A user who paid $3.1 million in fees became a victim of a hacker

User under the nickname 83_5BTC, with addresses who was paid a record commission of $3.1 million on November 23, said he was the victim of a hacker.

It was my BTC that paid the high fee.

I created a new cold wallet, transferred 139BTC to it and it got transferred out to another wallet immediately. 😵

I can only imagine that someone was running a script on that wallet and that the script had a weird fee calculation. ☹️

— Hackers_paid_83.5BTC_fee_with_my_money (@83_5BTC) November 24, 2023

According to him, the attacker stole more than 139 BTC ($5.2 million), including transaction costs of 83.65 BTC ($3.1 million).

To prove his words, 83_5BTC signed a message from the specified Bitcoin address: “@83_5BTC is the owner of funds that paid a high commission.” The signature was verified by Mononaut, the developer of the Mempool tool.

Casa co-founder and CTO Jameson Lopp also confirmed the signature.

However, since the wallet is compromised, this signature could very likely have been created by a hacker.

Community member niftydev stated that he knows the person behind the 83_5BTC account and he is not an attacker.

Representatives of AntPool, who verified the transaction, did not comment on the situation.

According to Mononaut, the most likely reason for the hack was the low entropy of the victim’s wallet, which made it vulnerable.

In this case, several attackers could compete to steal funds and increase the commission in order to speed up the withdrawal of funds to their address, the expert added.

Mononaut also noted that the fee paid was exactly 60% of the total 139.42 BTC stolen, and the would-be hacker stole an additional 0.001 BTC from the same address, paying 0.0006 BTC in fees.

On September 10, blockchain infrastructure company Rahos mistakenly paid 19.82 BTC ($510,750) as a fee to miners for transferring 0.074 BTC (~$1800).

Representatives of F2Pool reported that after the necessary checks, they returned the company’s bitcoins.