The Ethereum Classic (ETC) blockchain was hit with another 51% attack on Saturday evening — for the third time in a month.
The attack saw a reorganization of over 7,000 blocks, or around two days' worth of mining, according to Bitfly — the parent company of Ethermine mining pool. The Ethereum Classic organization confirmed the attack in a separate tweet.
The first and the second 51% attacks on ETC saw reorganizations of 3,693 and 4,000 blocks, respectively. In that sense, the third attack appears to be the largest, although the loss amount remains unclear.
ETC's hash rate remains low, which makes it vulnerable to 51% attacks. According to Crypto51, ETC's hash rate is 2 TH/s (terahashes per second), and the theoretical cost to 51% attack ETC is $4,860 per hour. The theoretical cost is the amount of money needed to rent hashrate for a particular time period. Ethereum's hash rate and the theoretical cost, on the other hand, is way higher than ETC, at 202 TH/s and $474,600 per hour, respectively, and thus makes it almost impossible to 51% attack the network.
The ETC community is taking steps to secure its blockchain. Earlier this month, ETC Labs proposed a multi-stage strategy to mitigate the risk of 51% attacks. If the community can't find a way to better protect the network, the coin could face delisting, major exchanges told The Block recently.