51 Persen Attack, ZenCash

ZenCash is the latest victim of a 51 percent attack that has been a scourge in the Blockchain sector. This privacy-focused Altcoins joins the list of other crypto-attacked currencies 51 percent in recent times, such as Bitcoin Gold, Eletroneum, and Verge.

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About 51 Percent Attacks

For those of you who do not know, 51 percent attacks occur after the hacker secures or controls most of the network hashrate (at least 51%). Once secured, an attacker can confirm a cheat block and perform a "double expense". Two expenses made can store digital tokens on the exchange and confirm the transaction to the hacker wallet simultaneously.

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In addition, hackers can use Blockchain to have the majority consensus from the network, as well as to reverse transactions from the exchange to separate purses. This proves to be a very profitable venture and can generate millions of dollars. In this ZenCash attack, it was reported that a total of 23,152 ZEN were made from exploitation and worth about $700,000.

Chronology Of Attack 51 Percent ZenCash

According to an official statement issued by ZenCash (ZEN), fraudulent miners launched an attack on June 2, 2018. However, the company immediately implemented a mitigation procedure to increase the difficulty of future network attacks. Here's the chronology of the event:

• (June 2, 2018, 20:26 EDT) - Operator Pool warns ZEN of a potential 51 percent offensive.
• (June 2, 2018, 20:34 EDT) - ZEN developers launch an investigation and evaluate the distribution of hash power. At the same time, the exchange sends a notification about the increase in confirmation time.
• (June 2nd 2018, 20:42 EDT) - The investigation results confirm that a suspected transaction is a double expense.
• (June 3, 2018, 09:00 EDT) - ZEN issued an official statement about a 51 percent attack on its krypton.
• (June 6, 2018, 09:46 EDT) - Rob Viglione, founder of ZEN, began to try to overcome the attacks to cope with negative impacts.

Attack Source Already Found

At the time of the incident, ZEN network hash level reached 58MSol per second. Thus, it is believed that the hacker is a large organization with enough mining power to execute an attack. ZEN reveals the suspect pool address in their statement. The attack appears to be from the Wallet address "znkMXdwwxvPp9jNoSjukAbBHjCShQ8ZaLib", and occurs between blocks 318165 and 318275. In addition, some "reorganizations" of Blockchain are also perpetrated by attackers, and they execute multiple expenditures between blocks 318204 and 318234.

To eliminate ZEN-related concerns, the company said, "The 100x increase of confirmation (transactions) makes a 51 percent offensive unlikely.ZenCash remains committed to ensuring the security of customer funds."

reference :
https://btcmanager.com/privacy-centric-zencash-latest-in-line-to-suffer-51-percent-attack/
https://cryptodaily.co.uk/2018/06/zencash-hit-by-double-spend-attack/