Blockchain Capital executive loses $6.3m in SIM-swap attack

Co-founder and managing partner of the crypto fund Blockchain Capital, Bart Stephens, has filed a lawsuit against an anonymous hacker who siphoned off $6.3 million in various digital assets through a SIM-swap. Forbes reports.

According to court filings, in May the attacker used publicly available information about Stephens to bypass the mobile-carrier’s security checks and change passwords on his accounts.

The hacker then ported the victim’s mobile number to a SIM card on a new device. This allowed him to reset passwords and bypass two-factor authentication on several of Stephens’s crypto wallets, granting him full access. In total, he withdrew $6.3 million.

The hacker also attempted to steal $14 million in Bitcoin and Ethereum from the victim’s cold wallet, but was blocked by an employee of Blockchain Capital who received a transaction notice. 

The mobile carrier confirmed the SIM swap the day after the theft.

About half of the stolen assets were transferred by the hacker to cryptocurrency mixers. 

According to FBI estimates, SIM-swapping is becoming an increasingly common form of attack. In 2022, attackers using it collectively stole $72 million. 

As reported in March 2023, a married couple were found guilty in cryptocurrency fraud via a SIM swap totaling $250,000. They were sentenced to varying prison terms and ordered to pay $282,000 in compensation each.