- Ethereum Classic isn’t thought of as an easy target for 51 % attack, yet it was attacked again on 6 August 2020.
- According to the analysis by blockchain intelligence firms and exchanges, it’s the same attacker who attacked on July 31, 2020.
Ethereum Classic isn’t thought of as an easy target for 51 % attack, yet it was attacked again on 6 August 2020. According to the analysis by blockchain intelligence firms and exchanges, it’s the same attacker who attacked on July 31, 2020.
Bitquery’s investigation reveals that there was a reorganization of 4,236 blocks and successful double-spend of $1.68 million worth of cryptocurrency. It affected the blocks from 10935623 to 10939858, while the attacker mined the first block on 5 August 2020, which lasted for 15 hours and 6 minutes. It is reported that the attacker double spent $1.68 million through Bitfinex and another crypto service which bought the attacker 14.2K ETC as block reward, which is not included in the double spent calculation.
The First Blow to Ethereum Classic
On August 1, there was a deep reorganisation of blocks on Ethereum classic and they originally thought to be the result of software complications. The incident saw 11 malicious transactions originating from a single address which is being inserted into Ethereum blockchain allowing more than 807,000 ETC to be double-spent.
Bitquery found that the hashpower required for the attack was probably bought by the same source as first attack : Nicehash daggerHashimoto, indicating that its the same attacker. Miner distribution chart on Bitquery clearly displayed the attack.
An Elegant Double-spent
Attacker this time included seven transfers in the mined block while the total amount of transactions was 465,444 ETC (approx $3.3M). The attacker used the money from the first attack and this time he did not publish any transactions or the blocks like the last time. He/She mined blocks which included transactions in which the attacker sent the money to different accounts controlled by him. All the transactions happened during the time when he/she silently mined branched blocks.Investigation also showed that Bitfinex lost nearly $1M and it is not clear which service has lost $680K.
Tackling the Issue
On Friday, the core development organization behind Ethereum Classic, Ethereum Classic Labs announced that it retained law firm Kobre and Kim to investigate and pursue criminal charges against the masterminds of both 51% attacks. Vitalik Buterin, co-founder of Ethereum tweeted on 6 August that ETC should move to a proof-of-stake (PoS) consensus algorithm from the current proof-of-work (PoS)mechanism. Ethereum’s transaction monitoring technology, Coinpath is built to trace blockchain money flow and flagged these transactions for further investigation.