Bitcoin cash (BCH) network experienced a hard fork on May 15, which brought some troubles for the network. As per a report released by the research arm of cryptocurrency, derivatives exchange BitMex on May 24, the network experienced two-block chain reorganization, resulting in a 3,392 BCH (about $1.35 million at press time) double spend.
The report further claims that BCH hard fork experienced three interrelated issues. For starters, right after the hard fork, a bug was evidently exploited by an attacker, wherein the attacker managed to “broadcast transactions which met the mempool validity conditions but failed the consensus checks.”
The miners who were mining to produce blocks with stated that empty blocks were produced. The miners became concerned over the issue and “may have tried to mine on the original non-hard fork chain, causing a consensus chainsplit.”
The third issue was that the consensus chainsplit purportedly prevented a system functioning that was meant to recover funds accidentally sent to SegWit addresses. As per BitMex Research, “[t]his failure may have resulted in a deliberate and coordinated 2 blockchain re-organization.” The report further claims:
“Based on our calculations, around 3,392 BCH may have been successfully double spent in an orchestrated transaction reversal. However, the only victim with respect to these double spent coins could have been the original ‘thief.’”
BitMex also reports that the above three issues during the hard fork have had resulted in 25 transactions (moving 3,392 BCH) not including the reorganized chain, which constitutes a double spend.