An anomaly in the Bitcoin network helped an investor to spend his coins twice

One transfer between wallets was counted twice due to a conflict between miners. As a result, the blockchain of the first cryptocurrency split into two chains.

The Bitcoin network crashed for a negligible amount. The research department of the derivative platform BitMEX Research reported that yesterday, January 20, a double spend was discovered on the blockchain of the cryptocurrency at block 666833 – one transaction for transferring 0.00062063 BTC was counted twice. At the current exchange rate, this is about $ 21.

The researchers explained that at block 666833, there was a conflict between the two mining pools SlushPool and F2Pool. As a result, two chains of blocks were formed. One of them recorded a transfer to 0.00062063 BTC to wallet 1D6aebVY5DbS1v7rNTnX2xeYcfWM3os1va. In another, the transfer amount was also 0.00062063 BTC, but only 0.00014499 BTC reached the recipient, the rest was spent on commission.

“Looks like a small double spend was discovered … 0.00062063 BTC was sent on the same chain. In the other chain, the same amount of coins were spent, but only 0.00014499 BTC were spent, ”the analysts wrote. In the conflict of mining pools, SlushPool won, since the block chain he found turned out to be longer than the competitor’s chain, BitMEX specified. Thus, on the bitcoin network, only a transfer of 0.00014499 BTC is considered valid. The second transaction for 0.00062063 BTC is considered invalid.

This is confirmed by the data of the blockchain explorer The service displays information on the transaction for 0.00014499 BTC correctly. If you check the transaction for 0.00062063 BTC, then the browser shows this transaction as invalid. Later, BitMEX researchers wrote on their Twitter account that a replace-by-fee (RBF) attack could be the cause of the incident. It is about manipulation, where an attacker tries to gain access to a cryptocurrency wallet by intercepting the sender’s transaction by paying a higher fee.

A double spend is a situation when a random user or attacker manages to spend the same amount twice. For example, send 1 BTC twice between wallets, as a result of which two coins will come to the final address. A similar thing happened in August on the Ethereum classiс network. Then the unknown made two “51% attacks” on the altcoin blockchain. During the first, he applied the principle of double spending and, having doubled the original amount of ETC, embezzled $ 5.6 million.

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