The next attack
ZenCash was targeted for a 51 percent attack on June 3 at approximately 2:43 UTC, according to the official ZenCash blog. A 51% attack is when a malicious person or group takes control of a blockchain by gaining more than 50 percent of the hashrate, allowing the hacker (s) to take control of the network.
The ZenCash team began an analysis of the hashrate distribution to confirm that it is indeed a 51 percent attack. While the hash rate was being investigated, other team members contacted the exchanges at the same time to increase the confirmation times, thus minimizing the risk of double-spending. After the investigation was completed, the ZenCash team found that there were two duplicate transactions. This meant that the hacker was able to spend 19,000 ZenCash twice, doubling its value. Currently, 19,000 ZenCash are worth around $ 510,000.
The price of ZenCash fell right after the attack. Shortly after the hack, ZenCash had dropped from $ 30 to $ 28 and is now at $ 27. The Zen team will continue to monitor the network and conduct analysis with the affected exchange. All information collected will be made available to the competent authorities.
How could that happen?
With the increasing number of proof-of-work blockchains, it's becoming increasingly difficult to secure each one adequately, as some algorithms have hashed out hash performance.
The hacker has probably leased a large amount of hash through a service like NiceHash. Since the hacker got away with ZenCash worth over $ 550,000, it's safe to assume that the attack cost less.
The number of attacks has increased in the last month, with the most popular attacks on Verge, Bitcoin Gold and Electroneum. If a network is not backed up by a strong hash, such as Bitcoin, Ethereum, Litecoin, and ZCash, it is difficult for developers to fully protect the blockchain against a 51 percent attack.