Proof-of-Work tech under fire after 51% attacks on Electroneum and Verge

Two cryptocurrencies have recently become victims of the dreaded ‘51 percent attacks’ on their blockchains.  Electroneum suffered a 51 percent attack which was discovered when it was noticed that a massive amount of empty blocks were being constantly mined on the currency’s blockchain one after another, preceded by a sudden drop in hashrate.

Following the Electroneum attack it was reported that Verge’s blockchain had also been compromised by a 51 percent attack. Around 250,000 XVG were stolen by the attacker, as the attacker was able to mine multiple blocks one second apart using the same (scrypt) algorithm. This feat would have had been impossible if not for the bugs that existed in the code of Verge’s blockchain, as pointed out by the BitcoinTalk user ocminer.

The blocks were all mined subsequently one second after the other; the 90 mins difference seen is the bug the miner exploited to make this happen.