Coinbase Reveals Ethereum Classic Chain Was Attacked
On Monday morning, Coinbase took to its official Twitter page to reveal that on Saturday, its internal developers detected a “deep chain reorganization” of the Ethereum Classic (ETC) blockchain.
On 1/5/2019, Coinbase detected a deep chain reorganization of the Ethereum Classic blockchain that included a double spend. In order to protect customer funds, we immediately paused movements of these funds on the ETC blockchain. Read more here: https://t.co/vCx89dz44m
– Coinbase (@coinbase) January 7, 2019
Mark Nesbitt, a security engineer at the world-renowned $8 billion startup, broke down Coinbase’s findings in a recent blog post. Nesbitt revealed that Ethereum Classic’s Proof of Work system, which runs on the ETHash algorithm, had fallen victim to “repeated” block “reorgs,” meaning that an unnamed attacker [group] managed to alter blockchain transactions repeatedly in recent memory.
Per data gathered by the firm, which is mandated to monitor the blockchains it supports, approximately 88,500 ETC has been double spent, a sum that amounts to $450,000 at their transaction time. Citing data from Minergate, Nesbitt broke each reorg down one-by-one, doing his utmost to find the extent of each individual attack.
The first two attacks, which came on Saturday, were innocuous enough, as no overt double spends were detected. Interestingly, the second attack was “highly suspicious,” but considering that no ETC was double spent, no red flags were triggered. Yet, as the third attack hit on Sunday, Coinbase shut down its “interaction with the ETC blockchain,” as ETC was double spent. Over the hundreds of blocks that followed, thousands of ETC was double spent.