ZenCash 51 percent attack and double spents

ZenCash network was hit with 51 percent attack yesterday, on June 2nd 2018 at 0243H UTC. The ZenCash team did mitigation steps to increase the difficulty of future attack on its network and safeguarded its network. However, around 6600 ZEN and 13000 ZEN for double spends were done and attacker was able to reorganize more than 30 blocks. This means the attacker knew what he was doing.

ZenCash team says that it will continue to monitor the network and do forensic analysis on the exchanges that are affected with it.

In little less than a month, three big cryptocurrencies that make use of PoW algorithms have been attacked using 51% method. This includes Bitcoin Gold, Verge and now, ZenCash. That being said, algorithm leaders such as BTC, LTC, XMR, ZEC are fine. Other PoW coins are exposed to 51% attack, any minute.

Here are details of the double spend:

1st Double Spend – 6,600 ZEN

Orphaned transaction
https://explorer.zensystem.io/tx/574255141dd0b7c89e339e96ff46af818dcb298311ec13660eaf621d5b8f4f84
In orphaned block
https://explorer.zensystem.io/block/000000006be2c36df986223a4d37a520d1028e0db85db9277d9b14e811d243f3
Double-spend transaction
https://explorer.zensystem.io/tx/60b6555144530a0dce591ad7121a99464454821a25bb2ae3464c2ea6d2274003
Included in attacker block
https://explorer.zensystem.io/block/000000002e501b0a74eeae80091eddea52c8cd0f677f6de13abe0420af8397d9

2nd Double Spend – 13,000 ZEN

Orphaned transaction
https://explorer.zensystem.io/tx/1fdca015076dc3578a06f0cee0a6b97f9993a129bb4559289c94a56e5ea618cf
In orphaned block
https://explorer.zensystem.io/block/00000000129b387f2980e70a8c7ba90eda0bb674a2cd197a0edb1aefa723f62c
Double-spend transaction
https://explorer.zensystem.io/tx/17c14153004c701b4986fa1368fb9b2711953723d696258f451786b91c8dfa46
Included in attacker block https://explorer.zensystem.io/block/000000003b6cc6af447c4a422dd41b306211f9fc2990c744bae55c42df2a3b28