BitcoinABC vulnerability revealed

Not long ago, Bitcoin Cash forked, and the newly created blockchains are already facing potential problems. Shortly after the BSV blockchain (Bitcoin Cash fork from nChain) suffered a bug that split the network in two, the developers of BAB (BitcoinABC) released an update that puts the entire network at risk of a 51% attack.

The ABC blockchain previously relied on the classic Proof-of-Work algorithm, but the update introduced controversial “checkpoints” that are designed to protect against attacks in which attackers defraud the network.

The new ABC security model uses every tenth block mined as a sample to measure accuracy. If a miner sees a block on the network that does not match the ABC version of the blockchain stored at the checkpoint, he will automatically reject that block. 

However, this change may result in unwanted disclosure of transaction information as well as other network failures. According to systems analyst Eric Wall, if an attacker controls more than 50 percent of the ABC blockchain's total computing power (hashrate), they can fake block 10 by reorganizing the “real” blocks.

If a hacker launches an attack at the very moment the network finds block 10 and verifies it, the ABC blockchain will undergo a network split. This means that the ABC network is currently vulnerable to malicious forks.

According to experts, at the moment, a hacker can effectively control the ABC network using publicly available mining equipment worth $27,000. It is worth noting that if a hacker has access to just one Antminer S9, then after two years of secret mining, he could potentially become a real threat to the network.

By stopping the processing of transactions, the attacker could “freeze” the network, make changes to blocks, and also create opportunities for double spending.

The worst thing is that with just one (even not the largest) mining rig and just one evil intention, you can cause a lot of damage to the entire ABC network. 

According to thenextweb.com