Yet another altcoin succumbed to a malicious mining attack. BTC Gold (BTG) reportedly fell victim to a double spend attack when a miner gained 51 percent control of the network, making it the third altcoin to suffer losses from such kind of attack in the last couple of days.

Records showed that the miner managed to access more than half of BTC Gold’s hash power, enabling them to temporarily take control of the altcoin’s blockchain. After gaining access to the network, the miner started depositingBTG coins at several cryptocurrency exchanges, and then quickly withdrew the coins, which he sent to another wallet.

According to reports, the miner successfully reversed transaction as far back as 22 blocks. This prompted BTG developers to issue a statement advising exchanges to increase the number of confirmations required by an account owner before the exchange can deposit funds into their account, as well as suggesting that confirmation requirements be raised to 50 blocks to reduce future attacks from happening.

The BTC Gold address used for the attack received more than 388,200 BTG from May 16-18. BTC Gold director of communications Edward Iskra confirmed the attack on the altcoin network’s forum, warning its users to be “aware of any transaction related to the above known attacker’s addresses.”

“It’s important to protect the ecosystem. This is a real threat. We don’t want anyone lose money,” Iskra wrote.

A closer look at the account revealedit made self-transactions sending money to itself.Transactions made on the account resultedin about $18.6 million loss, although it’s unclear whether the amount in the account was all from the double spend exploit.

BTG is a project led by Jack Liao of Hong Kong mining firm Lightning ASIC seeking to change the proof-of-work (PoW) algorithm and promising to enable common people to mine using ubiquitous, low-cost graphics cards. It’s worth noting, however, that this accessibility means attacking the system will also be cheap—which Dr. Craig Wright, chief scientist of the nChain Group, has previously pointed out.

BTG is the third altcoin to suffer from a malicious mining attack in recent days. Verge had two hacks within a span of two months losing about $2.8 million. The attack on Monacoin, a Japanese cryptocurrency, led to about $90,000  loss when a hacker managed to gain 57% control of its system.

Note: Tokens on the Bitcoin Core (segwit) Chain are Referred to as BTC coins. Bitcoin Cash (BCH) is today the only Bitcoin implementation that follows Satoshi Nakamoto’s original whitepaper for Peer to Peer Electronic Cash. Bitcoin BCH is the only major public blockchain that maintains the original vision for Bitcoin as fast, frictionless, electronic cash.