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Four financial and cryptocurrency companies disclosed separate security incidents involving personal records and internal information. Coinbase, Bithumb, Mirae Asset Global Investments and Daishin Securities reported the incidents as authorities examined financial-sector cyber threats in South Korea.
According to Reuters, the three South Korean cases came to public attention on October 28. Coinbase separately confirmed exposure of some customer contact details through analytics provider Amplitude. The exchange said attackers had not entered its own systems and customer funds remained safe.
Coinbase traced the exposure to Amplitude, its third-party analytics provider. The exposed material included contact details for a small subset of Coinbase customers and information from other clients.
The exchange did not provide an affected customer count or a full list of exposed fields. Instead, it said its security checks found no unauthorized access to Coinbase systems. It also began notifying affected customers by email under applicable legal requirements.
Hardware wallet maker Foundation disclosed a separate incident. Attackers compromised Cloudflare API keys and sent fraudulent emails that appeared to come from company domains. Foundation said Passport devices and customer funds remained secure.
Together, the Coinbase and Foundation disclosures involved external services rather than confirmed compromises of customer asset storage. Both companies said customer funds remained safe.
In South Korea, Bithumb discovered unauthorized access to its mobile workplace communication system on October 27. The exchange alerted the Korea Internet & Security Agency and the Personal Information Protection Commission that day.
Bithumb confirmed exposure of personal information but continued checking whether any customer account records appeared among the affected data. The company said its workplace network operates separately from the systems that handle cryptocurrency transactions.
That separation means the intruder could not reach customer digital assets through the affected workplace system, according to Bithumb. The incident followed earlier reports involving 16 financial businesses, including Gopax operator Streami and virtual asset service provider Prabang.
Mirae Asset Global Investments also reported unauthorized viewing of information on internal web systems. The company said general investors' personal and credit records remained untouched, including passport numbers and other sensitive identity details.
Mirae Asset reported no financial losses, malware or service disruptions. It blocked the access routes, informed regulators and hired an outside cybersecurity firm. Investigators found no evidence of direct access to its databases or servers.
Read More: Taiwan Targets Coinbase and Kalshi Over Suspected Election Gambling
Daishin Securities reported the largest confirmed customer exposure among the four companies. Hackers accessed personal and credit details for 38,490 customers through a server linked to remote brokerage account applications.
The brokerage detected suspicious traffic on October 17 and blocked the attackers' IP addresses. Working with the Financial Security Institute, it reviewed roughly 60,000 requests over ten days and confirmed the breach on October 26.
The records contained names, addresses, emails, bank details, account numbers, communication IDs and phone numbers. Daishin said it had encrypted bank account numbers, securities account numbers and mobile numbers. It found no secondary damage or intrusion into core systems.
Chief executive Jin Seung-wook apologized and promised stronger access controls and detection measures. The company said it would notify affected clients and compensate qualifying losses through legal procedures.
Separately, Binance co-founder Changpeng Zhao warned that leaked contact information can support phishing, SIM swapping and social engineering. He advised unique passwords, authenticator apps or passkeys, withdrawal controls and regular checks of login sessions and API permissions.
Zhao also recommended separate contact details for crypto accounts and mobile carrier protections against number transfers. For affected customers, the guidance included reviewing withdrawals, removing suspicious sessions and checking exposed email addresses through Have I Been Pwned.
The four incidents affected different services and types of information. Coinbase and Bithumb reported no intrusion into their core asset systems, while Mirae Asset said investor records remained secure. Daishin confirmed the exposure of 38,490 customer records. Zhao urged stronger authentication, careful account monitoring and safeguards against phishing.
