls. Crucially, as traditional security technologies show signs of falling behind against AI-driven attacks, the FSC issued an urgent directive: the financial sector must immediately build defense systems that use AI to fight AI. Any institution found negligent or failing in its security responsibilities will face severe penalties.
This record-setting user personal data leak in South Korea serves as a stark warning. It demonstrates that cybercrime has entered a new era powered by AI. For businesses, financial institutions, and the general public, continuously upgrading security systems and remaining vigilant over personal data has never been more urgent.
Reference: Reuters - South Korean president orders probe into data leaks across financial industry
