South Korean exchange Bithumb confirmed unauthorized access to an internal employee system and is checking whether customer data was exposed. Coinbase says a third-party vendor incident, not a breach of its own systems, exposed some customer contact data, while two other South Korean firms also reported incidents.
Bithumb confirmed unauthorized access to its internal employee mobile groupware system, which runs through the third-party platform Daou Office. The breach exposed employee names, work email addresses and mobile phone numbers. The exchange is reviewing system records to find out whether customer information was also exposed.
CryptoPotato, citing Yonhap News Agency, reports that Bithumb detected abnormal access by an outsider without authority on October 27. Bithumb also reported the incident to the Korea Internet & Security Agency and the Personal Information Protection Commission.
Coinbase points to a vendor incident
Coinbase denied that its own systems were breached. It said a security incident at analytics vendor Amplitude affected a small subset of Coinbase customer contact data, along with data from other Amplitude customers.
Blockchain security firm SlowMist reported that around 70,000 Coinbase users may have been affected, with email addresses and phone numbers exposed. However, Coinbase has not confirmed that figure.
Daishin and Mirae Asset report incidents
Brokerage firm Daishin Securities confirmed on October 28 that personal and credit information belonging to 38,490 customers had been exposed. The company first detected suspicious activity on October 17 and later found more than 60,000 harmful requests over 10 days.
Mirae Asset Global Investments detected unauthorized access to some of its web systems. The company said only internal business data was exposed, with no evidence that investor details or personal credit information leaked.
Financial Supervisory Service Governor Lee Chan-jin said at least 16 financial firms had faced cyberattacks in October, leading to around 100,000 cases of data leaks.
CZ urges users to protect themselves
Binance co-founder Changpeng Zhao said users may not be able to prevent leaks but can take steps to protect themselves. He noted that leaked exchange data mostly feeds phishing and SIM-swapping attacks. He recommended a unique email alias for each exchange, and hardware keys or passkeys instead of SMS codes.
Sources: Coinpedia Fintech News, CryptoPotato
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