Bithumb and two South Korean financial firms report data breaches

On October 28, 2026, Bithumb, South Korea's second-largest crypto exchange, disclosed hackers accessed its internal mobile employee system. Daishin Securities reported a breach leaking personal data of 38,490 customers, while Mirae Asset Global Investments confirmed a separate hacking incident. The Financial Services Commission earlier reported attacks on 16 financial firms causing around 100,000 data leaks. Regulators urged operators to check for PHP vulnerabilities.

Bithumb data breach

• ▪An industry source told Yonhap that some personal information belonging to Bithumb customers had been leaked
• ▪Bithumb is South Korea's second-largest crypto exchange
• ▪An unauthorized outside party accessed Bithumb's internal mobile groupware system, resulting in a leak of personal information

South Korean financial sector breaches

• ▪Bithumb, Daishin Securities, and Mirae Asset Global Investments reported data breaches on October 28, 2026
• ▪South Korea's Science Ministry and the Korea Internet & Security Agency urged website operators to check for recently disclosed flaws in PHP that let attackers run commands on a server without logging in
• ▪The Financial Services Commission said earlier in October 2026 that hacking attacks on 16 South Korean financial firms, including banks, had caused around 100,000 data leaks
• ▪Mirae Asset Global Investments confirmed a hacking incident
• ▪Daishin Securities said it would compensate customers for any damage resulting from the data leak affecting 38,490 customers in accordance with the law
• ▪South Korean financial authorities have begun an inspection of the Mirae Asset Global Investments hacking incident reported on October 28
• ▪Daishin Securities detected signs of unauthorized access last week and discovered that personal information of 38,490 customers, including names, email addresses and mobile phone numbers, was leaked

Coinbase vendor incident

• ▪A security incident at analytics vendor Amplitude on October 28, 2026, did not affect Coinbase customer funds
• ▪A security incident at analytics vendor Amplitude exposed some Coinbase customers' contact data on October 28, 2026
• ▪Changpeng Zhao is the founder of Binance

User security recommendations

• ▪Changpeng Zhao warned that leaked exchange data is mostly used for phishing, SIM swapping, and social engineering
• ▪Changpeng Zhao stated that leaked addresses and holdings data have led to real-world extortion and robberies
• ▪Changpeng Zhao urged users to sign up to each exchange with a unique email alias
• ▪Changpeng Zhao urged users to avoid text message-based two-factor authentication
• ▪Changpeng Zhao urged users to ask their phone carrier for a number lock

Bithumb's 2026 setbacks

• ▪Bithumb has set out a three-stage plan to list on the stock market in 2028
• ▪Bithumb CEO Lee Jae-won was booked as a bribery suspect in June 2026 over the alleged hiring of a National Assembly member's son
• ▪A Seoul court blocked Bithumb's six-month partial suspension in April 2026
• ▪In February 2026, Bithumb mistakenly credited 695 users with a total of 620,000 BTC, worth about $43 billion at the time, during a promotion meant to hand out small cash rewards
• ▪In March 2026, South Korea's Financial Intelligence Unit fined Bithumb 36.8 billion won ($24.6 million) and ordered a six-month partial suspension over anti-money laundering failures

Perspective of Changpeng Zhao (Binance founder)

• ▪Changpeng Zhao warned that leaked exchange data is mostly used for phishing, SIM swapping, and social engineering
• ▪Changpeng Zhao stated that leaked addresses and holdings data have led to real-world extortion and robberies