In the period from May 13 to May 15, the Japanese Monacoin cryptocurrency was affected by a network attack, which resulted in damage of $ 90,000. This is reported by CCN.
The publication believes that this was a mining attack when one miner successfully mines the block on the blockchain but does not transfer the new block to other miners. If he finds the second block, before the others find any new blocks, then he can create a new longer chain of blocks in the Monacoin network. When he makes his longer chain public, he will annihilate all the blocks discovered by other miners at a time when the secret chain was hidden.
The attacker tried to send Monacoin to exchanges outside of Japan, such as Livecoin, to exchange them for other currencies before the hidden chains were discovered. Miner, who is still unknown, had sufficient processing power to receive 57% of the hashpower at one point in order to perform this attack.
The official Monacoin page on Twitter says that the project team knows about the attack. But since then, there has not been a clear statement of the proposed solutions. However, other sources indicate that developers are currently working with stock exchanges on the Monacoin blockchain rollback plan to the point preceding the attack.
— monacoinproject (@tcejorpniocanom) May 17, 2018