<p>The Ethereum Classic (ETC) blockchain was hit with another 51% attack on Saturday evening — for the third time in a month.</p> <p>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 <a href="https://twitter.com/eth_classic/status/1299824170260340737?s=20">confirmed</a> the attack in a separate tweet.</p> <p>The <a href="https://www.theblockcrypto.com/linked/73700/ethereum-classic-experiences-3693-block-long-reorg">first</a> and the <a href="https://www.theblockcrypto.com/linked/74130/ethereum-classic-another-51-attack">second</a> 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. </p> <p>ETC's hash rate remains low, which makes it vulnerable to 51% attacks. According to Crypto51, ETC's <a href="https://www.crypto51.app/">hash rate</a> 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.</p> <p>The ETC community is taking steps to secure its blockchain. Earlier this month, ETC Labs <a href="https://www.theblockcrypto.com/linked/75437/etc-labs-strategy-51-pct-attacks">proposed</a> a multi-stage strategy to mitigate the risk of 51% attacks. If the community can't find a way to better protect the network, <a href="https://www.theblockcrypto.com/daily/75117/crypto-exchanges-ethereum-classic-attacks?utm_source=newsletter&amp;utm_medium=email&amp;utm_campaign=2020-08-22">the coin could face delisting, major exchanges told The Block </a><a href="https://www.theblockcrypto.com/daily/75117/crypto-exchanges-ethereum-classic-attacks?utm_source=newsletter&amp;utm_medium=email&amp;utm_campaign=2020-08-22">recently</a>.</p>