Four institutions experienced data breaches in one day; CZ warns users to guard against phishing and SIM card hijacking. CZ posted that four institutions reported data breaches on October 28th. Amplitude, Coinbase's third-party data analytics service provider, experienced a security incident, resulting in the leakage of contact information for a small number of users. Coinbase stated that its system was not compromised and user funds were unaffected. South Korean exchange Bithumb suffered an external attack, resulting in the leakage of some user information. South Korean brokerage Daeshin Securities suffered a breach of information on approximately 38,500 clients, and Mirae Asset also reported a breach; South Korean financial regulators have intervened and are investigating. CZ warned that leaked data is often used for phishing, SIM card hijacking, and social engineering attacks. He advised users to enable a withdrawal whitelist, use hardware keys instead of SMS verification, and be wary of anyone who proactively contacts them claiming to handle security issues.