Ethereum Classic’s second 51% attack Thursday resulted in a massive reorganization of 4,236 blocks and successful double-spend of $1.68 million worth of cryptocurrency, according to an investigation by Bitquery.
The attacker tried to double-spend 465,444 ethereum classic (ETC), worth approximately $3.3 million, but only successfully double-spent 238,306 ETC, worth $1.68 million, according to the report.
An additional 14,200 ETC were also claimed by the attacker via block rewards during the event.
Bitquery found the hashpower required for the attack was probably bought from the same source as for the first attack: Nicehash DaggerHashimoto.
Thursday's attack is the second on the Ethereum Classic platform within five days. The first attack occurred on Aug. 1 and was originally thought to be the result of software complications.
Ethereum Classic Labs, the core development organization behind Ethereum Classic, announced Friday that it has retained law firm Kobre & Kim to investigate and pursue criminal charges against the perpetrators of both 51% attacks, according to a press release shared with CoinDesk.
Update (August 7, 16:22 UTC): This article has been updated additional information about Ethereum Classic Labs’ response to the attacks.