Bithumb says breach exposed personal data of 844 customers
South Korean exchange Bithumb says an intrusion into its internal groupware exposed personal data of 844 customers, including ID numbers and bank details.
EXCHANGESSECURITY & HACKSNEWS
Hana Kimura
10/29/20261 min read
South Korean crypto exchange Bithumb said on Oct. 29 that an intrusion into an internal collaboration tool exposed the personal information of 844 customers, out of 6,444 whose data sat in files the attacker reached, according to Bloomingbit and Forklog.
The attacker got into DaouOffice, a mobile groupware app staff use for messaging and file sharing, on Oct. 27 between 11:28 and 12:27 local time. Bithumb's security team spotted suspicious activity at 12:14, shut the system down and worked on fixes with its developer, Daou Technology, Forklog reported. Data on the other 5,600 customers was held in encrypted DRM-protected files that could not be opened outside the company. Information on 715 employees and partner staff was also affected.
The exposed details varied by customer and included names, phone numbers, email addresses, resident registration numbers, driver's license numbers, bank account numbers and copies of identity documents. According to Forklog, employees had moved customer data into work files stored on the platform.
Bithumb said the groupware is separate from its trading systems, exchange accounts and customer asset records, and that it has found no sign those were breached. No theft of funds has been reported. Chief executive Lee Jae-won apologized to customers. The exchange is notifying affected users individually, lets customers check their status on its website, is reviewing the security of its entire internal infrastructure and has pledged compensation if secondary damage is confirmed.
Part of a wider wave
The disclosure came as South Korea's Financial Supervisory Service looks into a string of intrusions at financial firms. Daishin Securities said personal and credit data of 38,490 customers had leaked, and Mirae Asset units also reported incidents, according to Bitcoin.com News and CoinMarketCap. FSS Governor Lee Chan-jin warned that AI tools make security weaknesses easier for attackers to find.
Leaked identity documents and bank details raise the risk of targeted phishing against exchange users, which is the main near-term concern for those affected. Bithumb, the country's second-largest exchange, is aiming for a stock market listing in 2028.
Source: Bloomingbit, Forklog, Bitcoin.com News, CoinMarketCap