Bithumb Says 6,444 Customers Were Affected by Data Leak, 844 Had Personal Information Exposed

South Korean cryptocurrency exchange Bithumb disclosed the scale of customer information exposed in a recent hacking incident and issued a formal apology.

Bithumb said on October 29 that an unauthorized external party gained access to Dow Office, its internal mobile groupware system, on October 27, leading to the leak of some customer information. The company said it would begin notifying affected customers individually later that day and that users can check on Bithumb’s website whether their personal information was exposed.

Bithumb said 6,444 customers were affected in total. Of those, 844 had personal information exposed. The remaining 5,600 were tied to encrypted DRM files that could not be accessed externally, meaning their personal information was not exposed. The leaked data included names, mobile phone numbers, email addresses, resident registration numbers, driver’s license numbers, bank account numbers and copies of identification cards. The scope of the exposed information varied by customer.

Bithumb said it believes the leak occurred as employees used the internal mobile groupware system for work purposes. A company official said the compromised groupware platform was an internal business system separate from customer exchange accounts and asset holdings. No signs have been found so far that the exchange’s services or customer database were directly breached.

Bithumb Chief Executive Officer Lee Jae-won apologized for causing concern and anxiety among customers. He said the company would do its best to provide relief and compensation if secondary damage is confirmed for customers whose personal information was exposed.

Lee added that Bithumb would use the incident to reexamine the security of its entire internal business infrastructure from the ground up and focus on preventing a recurrence.