Criminals who used cryptocurrency mining to perform a 51% attack on smaller coins, managed to steal at least 19.5 million dollars this year. These attacks, five in total, took place between April and June. This was reported by security firm Group-IB to The Next Web.
During a 51% attack one group or person gets access to 51% of the mining power on the network. They are then able to alter the blockchain and steal lots of coins.
To gain 51% of the mining power, you need a lot of computer power. To perform such an attack on the Bitcoin network, it would cost close to 390 thousand dollars for one hour according to Crypto 51. With Ethereum the costs would be around 148 thousand dollars.
For that reason hackers who perform a 51% attack, generally aim at smaller coins. Verge (XVG) has been hit twice. In April one million dollars was stolen after a bug was exploited. In May a similar attack happened again. ZenCash, now known as Horizen (ZEN), saw 550 thousand dollars worth of ZEN stolen, while Litecoin Cash was also hit.
The biggest 51% attack took place on the Bitcoin Gold (BTG) network. Hackers managed to steal 18 million dollars worth of BTG back in May. As a result Bittrex removed the coin from its exchange. The team behind BTG performed a hardfork to undo and devalue to stolen coins.
A college freshman who goes by the name of ‘geocold51’ is a crypto enthusiast and cyber security researcher who’s out to show that 51% attacks are way too easy to perform. Live on Twitch and other streaming platforms he showed how easy it was to do a 51% attack on Bitcoin Private. He managed to double send coins from one of his wallets to two other wallets.
Geocold51 only does these attacks to test and make people aware of the ease of these actions. For 200 hundred dollars he can use cloud mining services to perform his attack. If he would’ve needed the hardware, the costs would be around 100 thousand dollars.
According to the website Crypto 51 an attack on Bitcoin Private (BTCP) would cost $79, while PACcoin (PAC) would be even a cheaper target with a price tag of $58. The cheapest coins to attack are Einsteinium (EMC2) with 17 dollars, FlorinCoin (FLO) $15 and Bulwark (BWK) with only 5 dollars in costs for a 51% attack.