Breach · · 3 min read
Bithumb: ID numbers and ID copies of 844 customers leaked through an internal work app
Korean crypto exchange Bithumb says a break-in at its internal mobile work system exposed details of 844 customers, including ID numbers and copies of ID documents.
Bithumb, one of South Korea’s biggest crypto exchanges, says someone broke into an internal mobile work app its staff use and took files that included customer details. For 844 customers, that includes resident registration numbers and copies of ID documents. Bithumb says trading accounts and funds sit on separate systems. If you have a Bithumb account, here’s what is known and what to do.
What happened
Bithumb says the break-in happened between 11:28 a.m. and 12:27 p.m. on October 27, 2026, in its internal mobile groupware, the work system its employees use. It spotted the unusual access at 12:14 p.m., blocked the attacker’s route in and shut the system down, The Asia Business Daily reported.
At first, the incident was believed to affect only employees. After looking further, Bithumb said on October 29 that customer information was also involved, Digital Today reported. The files appear to come from material employees saved or handled in the app during their work.
The numbers Bithumb gives are:
- 6,444 customers in total were in the affected files
- for 5,600 of them, the data was in encrypted files that Bithumb says couldn’t be opened from outside
- for 844, details were directly exposed, and the exact items vary by person
The exposed details can include name, mobile number, email address, resident registration number, driver’s licence number, bank account number and a copy of an ID document. Data for 715 employees was also taken. Bithumb says it found no sign that the exchange itself or its customer database was broken into, and it began notifying affected customers one by one on October 29. Customers can also check on Bithumb’s website whether they were affected.
The same week, brokerage Daishin Securities and asset manager Mirae Asset Global Investments also reported breaches, Yonhap reported.
What this means for you
A resident registration number with a copy of an ID is the kind of information used to prove who you are, so it can help someone open accounts or pass identity checks in your name. It can also make a fake call from “Bithumb” sound very convincing. Bithumb has warned about people posing as its staff who ask for verification codes or push you to install an app.
What you can do
- Check whether you were affected using Bithumb’s notice on its website, and read any message it sends you.
- Never share a verification code or install an app because someone claiming to be from Bithumb asked you to. Use the official customer centre if you’re unsure.
- Turn on every sign-in protection Bithumb offers and review your account’s login and withdrawal settings.
- Watch your bank accounts and credit for new accounts or loans you didn’t open, especially if your ID copy was in the leak.
- Learn the patterns. See how scammers use leaked data.
How Frame helps
Add this breach to a verified email in Frame and Frame shows what it exposed, gives you a short checklist and counts it in your exposure report. Automatic breach lookups aren’t live yet. Frame’s email aliases also let you give each financial app its own address, which makes a message to the wrong address an easy sign of a fake. Frame never collects or stores the leaked records themselves.
Sources
- The Asia Business Daily, Bithumb Internal System Hack Leaks Personal Information of 844 Customers, October 29, 2026
- Digital Today, Bithumb hacking affects 6,444 customers; 844 exposed ID numbers and copies of identification, October 29, 2026
- Yonhap News Agency, South Korean financial firms confirm data breach of customer data, October 28, 2026
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