The two 51% attacks on the Ethereum Classic blockchain will be contested in court
When an entity or group of miners manages to own more than 51% of the mining power, the information in the transaction history can be altered, making it possible to branch out the network or causing double expenditure.
The difficulty in carrying out this type of attack is directly related to the total mining power (hashrate) of each of the blockchains that use consensus protocols based on proof of work. Therefore, such an attack in a much more powerful and decentralized network would be unlikely.
However, the hashrate on ETC’s network has been falling considerably since the beginning of the year, making such an attack easier. According to crypto51.app, the cost to lease the mining power needed to conduct a 51% attack on the Ethereum Classic network is USD 8,200 per hour.
Two attacks in the same week
The company in charge of the block scanner etherchain.org reported through its Twitter account the possibility that the Ethereum Classic network had suffered a 51% attack on its blockchain.
The attack started to be detected by an increase in transaction confirmation times, due to a desynchronization of CoreGeth nodes.
As could be seen, starting with block 10,904,146 there was a reorganization and approximately 3,693 blocks were altered causing a bifurcation, coinciding with a notable increase in hash power during the hours that the attack was carried out.
After these events, Hudson Jameson, a member of the Ethereum Foundation suggested through his twitter account: “Exchanges should pause deposits and withdrawals”, while the official website of ETC and James Wo as founder of Ethereum Classic Labs confirmed the incidence.
According to several reports from Ethermine Bitfly’s parent company, it has shown that more than 807,000 FTE were stolen between July 31 and August 1, worth $5.68 million.
Bitquery reported that the attacker spent $192,000 on bitcoin to have enough power to execute the attack.
In the second attack last Thursday, they caused a double expense of 238,306 ETC
These are not the only times that ETC suffers attacks of these characteristics, last January 2019 15 reorganizations were detected, 12 of them with double expenditure for a total of 219,500ETC.
The members of Ethereum Classic Labs will take legal action against those responsible. The law firm of Kobe & Kim will file criminal charges and CipherTrace will investigate and analyze the blockchain to identify the miners who carried out the attack.
The consensus of the work test
A proof of work based network requires a mining power to process the transactions. This is stated in the Bitcoin whitepaper written by Satoshi Nakamoto, making it clear that half of the network must be “honest” workers.
“If most of the CPU power is controlled by honest nodes, the honest string will grow faster and outperform any competing string."
The evolution of mining gave way to the manufacture of specialized hardware, called ASIC chips and the emergence of groups of mining pools to solve blocks by pooling computing power and sharing the rewards
These large groups are the potential threat to any cryptocurrency using POW algorithms, as they make it more likely to reach a hash rate of over 51% and exploit this vulnerability.