Bithumb has materially expanded its disclosure of the 27 October intrusion into its internal mobile groupware system. The South Korean exchange now says records associated with 6,444 customers were taken, with files for 5,600 protected by encryption and personal information for 844 exposed in readable form.
The official Korean-language notice lists names, mobile numbers, email addresses, national identification numbers, driver’s-license numbers, bank-account numbers and copies of identity documents among the potentially exposed fields. The exact combination varies by customer. No.1 가상자산 플랫폼, 빗썸
The attacker accessed the Daou Office groupware environment from 11:28 a.m. to 12:27 p.m. local time on 27 October. Bithumb says it detected abnormal access at 12:14 p.m., blocked the route and suspended the mobile groupware service. It reported the incident to the Korea Internet and Security Agency at 11:39 p.m. and to the Personal Information Protection Commission shortly after midnight.
Another 715 employees and contractors had information exposed. Bithumb says the groupware environment was segregated from exchange accounts, asset records and the trading system, and it has found no evidence of a direct breach of the customer database or exchange assets.
The exposed identity documents and financial identifiers increase the risk of impersonation, account-recovery fraud and targeted phishing. Bithumb is notifying confirmed customers individually and says it will support and compensate verified secondary harm under applicable law.
TOKEN RECON ASSESSMENT
This is no longer an employee-only incident. The material update is a verified customer count and a sensitive field list that includes national identification and bank data. Segregation reduced the apparent custody risk, but it does not reduce the usefulness of the stolen information for social engineering. The next evidence is the root cause, whether the 5,600 encrypted files were copied with usable keys, regulator findings and any confirmed fraud tied to the exposure.
Sources
Bithumb, customer and employee data-breach notice
