Bithumb Security Breach Leaves Customer Data Under Review

Bithumb has confirmed that unauthorized access to its internal mobile groupware system caused a personal data leak. The exchange discovered the breach, noting that it is still investigating whether the exposed information includes customer records.

The incident emerged alongside cyber intrusions at Mirae Asset Global Investments and Daishin Securities. South Korea’s Financial Supervisory Service is assessing the breaches and the extent of the damage at the affected institutions.

February Error Exposed Control Weaknesses

The incident follows an internal control failure at Bithumb earlier this year. In February, the exchange mistakenly credited customers with 620,000 Bitcoin, worth more than $40 billion, instead of 620,000 won.

Bithumb recovered 99.7% of the accidental credits after restricting trading and withdrawals for affected customers. CEO Lee Jae-won acknowledged weaknesses in the exchange’s internal systems following the error. He said Bithumb was “acutely aware of the deficiency in internal system control.”

Customer Data Exposure Under Review

Bithumb is looking into the scope of the leak after an external party accessed its internal system without authorization. Its review includes determining whether the compromised data included information about exchange members.

Daishin Securities has reported a specific customer impact. In a press release issued on the morning of October 28, the company said personal and credit information belonging to 38,490 customers had leaked. These disclosures followed a hacking incident at Mirae Asset Life Insurance on October 26.

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Regulator Urges Boards to Strengthen IT Security

The investigations coincided with a renewed appeal from FSS Governor Lee Chan-jin for stronger technology security across the financial sector. Speaking on October 28 at a regular meeting with board chairmen from eight bank holding companies, Lee referred to a hacking incident at a major investment firm the previous day.

He warned that artificial intelligence could help attackers detect security weaknesses more easily and make simultaneous attacks more common. His remarks focused on the security challenges facing financial institutions as AI becomes a tool for hacking.

Lee described IT security as a core function for protecting customers’ assets and personal information while preserving financial trust. He urged boards of directors to lead efforts to improve their institutions’ IT security capabilities.

Account Security and Phishing Precautions

Bithumb’s published security guidance advises customers to verify account warnings through the official app or website and avoid links in suspicious emails, texts, or messaging apps. The exchange has previously warned about impersonators using supposed security updates to obtain personal information.

The exchange recommends enabling additional authentication through account security settings. App-based one-time passwords avoid the SIM-swapping risks associated with SMS codes, although they remain vulnerable to phishing.

Its guidance also recommends replacing reused passwords with a unique password that is not shared with email accounts or other services. Bithumb says it does not request passwords, verification codes, or wallet information through messages.

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Related: South Korean Court Halts Bithumb Suspension Following a Legal Battle