Ethereum Classic Attacker Successfully Double-Spends $1.68M in Second Attack: Report

The attacker attempted to double-spend roughly $3.3 million during the second attack.

Aug 7, 2020 at 1:58 p.m. UTC
Updated Sep 14, 2021 at 9:41 a.m. UTC

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.

Nicehash DaggerHashimoto price and TH/sec during the first and second attack

Update (August 7, 16:22 UTC): This article has been updated additional information about Ethereum Classic Labs' response to the attacks.

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