South Korean brokerage Daishin Securities says hackers obtained personal information on 38,490 customers. Its disclosure came on the same day financial regulators began on-site investigations into a separate breach at crypto exchange Bithumb, and promised that customers would be fully compensated if they lose money.
Daishin posted a notice and apology on its website on the morning of 28 October. The Financial Services Commission (FSC) and Financial Supervisory Service (FSS) set out their response to the incidents in a joint statement the same day. Both documents are in Korean, and the quotes here are TSN translations.
What Daishin says was taken
According to the notice, Daishin detected attempts at illegal access from outside on 17 October 2026. After investigating, it confirmed on 26 October that personal and credit information had leaked. It puts the total so far at 38,490 people.
The notice lists eight types of data: customer name, email address, home address, telecom ID and bank name, plus three items it says were encrypted: linked bank account numbers, Daishin account numbers and mobile phone numbers. It says the exact items differ from person to person. Some reports have described the leak as names, emails and phone numbers only, but Daishin’s own list is longer.
Daishin says it has found no secondary harm so far. It says it blocked the hacker’s IP address and a second address used to get round that block, ran extra vulnerability checks, tightened monitoring and reported the breach to regulators. The notice is signed by chief executive Jin Seung-wook. It also includes a button customers can use to check whether their data was involved.
Bithumb and other firms
At an emergency meeting chaired by the FSC on 28 October, Bithumb reported “abnormal external access”, according to the regulators. It said this had leaked information about staff at Bithumb, its subsidiaries and partner companies. Whether any user data was involved is still being checked.
The regulators say the breached system supports staff work and is not Bithumb’s core crypto trading system. So far, they say, there is no confirmed leak of wallet addresses or other data that could be used for fraudulent payments or to move assets. Bithumb told CoinDesk that customer crypto cannot be reached through this breach. Yonhap reported, citing an industry source, that some customer data had leaked, but the regulators have not confirmed that.
The FSC/FSS statement also names Mirae Asset Life and Mirae Asset Global Investments as firms that recently reported incidents. CoinDesk reports that Mirae says investor information was not affected. FSS governor Lee Chan-jin told reporters he understood that major financial investment companies had “experienced overall hacking incidents” the day before, CoinDesk reports. Neither the companies nor the regulators have said who was behind the attacks or whether they are linked.
How regulators plan to contain the damage
The FSC, the FSS and the Financial Security Institute, the sector’s security agency, have started on-site investigations and are sharing information, the statement says. If customers suffer losses, the FSC says it will make sure firms take protection measures such as “full compensation”.
The FSC also plans to raise security at crypto firms and other businesses outside the Electronic Financial Transactions Act to the level required of banks. The FSS and the institute will look closely at the Mirae companies and Daishin.
Why a leaked staff system can still hurt customers
The incidents share a pattern: none of the firms says its trading core was breached. Daishin’s leak still matters, because a name, address and bank name are enough for a convincing scam call. A message that knows which bank a customer uses and what their email address is will sound like it comes from Daishin. That is why the notice spends as much space on phishing as on the breach itself. It warns customers against calls or texts claiming to be from financial firms, unknown links, app-install requests and anyone asking for financial or login details or offering “compensation” for the leak.
Bithumb’s case is a reminder that staff systems are part of the attack surface too. Employee data can be used to impersonate staff to customers or to target insiders, even when wallets are untouched. Similar warnings followed the So-net member data breach in Japan this week, and email-address leaks such as the AfD breach logged by Have I Been Pwned. In crypto, attacks often move from data theft to drained wallets, as Bloom’s users found. Korean banks have also faced attackers using an open-source AI hacking tool, according to CrowdStrike.
What customers can do
Daishin directs worried customers to its financial support centre on 1588-4488 or 1544-4488. Its notice reminds them that they can claim damages, including statutory damages without proving the exact amount of loss, or apply for dispute mediation through the Personal Information Protection Commission. Whether Bithumb users were affected, and how the Mirae incidents happened, depends on the on-site investigations that started this week.
Sources
- Daishin Securities: notice of personal (credit) information leak and apology (28 October 2026, Korean)
- Financial Services Commission and Financial Supervisory Service: emergency meeting on hacking incidents at Bithumb and other virtual asset firms (28 October 2026, Korean)
- CoinDesk: Bithumb hacked through employee system as South Korean financial firms face cyberattacks (28 October 2026)
- Yonhap: report on the Daishin and Bithumb incidents (28 October 2026)
Related stories
- Bloom Says Attackers Drained 9,408 SOL From 49 Users’ Wallets
- So-net Says Hack Exposed 2.59m Records and 54,401 Mail Passwords
- Have I Been Pwned Says AfD Breach Exposed 345,439 Email Addresses
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