Bithumb Hit by Data Breach as Cyberattack Wave Sweeps South Korean Finance
Author: Crypffalo Research · 10:54 28/10/2026
Bithumb confirmed hackers breached its internal mobile system and exposed personal data. No crypto losses have been reported; 16 Korean financial firms have been hit in the wave.
South Korean crypto exchange Bithumb confirmed on Oct 28 that hackers breached its internal mobile system and exposed some personal information. The exchange said it is still assessing the scope and has not ruled out that member data was included.
Bithumb is one of South Korea's two largest crypto exchanges. It disclosed the incident on the same day as brokerage Daishin Securities and asset manager Mirae Asset Global Investments, according to Yonhap and Reuters.
Key takeaways
- Incident: An unauthorized outside party accessed Bithumb's internal mobile groupware system.
- Data: Personal information was exposed; the exchange has not disclosed how many people are affected.
- Funds: As of publication, there are no reports of customer crypto being withdrawn or wallets being drained.
- Wider wave: South Korea's Financial Services Commission (FSC) said 16 financial firms have been hit, with around 100,000 data leak cases.
- Market: Bitcoin held near $80,800, up about 1% over 24 hours.
What happened at Bithumb
According to the Kyunghyang Shinmun, Bithumb discovered the leak on Oct 27 and announced it on the morning of Oct 28, Korea time. The exchange described it as "abnormal access by an external unauthorized party" to an internal mobile groupware system.
Bithumb said it notified the Korea Internet & Security Agency (KISA) and the Personal Information Protection Commission right after spotting the leak. It has not said what kind of data was exposed or how many users are involved.
What is confirmed and what remains open:
- Confirmed: An internal system was breached, personal information leaked, and authorities were notified.
- Under investigation: Whether customer data was part of the leak, the full scope, and who was behind the attack.
- No information yet: Bithumb has not commented on whether user crypto assets were affected.
A hacking wave across Korean finance
The Bithumb breach is the latest in a string of cyberattacks on South Korea's financial sector since late September. The Korea Times reported the attacks are suspected to be AI-assisted, raising concerns over the industry's ability to defend itself.
Key dates:
- Sep 30: A breach at Shinhan Bank kicks off the wave.
- Oct 17: Daishin Securities detects hackers accessing a server tied to online account openings.
- Oct 27: Bithumb discovers the leak.
- Oct 28: Bithumb, Daishin and Mirae Asset Global Investments disclose incidents.
Daishin Securities confirmed that data on 38,490 customers leaked, including names, email addresses and phone numbers. Korean media also noted earlier security incidents at Streami, the operator of the GOPAX exchange.
Seoul's Science Ministry and KISA have urged website operators to check for PHP flaws that let attackers run commands on a server without logging in, Reuters reported.
What it means for crypto markets
Markets barely reacted. Bitcoin traded around $80,800 and Ether near $2,350, both up roughly 1% as traders wait for the Federal Reserve's rate decision.
- Bull case: If Bithumb confirms only internal data leaked and no funds were touched, the fallout stays mostly reputational and regulatory.
- Risk case: If customer data was exposed at scale, users could face targeted phishing, and regulators may tighten security rules for exchanges.
Leaked personal data rarely costs users coins directly, but it fuels scams that impersonate exchanges. Similar impersonation campaigns have followed data incidents at other major exchanges in the past.
What to watch next
- An official update from Bithumb on the number of affected users and the type of data exposed.
- Findings from the FSC and KISA on the wider attack wave.
- The Fed's rate decision, due at 2 p.m. ET on Oct 28 (1 a.m. Oct 29, GMT+7) – see the economic calendar.
- Derivatives positioning around the Fed – track real-time liquidations.
Frequently Asked Questions
Were funds stolen from Bithumb?
As of publication, there are no reports of customer crypto being withdrawn without authorization. The confirmed information relates only to personal data.
What should Bithumb users do?
Be wary of emails, texts or calls claiming to be from Bithumb. Turn on two-factor authentication and never share one-time codes with anyone.
Why are so many Korean financial firms being hit at once?
Authorities have not named the attackers. Korean media say the attacks are suspected to be AI-assisted, and the government's PHP vulnerability warning is one line of inquiry being discussed.
*This content is for information only and is not financial advice.*
Tags: Bithumb, South Korea, Security, Hack
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