Bithumb updates incident of breach of internal office system; information linked to 6,444 people leaked
Korean crypto trading platform Bithumb issued an announcement updating the aftermath of the hacking incident. Bithumb said that on October 27, external unauthorized personnel breached the company’s internal mobile office system (Daou Office), causing the leakage of some personal information. The system is completely separated from exchange account and asset information, and no direct breach of the trading system or customer database has been found so far. The company has strengthened real-time monitoring for abnormal transactions and withdrawals.
Bithumb disclosed that the current scale of the leak involves 6,444 people (of which information on 5,600 people was encrypted and unreadable, and the actual readable leakage involved 844 people); information of another 715 employees/partners was also leaked. The names, mobile phone numbers, email addresses, resident registration numbers, driver’s license numbers, bank account numbers, copies of ID cards and other information of the relevant people were stolen.
Bithumb stressed that it blocked access at the first opportunity, disabled the relevant system, and completed incident reporting to the Korea Internet & Security Agency and the Personal Information Protection Commission. The company is currently analyzing the specific scope of the leak.
Original sources:
Title: Bithumb hack exposes personal data of 844 customers Publisher: The Herald Business Publication date: 2026-10-29 URL: https://biz.heraldcorp.com/article/10919683 Nature of source: Media report Verification status: Relevant paragraphs read in this session, accessed on 2026-10-29 Supporting content: On October 27, external unauthorized access to Daou Office, 6,444 customers linked (5,600 encrypted and unreadable, 844 actually exposed), information of 715 employees/partners leaked, types of leaked data, the system was separated from the trading system, reporting to KISA and the Personal Information Protection Commission, blocking access and disabling the system
Title: Bithumb Leaks Personal Data of 844 Customers Including ID Numbers - CEO Issues Formal Apology (Comprehensive) Publisher: Yonhap Infomax Publication date: 2026-10-29 URL: https://en.infomaxai.com/news/articleView.html?idxno=145956 Nature of source: Media report Verification status: Relevant paragraphs read in this session, accessed on 2026-10-29 Supporting content: Leak scale and data types, 715 employees’ information, system separation, reporting and emergency measures; does not prove that all customer data were directly read
Title: 6444 Users' Information Leaked, Bithumb Says Data of 5,600 Users Unreadable Publisher: Odaily Publication date: 2026-10-29 URL: https://www.odaily.news/en/newsflash/528618 Nature of source: Media report Verification status: Full text read in this session, accessed on 2026-10-29 Supporting content: Announcement update content is consistent with the above scale, system separation and monitoring measures
ABAB AI Insight
Bithumb is one of South Korea’s major cryptocurrency exchanges. The Daou Office involved in this incident is its internal mobile collaboration office system, used for internal employee communication and document handling, and is physically isolated from the exchange’s core trading system and customer asset database. Customer information appeared in this system because employees transferred related files into it during their work.
The leak path was as follows: external unauthorized personnel accessed the system between about 11:28 and 12:27 on October 27, the company detected the anomaly around 12:14 and blocked access and disabled the system, and then reported the matter to the Korea Internet & Security Agency and the Personal Information Protection Commission. Information on 6,444 customers was linked, of which 5,600 entries could not be directly read because they were encrypted and 844 were actually exposed; information on another 715 employees and partners was also leaked. The leaked fields include names, mobile phone numbers, email addresses, resident registration numbers, driver’s license numbers, bank account numbers and copies of ID cards, with the exact scope varying by person.
A comparable reference is several similar incidents in South Korea’s financial sector, including Daishin Securities’ disclosure of the leak of information on about 38,000 customers. What is similar to those cases is that the attacks targeted internal systems or related services rather than the core trading system directly; what is different is that Bithumb explicitly distinguished between encrypted unreadable and actually readable portions, and emphasized that the trading system and assets were not directly breached.
This incident changed the exposure status of personal information belonging to Bithumb-related customers and employees: readable information of 844 customers and information of 715 internal personnel has been leaked, the company has started abnormal transaction and withdrawal monitoring, and has pledged to compensate verified losses. For users, the main risk is impersonation and phishing using the leaked information; for the exchange, the internal office system became the entry point for the data leak. Key indicators to watch are the subsequent disclosure of the specific compensation plan and whether the on-site inspection by the Financial Supervisory Service turns into a formal investigation.
ABAB News · Cognitive Law
When an internal office system is physically separated from the trading core, personal information can still be exposed because employees transfer files into it.
Encrypted storage makes some linked data unreadable directly, and the actual readable leak scale is smaller than the total linked count.
Multiple internal-system intrusions in South Korea’s financial institutions on the same day show that attack targets have shifted from the trading core to office and auxiliary systems.