Bithumb, one of South Korea’s leading cryptocurrency exchanges, has issued a public warning to its Korean user base following a significant data breach at SK Telecom, the country’s largest mobile carrier. The breach, which came to light on April 19, has raised serious concerns over the security of customer information, particularly in relation to unauthorized SIM swaps and potential compromise of crypto accounts.
SK Telecom Confirms Breach Tied to Malware
SK Telecom confirmed in a statement on April 22 that the breach was the result of malicious code affecting parts of its infrastructure. The malware targeted USIM-related data — information tied to user identity and mobile authentication prompting immediate actions from the carrier to isolate infected systems and remove the threat.
“Although no confirmed cases of data misuse have been identified, precautionary measures have been taken,” SK Telecom stated via its official Twitter account.
The carrier, which services approximately 31.5 million mobile users (about 37.5% of the South Korean market), is currently conducting a full system audit and has intensified efforts to block illegal SIM swaps and detect abnormal authentication attempts.
Bithumb Boosts Security and Urges User Action
In response to the breach, Bithumb has heightened its internal security protocols and urged its users to take immediate precautions. In a press release issued Thursday, the exchange stated that it is actively monitoring for suspicious activity, implementing multi-layered protections, and working to prevent any unauthorized access to user accounts.
The company strongly advised users to:
- Update passwords and enable two-factor authentication (2FA);
- Check for suspicious login attempts;
- Remain alert for phishing messages or SIM-related scams;
- Use secure mobile verification methods where possible.
Broader Implications for Korean Crypto Users
The incident once again highlights the interconnected risks between telecom providers and digital finance platforms, particularly in a country with one of the world’s highest crypto adoption rates. SIM swap attacks have become a favored method for hackers targeting exchange accounts, and breaches at carriers like SK Telecom could potentially pave the way for large-scale identity theft or crypto theft.
As a preventive step, Korean regulators may soon tighten compliance rules around mobile authentication systems, while exchanges like Bithumb brace for increased scrutiny and user anxiety.
While no direct misuse of the leaked data has yet been confirmed, the Bithumb–SK Telecom breach connection serves as a critical wake-up call for crypto users across South Korea. As exchanges and telecom providers double down on cybersecurity, users are urged to remain proactive in safeguarding their digital identities and financial assets.
