Last week unknown to the miners, obviously with significant capacity for mining algorithm Equihash, managed to expose the Bitcoin network Gold attack 51% and re-conduct a double-spend before the attack was noticed.
May 18, Director of communications at Bitcoin Gold Edward Iskra reported that the attacker exploits a vulnerability with the purpose of stealing funds from cryptocurrency exchanges.
For the attack the miner took more than 50% of the network hash rate yet, allowing him to temporarily control the creation of Bitcoin block Gold. Capture similar amount of computing power, even in such relatively small networks, like Bitcoin, Gold, entails considerable expense, since such actions can be monetized only through the double-spending transaction. Other advantages such attack does not.
The attacker started to send available BTG on cryptocurrency exchanges at the same time competing transaction after some time, sending them to a private wallet. Initially, the blockchain is only included the first transaction, but having some control over mining, the attacker is able to replace the last few blocks, eliminating thus the original transaction.
Thus, he was able to contribute to the exchange and withdraw them again, and then cancelled the original transaction and transfer the BTG on our own wallet. The attacker has accumulated a cryptocurrency in a separate address – now his balance is 388 201.92 BTG (about $18 million).
The last transaction was sent on may 18, but the attacker could theoretically resume the attack 51%.
The developers BTG
Yesterday evening the developers of Bitcoin Gold published a detailed explanation of the incident to the public, which says that such attacks may be subject to any inadequately protected cryptocurrency, which is associated with «some problems» technology of the blockchain.
They recommend exchanges to increase the number of required confirmations to 50 units to be credited BTG to the customer’s account.
«Ordinary users BTG is not at risk and any transactions with known partners are not a risk. The only real danger is the unconscious exchange directly with the attackers using very large amounts on the automated system. That is, for the exchanges,» according to the developers.
The team encourages the Bitcoin Gold exchange to cooperate, saying that carefully monitors the situation and informs them of the details, allowing you to quickly alert site in case of resumption of the attack.
To combat these problems, the developers of the Bitcoin Gold also reminded of the scheduled replacement of the hashing algorithm BTG at the end of June.
Interestingly, the theft of such large sums has not led to the collapse of the Bitcoin exchange rate Gold. This cryptocurrency has not lost positions in the market, slowly decreasing in relation to the Fiat with the others, but has not fallen relative to other cryptocurrencies. At the moment it is not known what exchange or exchanges suffered from the attack.