Illustrative image: a stock exchange building. Image: Wikimedia Commons. This is not a photo of Daishin Securities, Bithumb or Mirae Asset — no license-safe official image of the affected firms was available.
UPDATE — 29 October 2026, ~15:20 IST: Bithumb has now confirmed the exact scale: personal information of 844 customers was actually exposed in the 27 October hack of its in-house mobile groupware system, plus personal information of 715 employees. Of 6,444 customers associated with the breached files, 5,600 customers' data was stored in encrypted (DRM) files that could not be accessed externally, leaving the 844 exposed. The exposed customer data included, varying by customer, names, mobile phone numbers, email addresses, resident registration numbers, driver's licence numbers, account numbers and copies of identity documents, according to Asia Business Daily and Herald Business reporting Bithumb's 29 October confirmation. The intrusion ran 11:28 a.m.–12:27 p.m. on 27 October, was detected at 12:14 p.m. that day, and the mobile groupware system was suspended; Bithumb reported to the Korea Internet & Security Agency on 27 October and to the Personal Information Protection Commission early on 28 October. No loss of customer crypto funds has been reported — the breached groupware system is separate from customer trading accounts and the core exchange database was not directly compromised. The Financial Services Commission / Financial Supervisory Service on-site investigation continues.
UPDATE — 29 October 2026, ~14:30 IST: Bithumb's open question is now answered: personal information of hundreds of customers was also leaked in the 27 October hack of its in-house mobile groupware system, according to financial-industry sources reported by the Korea Herald (Yonhap), Seoul Economic Daily and Maeil Business Newspaper on 29 October. The breach was initially believed to have affected only employees; the customer leak was found belatedly while the exact scope was being analysed. Bithumb has not yet issued an official notice on the exact scale or the categories of customer data involved, and no loss of customer crypto funds has been reported — the breached system is separate from its trading platform. The Financial Services Commission and Financial Supervisory Service already have an on-site investigation under way.
UPDATE — 28 October 2026, ~08:20 IST: Mirae Asset Global Investments has now given its own account of the incident: the company says abnormal access from an external IP address affected some business-purpose systems, the access route has been blocked, and — so far — no unique identifying information, sensitive personal information or personal credit information was leaked, with no financial damage and no impact on ordinary investors, because the affected system does not serve individual customers. The incident has been reported to the Financial Services Commission and the Financial Supervisory Service, and the investigation into the exact scope continues.
TL;DR: The south korea financial firms data breach bithumb daishin story in one line: three South Korean financial firms — crypto exchange Bithumb, brokerage Daishin Securities and asset manager Mirae Asset Global Investments — confirmed data breaches on October 28, 2026, with Daishin alone reporting personal and credit information of 38,490 customers leaked, as the country's top financial regulator warned of a wider wave hitting the sector.
📌 KEY HIGHLIGHTS
- Three South Korean financial firms reported breaches on Wednesday, October 28, 2026: Bithumb, Daishin Securities and Mirae Asset Global Investments.
- Daishin Securities confirmed personal and credit information of 38,490 customers leaked, including names, emails, addresses and encrypted account and phone numbers.
- Bithumb said its in-house mobile system was hacked and personal information leaked; it is still checking whether member data was included.
- Financial Supervisory Service chief Lee Chan-jin said a "significant hacking incident" hit major financial investment firms, warning the damage may go beyond the three named firms.
- The breaches extend a wave that has already hit 16 South Korean financial firms, with around 100,000 cases of data leaks reported so far.
What happened?
Three South Korean financial firms reported data breaches on Wednesday, October 28, 2026, according to Yonhap News Agency, as reported by Reuters. Crypto exchange Bithumb said its in-house mobile system had been hacked and personal information leaked, and that it was investigating whether member data was included. Brokerage Daishin Securities said about 38,490 pieces of customer information had been leaked. Asset manager Mirae Asset Global Investments also confirmed a hacking incident, with authorities assessing the situation.
The announcements landed the same day South Korea's top financial regulator spoke out. Financial Supervisory Service governor Lee Chan-jin told a meeting of bank holding company chairpersons that "a significant hacking incident occurred at major financial investment firms the previous day" and urged the sector to prioritise IT security, warning that AI-assisted hacking makes vulnerabilities easy to find and simultaneous attacks a constant threat. According to Aju Press, Lee's remarks pointed to hacking damage at financial investment firms beyond the three already named, raising concerns that the incident is wider than first reported.
The three firms: what leaked
| Firm | What was confirmed | Scale / status |
|---|---|---|
| Bithumb (crypto exchange) | In-house mobile system hacked; personal information leaked | Hundreds of customers' personal information also leaked (industry sources, 29 Oct); exact scale and data categories not yet officially confirmed |
| Daishin Securities (brokerage) | Personal and credit information leaked via a server linked to non-face-to-face account openings | 38,490 customers confirmed; individual notification planned |
| Mirae Asset Global Investments (asset manager) | Hacking incident confirmed | Company says no sensitive or unique identifying information leaked so far; business-purpose systems only; reported to FSC/FSS; scope still being investigated |
Daishin Securities gave the fullest account. The firm said abnormal access by a hacker was detected on October 17 on a server linked to opening non-face-to-face brokerage accounts for discretionary investment services. It immediately blocked the IP addresses used in the attack, reported the incident to financial regulators and investigated with the Financial Security Institute. After reviewing roughly 60,000 signals disguised as normal service requests over ten days, it confirmed on October 26 that customer information had leaked.
Illustrative image: server racks in a data centre. Image: Wikimedia Commons. The breaches hit the firms' internal and customer-facing systems, not their core trading platforms, according to the companies.
The eight types of data leaked at Daishin were customer names, email addresses, postal addresses, telecommunications IDs, bank names, and — in encrypted form — deposit and withdrawal account numbers, Daishin Securities comprehensive account numbers and mobile phone numbers. The company said it had found no evidence so far of secondary damage such as phishing using the leaked information, and that the hacker did not gain illegal access to its core business systems. It apologised to affected customers and said it would notify each of them individually.
Why it matters for World readers
This is not an isolated incident. South Korea's Financial Services Commission said earlier this month that a wave of hacking attacks had hit 16 financial firms, including banks, causing around 100,000 cases of data leaks so far. Earlier cases in the wave included Shinhan Bank, with about 25,700 customers affected, and savings banks such as Yegaram. A separate Mirae Asset Life Insurance breach, confirmed on October 26 after unusual activity was detected on October 25, is part of the same wider wave — a different Mirae Asset entity from the asset manager named today.
The pattern matters beyond Korea. In each case so far, attackers reached peripheral or customer-facing systems rather than core banking platforms — and regulators are now treating the sector's forgotten web portals and account-opening systems as the real perimeter. Our earlier coverage of a major bank breach, SBI's confirmed customer data leak, showed the same lesson: the damage is measured in exposed personal data, not stolen money, and the risk to customers comes afterwards, through phishing and identity fraud attempts.
Should you care? Our verdict
✅ Yes — if you hold accounts with any South Korean financial firm, watch for official contact. Daishin says it will notify affected customers individually, and no secondary damage has been confirmed yet. ⏳ Watch for: Bithumb's finding on whether member data was included, Mirae Asset Global Investments' details, and any regulator statement on firms beyond the three named — the FSS chief's warning suggests more names may follow.
FAQs
Which South Korean financial firms were hacked on October 28, 2026? Three firms confirmed breaches that day: crypto exchange Bithumb, brokerage Daishin Securities and asset manager Mirae Asset Global Investments, according to Yonhap News Agency as reported by Reuters.
How many Daishin Securities customers were affected? Daishin Securities confirmed personal and credit information of 38,490 customers leaked, including names, emails, addresses and telecom IDs, plus encrypted account numbers and mobile phone numbers.
Was Bithumb customer money affected? Bithumb has said only that its in-house mobile system was hacked and personal information leaked; it is still investigating whether member data was included, and no loss of customer funds has been reported.
Is this part of a bigger wave of attacks? Yes. South Korea's Financial Services Commission said earlier in October that hacking attacks had hit 16 financial firms with around 100,000 cases of data leaks so far, and the Financial Supervisory Service chief warned on October 28 that damage may extend beyond the firms named so far.
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Sources
Reuters (via Yonhap News Agency), "Three South Korean financial firms including Bithumb report data breaches", October 28, 2026; Seoul Economic Daily, "Daishin Securities Hack Exposes Data of 38,490 Customers", October 28, 2026; Aju Press, "Lee Chan-jin Reports Hacking Incidents at Major Financial Firms" and "Daishin Securities Reports Data Breach Affecting 38,490 Customers", October 28, 2026.
Asia Business Daily — "Mirae Asset Global Investments Hit by Hacking Attack... No Sensitive Information Leaked" (28 October 2026, company statement).
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