Yesterday (Sunday, February 25) at 22:00 UTC an attack attempt started on the network, considerably increasing the hashrate of it.
Upon realizing, we performed the routine procedure checking the stability of the official nodes and performing certain synchronization tests, the results:
1- The bootnodes were correctly synchronized.
2- Public RPC nodes synchronized correctly.
However, there was a reorganization that caused some third-party nodes to be synchronized with an obsolete version of the chain, generating small losses, especially in mining pools.
Approximately one hour later some of the nodes returned to normality by integrating to the correct chain. At the time of this public statement, the network is completely stable.
We will continue to investigate this. We already have personal data of the possible attacker and we will begin to take actions against him. For now, we recommend all services to increase the number of confirmations for each transaction to 300 before crediting it.
We want to thank everyone on the team for the hard work and for being tracking everything during this event.
Special thanks to Stex and HitBTC for taking actions on this matter to prevent loses from the users and from Callisto Network.
Special thanks to MaxHash pool operator for helping and advising about this matter.
Special thanks to the pools that managed this issue with professionalism.
The solution for this kind of attacks is going to be implemented soon. We were already working on this and we are close to putting an end to these issues.