# Bithumb Data Breach Exposes Users to Targeted Phishing Attacks Unauthorized access to internal workplace tools triggers widespread security concerns across South Korean financial firms. - **Source:** [CryptoPotato](https://brifing.si/source/bd22636b-ec8d-42a8-8cca-1937c50e0f6c) - **Published:** 2026-10-28 - **Topic:** [Software & Engineering](https://brifing.si/c/engineering) - **Original article:** - **On Brifing:** https://brifing.si/s/491f0e50-b2d0-48ed-977e-4909146bc8e3 ## Unauthorized Internal System Access Bithumb, South Korea's second-largest crypto exchange, confirmed an unauthorized party accessed its internal mobile groupware system on October 27. The breach, identified on October 28, remains under investigation to determine the exact scope of compromised customer data. This incident highlights critical vulnerabilities within internal corporate communication tools used by major financial institutions. ## Broader Financial Sector Impact The security incident extends beyond Bithumb, affecting other major financial entities including Daishin Securities and Mirae Asset Global Investment. Daishin Securities reported that information for over 38,000 customers, including names, emails, and phone numbers, was exposed. The Financial Supervisory Service is currently investigating these concurrent breaches and has deployed on-site teams. ## Regulatory Pressure on Security FSS Director Lee Chan-jin emphasized the growing threat of AI-driven hacking, which facilitates simultaneous attacks on multiple targets. He urged bank holding company chairmen to prioritize IT security at the board level. The regulator is demanding immediate improvements in security capabilities to counter the increasing frequency of sophisticated cyber threats facing the sector. ## Expert Advice on Mitigation Binance co-founder Changpeng Zhao advised users to minimize shared information and secure accounts against potential phishing. He recommended using unique email aliases for every exchange and replacing SMS-based codes with hardware keys or passkeys. These measures aim to mitigate risks associated with SIM-swapping and social engineering attacks targeting leaked user contact details. ## Rising Trend of Breaches The Bithumb incident follows a series of security disclosures across the crypto industry. Hardware wallet provider Foundation recently reported 23,000 phishing emails sent via its domain after API key compromises on Cloudflare. These recurring events demonstrate that even established firms struggle to maintain perimeter security against persistent and evolving unauthorized access attempts. ## Historical Data Exposure Incidents Recent months have seen significant data leaks, including the theft of shipping information for 67,000 users from a Trezor provider, ShipMonk, in August. Additionally, Keystone Wallet reported unauthorized access to its website, exposing customer shipping data. These incidents underscore the persistent risk to user privacy even when core wallet passwords remain uncompromised. ## Conflicting Reports on Amplitude A recent incident involving Amplitude, a Coinbase vendor, led to claims by SlowMist that 70,000 users had their contact details exposed. However, Coinbase formally rejected the breach label, stating no evidence of unauthorized system access was found. This discrepancy highlights the complexities of verifying security claims within interconnected third-party vendor ecosystems. ## Strategic Security Outlook The convergence of these breaches suggests that attackers are increasingly targeting the supply chain and internal operational tools rather than direct exchange protocols. As phishing risks escalate, the responsibility shifts toward both institutional oversight and individual user vigilance. Boards must now treat cybersecurity as a fundamental operational pillar to prevent further systemic data exposure. ## Sources covering this story - https://cryptopotato.com/bithumb-users-face-phishing-risks-after-reported-data-leak/ — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._