51% cryptocurrency attack illustration
Illustration by Doncho Karaivanov for The Chain Bulletin

On August 30, the Ethereum Classic organisation confirmed another 51% attack via Twitter. In the tweet, developers suggested that miners, exchanges, and other service providers keep confirmation requirements levels well above 7K until the current risk to the network is mitigated.

Earlier this month, ETC suffered another two 51% attacks with reorganisations of 3,693 and 4,000 blocks, respectively. While the project is yet to report the amounts lost to the latest attack, Ethereum Classic is still extremely vulnerable to external interventions due to its low hash rate of approximately 2 terahashes per second. According to Crypto51, compared to Ethereum, the theoretical cost of a 51% attack on ETC is around 100 times lower, making the blockchain a potential target for malicious actors.

Bitfly, the parent company of Ethermine, reported the attack earlier this day in a separate tweet and notified that 7,000 blocks have been removed from their immature balance and all payouts will be checked. Other exchange platforms have also advised their users to take the required precautionary measures.


While the ETC community is taking steps to secure the blockchain and prevent further third-party interventions, major exchanges have warned the organisation that if the risk is not mitigated soon, the coin could face delisting. Ethereum Classic developers are actively working towards evaluating proposed solutions.

“ETC is ~3% of the overall ETH network hashrate. We are well aware of potential repeated attacks while solutions such as ‘reorg caps’ and the subsequent ECIPs are being tested and evaluated,” the organisation explained in a tweet. “If you haven’t already please increase (which most have) please [sic] raise confs above ~10K.”

Last week, ETC Labs, one of the leading organisations behind Ethereum Classic, announced its strategy to protect the network by using defensive mining, which is supposed to stabilize the plummeting hash rate and stave off further attacks.

The company is laying out a multi-stage roadmap to further secure the network, relying on closer coordination with exchanges, better network monitoring, and the implementation of a “Permapoint” finality arbitration system, a framework developed by the ETC Core Team to inhibit chain reorganisations and maintain consensus among nodes.

Show Comments