Index card. Binance says about $6.34 billion was taken on 29 Oct after attackers spent five months moving from a tampered installer to a fake job interview to its own internal AI tool, and finally into its wallet signing service. About $2.85 billion is frozen or intercepted, and the FBI blames North Korea. Why was one stolen deployment token enough?
The keys never leaked.
They didn’t need to.
Binance published its first findings on the hack at 14:33 UTC on Tuesday, in an article on X titled “Initial Findings and Response Update”.
It opens with an apology: “This should not have happened.”
The status, in Binance’s words and numbers: about $6.34 billion in digital assets were “impacted”, and about $2.85 billion has been frozen or intercepted, “subject to reconciliation and market price volatility”.
The theft hit at least five networks: XRP Ledger, Solana, Optimism, Bitcoin and Ethereum.
The exchange says it will absorb the loss, has set aside more than 100% of what is needed, and had replenished 98% of the affected token assets as of 31 Oct.
Attribution rests with the FBI, which named North Korea on 31 Oct. Binance cites that finding. It has not added an attribution of its own.
This is an initial report. Binance says some technical details will stay confidential and that independent security firms will review its findings.
So the Binance hack findings answer one question and open another.
How did an outsider end up holding the signing pen?
The Binance hack findings, minute by minute
All times below are UTC and come from Binance’s report unless another source is named.
29 Oct, 17:15. The attacker logged on to the computer of a wallet software engineer Binance calls Engineer C.
17:15 to 19:56. Using credentials taken from a second engineer, Engineer A in Wallet DevOps, the attacker deployed a container and triggered a malicious script.
20:05 to 20:09. 233.46 million XRP left five Binance hot wallets for an attacker-controlled address. A hot wallet is the internet-connected wallet an exchange uses to pay out withdrawals.
Next. Hot wallets on Solana and Optimism sent about 970,500 SOL and 44.2 million OP. Binance says an internal alert on large transfers fired at this point and its team started investigating.
Next. A Binance hot wallet sent 18,270 BTC to the attacker.
Then. The attacker used the signing service to abuse EIP-7702, an Ethereum feature that lets an account hand some execution rights to a smart contract. Binance says 50 signing transactions were used to manipulate the account’s nonce, its transaction counter, and install the malicious delegation.
23:56. The last unauthorised transfer, 2,961.9 ETH, finalised on-chain. Binance says it had been broadcast earlier and sat pending.
30 Oct, 00:10. Binance signed a new authorisation from its Binance14 hot wallet to the zero address. That cleared the delegation code.
Nearly four hours separate the first outflow from the last transfer.
Why did pausing withdrawals not end it?
How it happened
Binance describes “a sophisticated, multi-stage campaign”, not “a single isolated breach or a simple phishing incident”.
It lays out four stages.
June: the installer. Engineer A searched for a popular AI coding tool and downloaded a tampered Homebrew installer. Homebrew is a common package manager for Mac developers. Binance links to a SANS Internet Storm Center diary on the technique. Its security team caught it, replaced the device and rotated credentials. But Binance says Engineer A’s role, and his colleagues on the wallet team, were now known to the attacker.
September: the job offer. Engineer B was approached on a legitimate job platform by someone posing as a project director. A video interview with a supposed HR representative came first. The interviewer shared a social media account full of personal photos to build trust. In a second interview, held in a chat app, Engineer B was told to download an “assignment” onto his work computer.
The assignment was a code repository. Binance says it ran malicious code during setup, swapped a legitimate developer tool, pyenv, for a malicious copy and opened a channel to an outside server. It calls the malware a zero-day: endpoint security tools did not flag it.
20 Oct: the AI tool. From Engineer B’s machine, Binance says, the attacker “used an internal AI tool to gain control” over Engineers A and C. On Engineer A’s computer sat a container deployment permission token.
29 Oct: the signing service. That token, used from Engineer C’s computer, let the attacker deploy a container and reach the internal wallet signing service. From there, transactions could be started outside the normal withdrawal process.
That last point matters.
The private keys stayed private. The machine that uses them was told what to sign.
Binance also says its security team stopped 57 suspected North Korea-linked attempts this year, using fake interviews, poisoned developer tools, fake video-call apps and malicious browser extensions.
What the report does not say is what the internal AI tool is, what it was allowed to do, or why a deployment token on one laptop could reach a service that signs hot-wallet transactions.
Binance says some of that will stay private.
If the attack path is the lesson, how much of it will the industry be allowed to see?
The record, revised
Some of this changes what Binance said on the night.
The start time. Etherscan records cited by Decrypt put the EIP-7702 delegation at 20:21 UTC and the big ETH drain at 20:24 UTC, as we reported on 30 Oct. Binance now says the first outflows were XRP, at 20:05 UTC. The theft began about 16 minutes before the moment most trackers started their clocks.
The pause. At 08:47 UTC on 30 Oct, Binance said outflows stopped when withdrawals were paused. Its new report says suspending withdrawals “alone could not stop all unauthorized asset movements”, because the delegation lived on-chain and worked outside its withdrawal system. The last transfer landed at 23:56 UTC.
The key. The hot wallet used multi-party computation, or MPC, where signing power is split across several parties and no single private key exists. Binance says that is why it could not revoke the delegation at once. It had to build a special procedure.
A safety feature slowed the fix.
Ethereum developers have since floated a permanent opt-out from EIP-7702 delegation for wallets like this one.
The coverage figure. On 1 Nov Binance said about 95% of the impacted amount was covered, as Binance’s 95% figure on 1 Nov showed. The new report says 98% of impacted token assets had been replenished “as of 31 October”. The two may measure different things. Binance has not reconciled them.
Which number should users hold the exchange to?
Follow the funds
Binance’s report does not list addresses.
The public ledger for this theft is still the FBI’s: 628 addresses, including 608 on Ethereum, 19 on Bitcoin and one on Solana, that it asked exchanges and node operators to block, as the FBI’s TraderTraitor attribution set out.
Three figures need to stay apart.
| Measure | Figure | Source |
|---|---|---|
| Impacted (estimated) | ~$6.34 billion | Binance, 3 Nov |
| Stolen (on-chain estimate) | ~$6.43 billion | Elliptic, 2 Nov |
| Frozen or intercepted | ~$2.85 billion | Binance, 3 Nov; Elliptic, 2 Nov |
| Replenished by Binance | 98% of impacted token assets | Binance, as of 31 Oct |
Frozen is not recovered. Frozen tokens sit locked by issuers or partners until someone decides who gets them.
Replenished is not recovered either. That is Binance’s own money, put back in to cover users.
Elliptic said on Monday that the stolen funds had been spread across about 12,000 wallets on 11 blockchains, with about $3.24 billion still in linked addresses, mostly as ETH and BTC.
If $2.85 billion is frozen, who decides where it goes?
The response
Binance lists what it says is done as of 3 Nov.
- Moved the affected wallet system to a newly built environment.
- Rebuilt the internal AI tool and its access controls.
- Replaced affected devices and cancelled the engineers’ credentials and tokens.
- Ran security scans across all employee devices.
- Tightened risk controls on the wallet service and widened its automated monitoring of unusual behaviour.
Next, it promises an independent third-party review, more spending on AI-enabled detection and developer-environment security, and a security research fund with AI companies and security firms.
Withdrawals are coming back in batches, most recently the second withdrawal batch.
The report does not say who will run the review, when its findings will be published, or whether they will be published at all.
Will the second report be written by someone else?
Recap
Binance says one engineer’s poisoned installer in June gave the attacker a map of its wallet team.
A fake job interview in September put malware on a second engineer’s work computer.
An internal AI tool carried the attacker to a third machine and to a deployment token.
The keys were never stolen. The signing service was used.
The FBI says North Korea did it. The independent review has not started in public.
Protect yourself
- If you build software, treat any take-home “assignment” from a recruiter as hostile. Open it in a throwaway virtual machine, never on a work laptop.
- Install developer tools from the project’s own site or repository, not from a search ad or a look-alike page.
- Check what your EIP-7702 delegations point to in your wallet, and revoke any you did not set.
- Do not move funds in response to “Binance recovery” messages. Use only the exchange’s official site and app.
- Keep long-term holdings off any single exchange, however large.
The industry built wallets with no single key to steal. Who is checking the machines that tell them what to sign?
Corrections and new evidence: [email protected]
This article is for information only and is not investment advice.