A hacker stole about $340 million worth of Bitcoin from a cryptocurrency settlement network before returning most of the funds after the security flaw behind the attack was fixed.
The incident affected Liquid Network, a Bitcoin settlement platform launched by crypto infrastructure company Blockstream in 2018. The network is used by cryptocurrency exchanges and other financial institutions to move Bitcoin more quickly between participants.
Liquid temporarily paused operations while the breach was investigated.
The attacker has been described as a “white hat” hacker, a term generally used for hackers who uncover security weaknesses rather than exploiting them purely for financial gain. Reports said the hacker agreed to return the stolen Bitcoin if Blockstream fixed the vulnerability that allowed the attack to happen.
The hacker reportedly exploited the flaw to withdraw around 4,000 Bitcoin, valued at approximately $340 million at the time.
Former Blockstream executive Samson Mow said on September 7 that the vulnerability had been fixed and roughly 3,400 Bitcoin had already been returned.
That means around 600 Bitcoin, valued at approximately $47 million, remained under the hacker’s control.
Liquid Network said it would keep operations paused while the incident was fully resolved. Mow also said further fixes and security improvements would be introduced before the network resumed normal operations.
Despite most of the stolen Bitcoin being returned, the attack ranks among the largest cryptocurrency thefts reported this year and one of the biggest digital asset heists on record.
The incident follows several other unusual cryptocurrency thefts. Just over a month earlier, hackers reportedly stole $38 million in Bitcoin from about 500 Coldcard hardware wallets by exploiting a vulnerability affecting certain Mk3 devices. Around 594 Bitcoin were taken in roughly 25 minutes.
In another case earlier this year, South Korean authorities seized nearly $5 million in cryptocurrency from a suspected money launderer but accidentally revealed the wallet’s recovery phrase in evidence photographs. Someone later used the exposed phrase to steal approximately $4.8 million of the seized cryptocurrency.