Bitcoin holder claims hacker stole 139 BTC, paid record $3m in fees

A Bitcoin user assumed ownership of hacked funds involved in a record-breaking transaction where miner AntPool received over 83 BTC in fees.

An unknown X user claimed to be the victim of a hack connected to the largest Bitcoin (BTC) fee paid for a single transaction to date. On Nov. 24, an anonymous individual created the X page “@83_5BTC” and said their address paid 83.5 BTC in fees after creating a new cold wallet.

The user surmised that a hacker likely leveraged an automated script to hijack their transaction, paying a record fee worth an estimated $3.1 million in process.

crypto.news had reported the news a day prior, detailing 139.4 BTC sent in a transaction block mined by blockchain company AntPool.

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.

83_5BTC on X

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This user provided a signed on-chain message from the compromised Bitcoin wallet as proof of the claim. The text reads “@83_5BTC is the owner of the funds that paid the high fee” and was confirmed by Jameson Lopp, co-founder and CTO of Casa, a digital asset security provider.

Mononaut, the pseudonymous creator of Bitcoin explorer Mempool, also verified the claim. However, the signature may have been issued by the attacker or true victim, according to Mononaut who added that AntPool would have to rely on alternative methods of verification.

Furthermore, the developer explained how and why the hacker was able to steal cryptocurrencies from a Bitcoin wallet.

3/ The most likely explanation is that the wallet was generated from bad entropy – perhaps a brainwallet, or too few dice rolls/coin flips, or an insecure PRNG.

Let this be a reminder not to take shortcuts with your entropy, and ideally to use multisig for very large sums.

— mononaut (@mononautical) November 27, 2023

Until the incident on Nov. 23, crypto firm Paxos held the record for the biggest Bitcoin transaction fee. Paxos paid around $500,000 in an apparent “fat finger” error and miner F2Pool snapped up the fee. The BTC miner reportedly returned Paxos’ overpayment in a show of good faith.

It remained to be seen at press time whether AntPool intends to return the funds or how this crypto service provider plans to verify the self-proclaimed victim’s identity.

Read more: Bitcoin mining hits record high difficulty

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