A Bitcoin user says they were the victim of a hack which resulted in over $3 million in fees paid to process a transaction last week. The self-described victim claims 139 BTC, worth $5.2 million, was stolen from their wallet and quickly sent to another address.

After creating a new Twitter account "@83_5BTC", the user signed a verified message from the associated wallet address stating they controlled the key. But security experts note the wallet may still be compromised allowing an attacker to also sign.

According to analysis, the likely cause was a vulnerability stemming from a Bitcoin wallet created with insufficient randomness. This opened the door for scripts automatically configured to steal funds and pay exorbitant fees to outpace other hackers.

The record $3.1 million charge replaced an initial 51% transaction fee likely from a separate attack. AntPool, which processed the block, has not commented. But if the victim can further verify identity, the mining pool could reimburse the fee as done previously.