We can confirm that there was a successful 51% attack on Ethereum Classic
Some updates. Money stolen about $1.1m:<p>>exchange has since uncovered another 12 attacks that “included double spends, [now] totaling 219,500 ETC ($1.1 million) <a href="https://thenextweb.com/hardfork/2019/01/08/ehtereum-classic-51-percent-attack/" rel="nofollow">https://thenextweb.com/hardfork/2019/01/08/ehtereum-classic-...</a><p>Cost of attack according to <a href="https://www.crypto51.app/" rel="nofollow">https://www.crypto51.app/</a> about $5k