Bitcoin Gold hit by Malicious Miner`s Double Spend Attack

An evil-minded miner efficiently made a double spend attack on the Bitcoin Gold network, making BTG at least the third altcoin to succumb to a network attack
23 May 2018   815

Edward Iskra, Bitcoin Gold director of communications first admonished clients about the attack on May 18, reporting that an evil-minded miner was using the exploit to steal means from cryptocurrency exchanges.The miner bought at least 51 percent of the network’s total hashpower, which provided them with temporary control of the blockchain. Gaining this much hashpower is extremely expensive — even on a smaller network like bitcoin gold — but it may be monetized in tandem with a double spend attack.

The attacker, after getting the control of the network, started depositing BTG at crypto  exchanges while also intending to send those same coins to a wallet under their control. Generally, the blockchain would resolve this by including only the first transaction in the block, but the attacker managed to reverse transactions as they had majority control of the network.

As a result, they were able to invest funds on exchanges and withdraw them again soon, after which they repealed the initial transaction. This way they could send the coins they had primarily deposited to another wallet. 

An address of bitcoin gold connected with the attack has got more than 388,200 BTG since May 16 (basically from transactions it sent to itself). All of those transactions were associated with the double spend exploit, the attacker could have stolen as much as $18.6 million worth of funds from exchanges. The last transaction was sent on May 18, but the attacker could resume it if they still have access to enough hashpower to reach the control of the blockchain.

Bitcoin gold’s developers recommended exchanges to resist the attack by reaching the number of confirmations acquired before they lended deposits to client accounts. Blockchain data displays that the attacker reversed transactions as far back as 22 blocks, allowing developers to advise raising confirmation requirements to 50 blocks.

Bitcoin Gold Hardfork to be Implemented

Modified Equihash-BTG algorithm was launched on block 536200
05 July 2018   392

On block 536200 Bitcoin Gold network was transferred to the modified Equihash-BTG algorithm, not supported by classic ASIC-miners. This is the developers of crypto-currencies reported in the official blog.

Thus, the project promotes one of its main ideas, which consists in avoiding ASIC-mining.

According to the developers, the new algorithm includes personalization, which makes it difficult to redirect the power of mining through the markets of hashing capacities, which guarantees greater network security.

Also in the course of the hack, an improved difficulty adjustment algorithm (LWMA) was added, which will allow BTG to work faster, providing a more stable flow of blocks.

We thank them all for their hard work in recent days getting ready for this upgrade… and for dealing graciously with the few snags and hurdles that will inevitably come after an important Upgrade like this.

We know that this milestone isn’t an endpoint… it’s just a waypoint we pass along the way to better things. First, we’ll make sure everything continues to function as expected, and we’ll help the inevitable stragglers get on board with the new code… and then we have a whole bunch of new things we’re looking forward to sharing with the Community!
 

The Bitcoin Gold Organization

In early June, the Bitcoin Gold team said that updating the network will make the cryptocurrency less vulnerable to various hacker attacks. In May, an unknown miner, through a "51% attack" on the BTG network, stole about 388,000 coins from the exchanges.