Hackers have just stolen $ 1 million from the Ethereum Classic blockchain in a rare "51%" attack

An attack on the Ethereum Classic blockchain may have helped hackers steal about $ 1.1 million in currency from other users, according to the popular Coinbase cryptocurrency exchange.

Ethereum what? Ethereum Classic is the original blockchain of Ethereum. In 2016, to counter another type of attack, the developers of Ethereum have created a new version of the transaction history that returned $ 50 million of cryptocurrency that was stolen by a hacker. Not everyone has passed, however, and those who have continued to use the old blockchain make up the Ethereum Classic community. Its market capitalization is about $ 500 million, compared to the $ 15.5 billion Ethereum. Coinbase started listing the Ethereum Classic token in August.

Are not blockchains blocked? Not exactly. Bitcoin, Ethereum, Ethereum Classic and similar blockchain networks are vulnerable to an attack where a "miner" controls over 50% of the network's computing capacity. This theoretically provides an opening to defraud other users by paying them in cryptocurrency before creating an alternative version of the blockchain in which the payment never happens, eventually making the alternative version the authoritative blockchain. This is what Coinbase says in this case. (see: "How safe is blockchain, really?")

And now? Coinbase says that he "interrupted interactions" with the compromised blockchain immediately when he noticed the Saturday problem. Kraken also suspended trade. In the meantime, those who manage the Ethereum Classic Twitter feed I asked exchanges to "substantially increase" the amount of time they spend to confirm new sets of transactions. Probably there is still much more in this story.