A Coinbase engineer estimated that an attacker managed to double-spend more than US$100,000 on the ASIC-resistant Vertcoin blockchain this past month.
Vertcoin’s blockchain—designed to prevent network centralization by only one group of cryptocurrency miners—fell victim to multiple 51-percent attacks in the previous weeks.
In a Medium post, Mark Nesbitt pointed out at least four incidents of double-spending made possible by 51-percent attacks on the Vertcoin network.
The first incident was recorded on October 12, with the latest happened on November 29. The attacker managed to double-spend coins worth over US$100,000.
Nesbitt, a security engineer at crypto exchange Coinbase, wrote:
“We observed repeated deep reorganizations of the Vertcoin blockchain, with the latest reorg having a depth of 307 blocks and a length of 310 blocks. The total value of the double spends was over $100,000.”
In double-spending, a malicious attacker could spend his crypto twice in two different transactions. This could be possible—among other possible means—through a 51-percent attack, in which the attackers control the majority mining power of the blockchain and, in turn, control the behavior of the network.
The Vertcoin blockchain was meant to be resistant to the powerful ASIC (application-specific integrated circuit) mining rigs and was specialized for GPU/CPU mining, all thanks to the network’s Lyra2Rev2 algorithm.
However, developers have managed to develop new ASICs that could bypass Vertcoin’s restrictions. And these ASICs could have taken part in the recent 51-percent attacks on the network.
As a response, the Vertcoin Development team would fork the blockchain in the near future to implement the new Lyra2REV3 algorithm that would “brick existing ASICs,” among other features.