Privacy coin ZenCash (ZEN) has become the latest altcoin to succumb to a 51 percent attack, the project’s developers confirmed over the weekend.

According to an official statement, a malicious miner successfully executed the attack — as well as at least two double spends — against the cryptocurrency’s network on June 2 at approximately 10:43 pm ET.

To deploy a 51 percent attack, an attacker must acquire a majority of a cryptocurrency network’s total hashrate, which provides them with the ability to reorganize the blockchain and force it to accepting fraudulent blocks.

Typically, an attacker will monetize a 51 percent attack through a double spend attack. This is accomplished by depositing coins at a cryptocurrency exchange while also signing a transaction that sends the same coins to an exchange and then selling for another cryptocurrency.

Meanwhile, the attacker uses their majority hashpower to mine a fork of the main blockchain that quickly grows longer than the one accepted by the network. This allows them to reverse the transaction that first deposited their coins at the exchange and instead move the funds to another wallet in their control.

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In this specific case, the attacker executed at least two double spends, including one that reorganized the blockchain by a full 38 blocks. Altogether, the attacker made off with ~$550,000 from this attack.

Many networks have hit recently by 51 percent attacks in recent weeks, including Bitcoin Gold, Monacoin, and Verge (at least twice). The cost to launch a 51 percent attack against many altcoin networks is shockingly low, especially since hashpower can easily be rented from the open marketplace.

What do you think of the recent 51% attacks happening in the cryptocurrency market?