A fake job interview led to a coding assignment. The assignment led to a compromised work computer. Weeks later, attackers used that computer and an internal AI tool to reach two more engineers, and from there Binance's wallet operations.
That is the sequence Binance describes in its findings on the October 29, 2026 attack on the exchange. Binance says about $6.34 billion in digital assets were affected. The next largest crypto theft on record, the roughly $1.5 billion taken from Bybit in February 2025, was about a quarter of that. 12
What was affected, frozen and lost
Three numbers answer three different questions:
- Affected: about $6.34 billion. That is what Binance says the attacker moved or had access to.
- Frozen or intercepted: about $2.85 billion. Binance says this figure is subject to reconciliation and price swings.
- Finally lost: not yet settled. Binance says it has reserved more than the funds needed to cover the loss and will absorb the cost, and that by October 31 it had replenished 98% of the impacted token assets. It is buying the remaining, less liquid assets. 1
So the headline is a claim about the size of the theft, not about what customers or the exchange ended up losing. On the amount taken, no other crypto theft I could find comes close; the figure may still be revised.
The attribution has two sides. Binance says the FBI's latest information indicates North Korea is responsible. North Korea denied involvement. 13
How it unfolded
- June 2026: A wallet engineer ("Engineer A") downloaded a tampered installation of Homebrew, a developer package manager, while looking for an AI coding tool. Binance says it detected this, replaced the device and rotated credentials.
- September 2026: Another engineer ("Engineer B") was approached on a job platform. After rounds of fake interviews, including a video call with a fake HR representative and a second round with someone posing as a CEO, he was told to download a coding assignment onto his work computer. Binance says it contained malicious code that ran during setup and swapped a legitimate pyenv component for a malicious one.
- October 20: The attacker used Engineer B's computer and an internal AI tool to gain control over Engineer A and a third engineer ("Engineer C"). On Engineer A's computer they found a token that allowed deploying containers, which are packaged environments for running software.
- October 29, about 17:15 to 19:56 UTC: Using credentials stolen from Engineer A, the attacker logged into Engineer C's computer, deployed a container and ran an attack script. Around 20:05 UTC, hot wallets began sending funds out, starting with 233.46 million XRP to one address. 1
The attack did not need one person to hold every key. It collected small footholds and used each to reach the next.
What the AI tool did, and what we don't know
Binance's sentence is brief: the attacker "used an internal AI tool to gain control over" two engineers. It does not say "their computers," and it does not describe how the tool was used. 1
What the disclosure supports: an internal AI tool was one link between a compromised computer and other staff. What it does not say: that a model planned or carried out the theft, or that a particular prompt-injection technique was involved. Binance says it has rebuilt the tool along with the wallet system.
The general lesson holds either way. An internal assistant is useful because it can reach tools, data and people. If those connections are too broad, whoever gets into it inherits that reach.
Why it was hard to stop
Binance says the attacker also used the Ethereum feature EIP-7702, which lets a wallet delegate its actions to a smart contract, to give an attacker-controlled contract partial control over a hot wallet. Binance's wallet used multi-party computation, so no single key could cancel the delegations at once, and suspending withdrawals did not invalidate them on the blockchain. Binance had to build a special revocation procedure and cleared the delegation on October 30. 1
The employee who opened the assignment is not the whole explanation. The question is what each connected tool could reach after the first compromise, and which boundary should have stopped the next step.
References
- Initial Findings and Response Update. (n.d.). https://www.binance.com/en/blog/community/3229153443759566763
- Hackers steal $1.5 billion from exchange Bybit in biggest-ever crypto heist. (n.d.). https://www.nbcnews.com/tech/crypto/hackers-steal-15-billion-exchange-bybit-biggest-ever-crypto-heist-rcna193273
- North Korea denies involvement in Binance hack. (n.d.). https://apnews.com/article/01c9b80d938dd67c747e268c410f265d