The Ethereum Classic Vision (ETC) Network briefly goes down for maintenance on August 1 after experiencing a possible blockchain reorg of 3,693 blocks. Several industry players associated with the network took to Twitter to inform the community about the issue. Both ETC and the founder of Ethereum Classic Labs, James Wo, confirmed the issue on their official Twitter accounts.
Later on, an official diagnosis report was released to explain what actually happened. According to the report, there was about 3,000 block-insertion by a miner who was mining for about 12 hours on Core-Geth. The report claims the miner was either mining offline or the total difficulty could have exceeded current network difficulty. The approximately 3,000 blocks were inserted on block number 10904146, whereas the address used is 0x75d1e5477f1fdaad6e0e3d433ab69b08c482f14e.
Any transactions that occurred during the time were possibly not mined in the order they were intended to be mined, says the report. It added that any transactions that aren’t mined will be re-submitted to the mempool during a re-org. The report recommends that miners should “continue mining the chain as-is”, as the chain is following Proof-of-Work with the longest chain as intended.
Reorg is a feature in a blockchain that allows the network to roll back. According to the report the incident doesn’t seem there was a major double-spend attack. As it stands now, it is not known whether an attacker has profited from this incident. However, mining solutions provider, Bitfly has advised all crypto exchanges to halt deposits and withdrawals of ETC.
Though the team claims the incident doesn’t appear actively malicious, they still agree that it might as well be a deliberate attack. This is not the first time the Ethereum Classic Network is experiencing a reorg. It was reported in 2019 that ETC has experienced a “multiple 100+” reorg attack that enabled the attacker to spend 88,500 ETC, raising concerns about the Proof-of-Work mining model.