At night ZenCash underwent a 4-hour "51% attack". The hacker managed to roll back 38 transactions and steal $ 550 thousand before the mining pools managed to inform the developer, and that one- the exchangers. According to the 51Crypto service, which uses a public algorithm to calculate the cost of attacks, the organization of the attack costed only $ 30 thousand.
This is the 6th "51%" attack on cryptocurrencies over the past 2 months. Earlier, Bitcoin Gold ($ 18.6 million), Verge (twice $ 1.76 million and $ 0.8 million), Monacoin ($ 90,000 loss) and Electroneum (claim there was no damage) were attacked earlier. The high vulnerability of all PoW-cryptocurrencies was repeatedly warned by Bitcoin developers Jameson Lopp and Peter Todd.
At one time, the developers proceeded from the assumption that it would be economically unprofitable for miners to make "51% attacks". However, these expectations turned out to be too idealistic, and now developers will have to spend part of the profits to protect digital assets