Calin Culianu, a Bitcoin Cash developer who works on the Electron Cash wallet, has recently fired back against the hackers who exploited a bug in the Bitcoin Cash blockchain to get miners to find empty blocks right after its scheduled May 15 hard fork.
Speaking to CoinSpice, Culianu revealed that right after he saw the attack was occurring and that the BCH blockchain wasn’t processing transactions, he “panicked” and “thought it was the end of the world.”
Right after Bitcoin ABC developers deployed a patch that fixed the bug and things got back to normal, he claims to have realized it was possible to get back at the attackers. As such, he got together with other developers to collect information, and soon realized the attackers “didn’t use crypto keys to secure their funds.”
BCH came under attack today, due to an old bug in block template creation. Attack led to empty blocks for a short while, until patched, otherwise had little effect.
— Emin Gün Sirer (@el33th4xor) May 15, 2019
After digging through block explorers to figure out the attackers’ addresses, the developers claim to have been able to collect over 1.2 BCH (around $470) from the attackers in over 3,000 transactions. The funds, he claims, will be split with his “accomplices.”
To liquidate the attackers’ addresses, Culianu explained he remembers seeing they made “some funny transactions” to trigger the bug. After looking at data from these transactions, he told the news outlet some patterns “specify how to spend it.” Referring to these patterns, he said:
It’s Bitcoin Op Code, which lacks a signature … some garbage they used to attack the BCH network. Anyone can make one of those because it’s not cryptographically secure, and then redeem all their funds.
On Reddit, he bragged about his accomplishment, and received various tips from the cryptocurrency’s community for managing to get back at the attacker. Culianu noted that he believes there are other BCH wallets he didn’t get to without cryptographic keys guarding them, and estimates nearly 3 BCH ($1,200) are still up for grabs.