A massive Bitcoin heist from December 2020 has just been exposed, making it the biggest crypto hack in history.

According to Arkham Intelligence, hackers stole 127,426 BTC from LuBian, a Chinese mining pool. The stolen Bitcoin was worth $3.5 billion at the time. Due to Bitcoin’s price surge, those assets are now valued at $14.5 billion.

LuBian Exploit Was the Biggest Crypto Hack in History

LuBian operated mining facilities in China and Iran. In 2020, it controlled almost 6% of Bitcoin’s total hash rate.

Arkham’s on-chain analysis found that over 90% of LuBian’s BTC was drained on December 28, 2020. Additional funds were stolen two days later from a Bitcoin Omni Layer address.

Neither LuBian nor the hacker publicly acknowledged the breach. The funds remained dormant until a consolidation event in July 2024.

Arkham researchers linked multiple addresses used in the theft and observed that each received OP_RETURN messages from LuBian. The pool spent 1.4 BTC across 1,516 transactions to appeal for the stolen funds.

This pattern strongly suggests the hack was real and not spoofed. The hacker has yet to move the stolen BTC again.

Arkham suspects LuBian used a flawed key generation algorithm, which may have exposed its private keys to brute-force attacks. LuBian still holds around 11,886 BTC worth $1.35 billion. 

Meanwhile, the hacker’s stash remains untouched, making them the 13th largest BTC holder globally.

This revelation surpasses the previous record—the $1.5 billion Bybit hack in February 2025.

Arkham’s disclosure adds new urgency to reviewing key security and crypto infrastructure, especially among legacy mining operations.