Worst nightmare for a blockchain – Although a 51% attack is unlikely on the Bitcoin network, they are unfortunately still common on smaller cryptosystems. The latest victim is GRIN, the „Anonymous Bitcoin“.
The GRIN attack at a glance
On Sunday, November 8, at first light, the 2Miners mining pool notified its customers that a 51% attack was underway on the GRIN network.
Shortly afterwards, the official GRIN website posted the following warning message:
„IMPORTANT: The GRIN network hash rate has increased dramatically in a short period of time. In particular, this coincides with the doubling of the NiceHash rate during this period, with more than 50% of the network hashrate currently outside of the known pools. Given these circumstances, it makes sense to wait for additional transaction confirmations before finalizing payments. »
In fact, an unknown pool suddenly began to mine GRIN. Unfortunately for the network, it armed itself with a colossal amount of hash power that allowed it to capture 58.1% of Grin’s hash power, making it the largest pool in the network.
Distribution of Grin’s chopping power by pool
The attacker’s intentions are unknown at the moment. Nevertheless, a reorganization was detected on a mined block on November 7, although no information regarding any double spending has been reported as yet.
The attack still appears to be ongoing at the time of writing.
NiceHash: the attackers‘ favorite tool
If you take a step back, this news is not extremely surprising. Indeed, the GRIN blockchain has a relatively limited chopping power. It costs only $76 per hour to rent the hash power needed to carry out an attack, as shown on the Crypto51 website, which references the 51% attack cost per blockchain.
In practice, attackers usually turn to NiceHash to conduct this type of attack. Indeed, NiceHash is a peer-to-peer hash power rental platform. It is extremely simple for an attacker to go there and rent the computing power needed for his attack.