Hack Qubic: How the network saved 87% of stolen funds

On the night of October 17 to 18, an attacker emptied 1,404 Qubic wallets, or 2,940 billion QU. The response followed within hours: the Computors shut down the network, freezing 87.1% of the stolen funds in place, and MEXC blocked the account that had received the rest in about an hour. Twelve days later, the network is running again, 293 billion QU returned from the exchange on the chain and the first verified owners were reimbursed. The flaw did not come from the protocol but from the generation of seeds on certain Apple devices, and it also concerns intact wallets.

What happened on the night of October 17 to 18?

A seed reconstruction attack, executed with completely ordinary signed transfers. According to the status update published by Qubic, certain seeds had been generated with insufficient entropy when created on specific device and browser combinations. An attacker was able to reproduce them and then sign valid transfers from 1,404 identities in less than two hours. No transaction was falsified, and the core of the network was not affected: the flaw is located at the wallet level, where the seed phrase is born, not in the consensus.

The amount, QU 2,940 billion, represented approximately $1.4 million during October 18 ($0.000000477 per QU according to CoinGecko), making it a modest incident in value but large in number of victims. The reaction was rapid: the Computors, the 676 machines that validate the ticks, coordinated a network shutdown at tick 85,371,949. No more transactions were processed, and the 87.1% of funds still present on eight addresses controlled by the attacker found themselves frozen in place.

The remaining 12.9%, or QU379 billion, was sent in two transactions to a single deposit address at MEXC. The exchange froze the receiving account about an hour after the funds arrived, then suspended deposits and withdrawals from QUBIC on October 18 at Qubic’s request. Bitget did the same on the same day, citing “wallet maintenance.” Gate.io mentioned a “thorough technical verification” before any recovery.

Where are the funds today?

Under escrow for the most part, and back on the chain for the part passed by MEXC. During the pause, the affected funds were placed in a protected escrow, according to Qubic. On October 20, the quorum of Computors approved the recovery plan, the network resumed and Qubic announced on X that “the Qubic network is live again”, specifying that the first funds had been returned to verified owners, without giving the amount. A community survey had been organized beforehand, on an advisory basis: the decision was made by the quorum, in accordance with the network’s rules.

The rest is checked on the explorer. On October 28 at 8:07 UTC, at tick 87,353,465, 293 039 994 345 QU returned to the address that had sent them to MEXC ten days earlier (transaction). This address currently displays a zero balance, consistent with a move into sequestration. Funds returned from the exchange enter the same claims process, but the portal warns that this circuit is slower and depends on the cooperation of the authorities. If a balance is missing on arrival, Qubic says it wants to fill it with a community contribution, to reimburse each affected user.

On the market side, QUBIC lost around 19% between October 18 and 30, for a capitalization of around $57 million (CoinGecko). It is impossible to isolate the part of the incident in this decline, which occurred in a market itself with no appetite for risk.

How to recover your QU, and who is reimbursed first?

Through the official portal, and only it: weak-seed-reclaim.qubic.org. The tool does not move any funds, it collects requests; each payment is decided and applied by the quorum. An address verifier first allows you to know if an identity appears on the list of affected addresses, without signature or proof. The application itself is done in five steps.

1. Enter the identity affected and a new destination identitycreated with a secure seed on an up-to-date wallet, never a reuse of the old one.
2. Sign the message displayed in the wallet. At no time is the seed captured or sent.
3. Attach proof of ownership and a contact email address.
4. Keep the tracking link, no account being created.
5. Optionally, pass an identity check via Didit, which only transmits a result to Qubic, not the documents.

Why proof, if you can sign? Because the attacker holds exactly the same key as the owner: a signature doesn’t decide between anyone. The portal classifies the supporting documents by strength, from the receipt of withdrawal from an exchange to the affected address (the strongest) to the confirmation of an OTC deal, including a financing trail prior to the incident; a declaration on honor is only admitted in support. Simple and uncontested files go through a fast track, contested, weak or voluminous files are reread by the core developers.

The schedule is known. The first returns, launched the week of October 26, target cases without possible doubt: identities published with signature before the incident, OTC confirmable by the counterparty, funds from known community projects. Three milestones follow, in December 2026, February 2027 and April 2027the last covering all remaining valid requests.

Each approved request is publicly displayed (address and amount) for seven days before payment, and the amounts come from the frozen snapshot of the chain, not the requester’s input. Filing early accomplishes nothing; strong proof, yes. QEarn locks will return in later batches, and QX orders have been canceled. According to Qubic, more than 230 requests had been received at the end of October.

What should holders who have lost nothing do?

Check the origin of their seed, and migrate when in doubt. The patch in version 4.26.4 prevents the creation of new weak seeds, it does not repair old ones. Qubic is explicit: a web wallet created before this release should be treated as insecure,” even if your funds were never touched “. Same instructions for users of the iOS application and the web wallet on iOS, including excluding the list of affected addresses. The Android app wallets were not reported and no updates to the mobile apps were required.

The portal also mentions a “pending” list for funds from weak but not emptied seeds, released after verification. If your identity appears there, the procedure is the same: new identity on an up-to-date wallet, then request on the portal. And a rule that applies to all incidents of this type: the Qubic team never writes the first in a private message, never asks for a seed and does not charge any recovery fees. Support comes through a dedicated Discord channel, run by moderators; Qubic does not have a ticket system, which limits theft.

What the incident says about Qubic

Two readings coexist, and they are both well-founded. The first: a network capable of shutting down in a few hours at the decision of its validators saved 87% of the funds, where a chain without this lever would have watched the whole thing disappear. We had described the role of Computors and useful proof of work; this episode shows the operational side of it. The second: this same lever means that 676 machines can freeze balances and rewrite a situation, which the detractors of chain stops will not fail to point out.

On the cause, Qubic is withholding technical details until the end of the recovery, so as not to inspire copies, and promises a complete report. The security company SlowMist published on October 20 a analysis according to which the wallet seed generator would rely on the Math.random function, non-cryptographic, whose outputs would pass unencrypted in a network header; six consecutive values ​​would be enough, in his proof of concept, to reconstruct the state of the generator. Qubic has not confirmed this scenario, and its list of affected devices, focused on Safari and iOS, suggests a factor specific to these platforms.

This is also the second security incident of the year: on July 13, Qubic’s GitHub organization was compromised via an access token, with no loss of funds reported according to the post-mortem published the next day.

The next deadlines are set: technical report at the end of the recovery, first progress update on reimbursements in December, recovery to be announced at Bitget and Gate.io, still suspended on October 30 according to Qubic, and closure of claims on May 1, 2027. The question that remains open is simple to formulate: how many 1,404 owners will be able to produce proof that the attacker does not have?