First it happened to verge. $1.8m of cryptocurrency swiped in a matter of hours. Then to bitcoin gold, plundered in an $18m double spend attack. Then to verge again, this time to the tune of $1.7 million. Along the way, monacoin is also believed to have been hit. Someone is methodically working their way through Proof of Work coins, controlling their hashrate, and then launching 51% attacks. Other PoW teams are now on high alert for signs that their coin could be next.
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Following a Spate of Attacks, PoW Teams Batten Down the Hatches
51% attacks, in which a malevolent miner controls the majority of the network hashrate and then uses it to force through fraudulent transactions, are commonly discussed but rarely encountered. That all changed on April 4 when verge was hit by a 51% attack. At the time, the incident was put down to the general fog of incompetence that surrounds verge; the exploit was quickly patched and everyone moved on. Then, just over a month later, verge was hit again along with bitcoin gold and possibly monacoin too. The spate of attacks has caused a crisis of confidence in Proof of Work coins and forced their development teams on the defensive.
Although called a 51% attack, in reality it’s often possible to control the network with a much lower hashrate. Because verge uses five different hashing algorithms, for example, the attacker was able to reduce the mining difficulty for just one algorithm and focus all their firepower on that, armed with just one fifth of the hashpower they would otherwise have needed. The second time around, they modified their attack slightly and targeted verge with
