Cronos confirmed this Tuesday (8) that its validators discarded 10,961 blocks, equivalent to 1 hour and 54 minutes of history, to restore the network to the state prior to an attack against the Tectonic lending protocol. The measure reversed approximately US$ 111.2 million of the US$ 120.4 million involved in the incident.
The rollback did not affect only the attacker's operations. All transactions recorded during the discarded period were reversed, including transactions unrelated to the attack. The network returned to block 90,896,188, the last block prior to the exploit, after being interrupted at block 90,907,150.
The decision highlights the ability of validators to alter the history considered definitive by the blockchain in an emergency situation. In the post-incident report, Cronos stated that it needed to weigh the finalization of transactions expected by users against the risk of leaving assets under the attacker's control.
Exploit reached US$ 120.4 million at Tectonic
The attack occurred on August 30 and targeted Tectonic. According to Cronos, the attacker manipulated the price of TONIC, the protocol's governance token, and used the artificially elevated value as collateral to take out loans in nine markets. The total reached US$ 120.4 million before the network halt.
The reversal was able to neutralize most of the operations because approximately 92% of the affected value was still within Cronos when the blockchain was halted. Another US$ 9.19 million, or 7.6% of the total, had already left the network and remain outside the reach of the rollback.
Block production resumed about 11 hours after the start of the attack, with balances restored to the state prior to the exploit. Cronos said it continues to work with exchanges, bridges and other platforms to reconcile transactions affected by the change in history. Users do not need to take any action at this time.
