Phase two of our 19 September disclosure: a public page that follows the stolen coins, updated as they move. Follow-up post: blink.sv/blog/phase-two-foll… Tracking page: bounty.blink.sv Bounty terms: blink.sv/bounty-terms On 3 October we published the post-mortem of the attack and a 50% bounty on the stolen funds. That was about what happened inside Blink. This is about where the money went. The page lists every address, transaction and Lightning channel we can tie to the attacker. Anyone can check each one on the public blockchain. Why public: We want everyone working on the bounty to have the same data we have, as up to date as ours, so they can be as effective as possible. The page is that data: we update it when the coins move and when we confirm something new. We are unlikely to catch him on our own. He is careful: his main Lightning node is reachable only over Tor, and his activity is spread across all hours of the day. What he cannot hide is the coins. Every time they move, they move in public. He already knows he is being watched, so publishing tells him nothing new. Formal channels matter and we use them, but they take weeks. A public page reaches exchanges, analysts and other teams the same day. He is still active: He prepared for weeks. He set up his Lightning node ten days before the attack, and nine days before it he already controlled about 14 BTC. He has not stopped: in the first week of October his main node opened a new channel, a second node of his showed itself, and he moved coins again. In the same week, on 5 October, he attacked @secondhq, a company that builds its own version of Ark (a new way to make Bitcoin payments), called Bark. He exploited a bug in Second's Ark server and took 0.75 BTC of their own funds; no user funds were affected (their disclosure: xitter.cf/secondhq/status/210806…). He paid for it from the same wallet that received the coins stolen from Blink, and at least partly with those very coins. We believe he may be preparing a cascading attack: using what he takes from each target to fund the next. If you build on Bitcoin as everyday money, there may be extra reason to be vigilant. If you run a Lightning node, a federation, a swap service or an exchange, check the page against what you see. What the page shows: The theft, how the coins moved after it, the coins he held before the attack, his Lightning nodes, his attack on Second's Ark server, and a Lightning wallet that is probably his. Every item is labelled proven, traced or probable. Transactions by exchanges or swap services are marked third-party: they are not accused of anything. About 0.87 BTC still sits untouched at five of the original addresses, 4.84 BTC at an address that is probably his, and 1.64 BTC at addresses he used in the attack on Second. The whole list downloads as a CSV. What stays off it: Anything partners told us in confidence. Personal data. Open security issues. Addresses whose owner we cannot establish. Other teams' incidents, until those teams agree or make them public. How you can help: Watch the addresses. If coins move, especially toward an exchange or any service that knows its customers, tell us straight away. Freezes depend on reaching the platform within hours. Report privately to [email protected] with BOUNTY in the subject. Please don't post leads publicly: it warns him, and it does not establish your priority. If you run a service and listed coins reach you, contact us before acting. If you control a listed address and are not involved, write to us and we will correct the page. The 50% bounty stands. 25% of what is recovered goes to whoever provides the information that leads to it, and another 25% to Bitcoin Beach, Bitcoin Ekasi, Afribit Kibera and the circular economies they choose. Everything on the page was already known to us, so re-tracing it does not qualify. Where the coins go next can. Live updates: Corrections appear as dated notes; we do not silently rewrite it. Spot an error? Write to [email protected] with CORRECTION in the subject. We timestamp the page's data on the Bitcoin blockchain with @opentimestamps at launch and with every update. One more thing: Blink never charges a fee to recover funds and never asks for keys, seed phrases or payments. Anyone offering "recovery services" in our name is not acting for Blink.

Full post-mortem of the September 19 attack, and a 50% bounty — up to 3.3 BTC — on the stolen funds: blink.sv/blog/sept-19-attack… Bounty terms: blink.sv/bounty-terms On Saturday September 19 an attacker used a flaw in our admin tools to take over 35 Blink accounts and withdraw about 6.61 BTC from 24 of them. A customer called one of our engineers at 11:39 UTC. Fifteen minutes later the whole custodial service was off. By that evening the hole was closed and the service was back. By Thursday September 24 every affected customer had their exact balance back, in bitcoin and in dollars, paid for by Blink's shareholders. No customer bears any loss. This was our fault. Not Bitcoin's, not our users'. To the 22 customers whose bitcoin was taken, and to the 3,817 people whose account details were looked up: we are sorry. How it happened: From October 2023 until that Saturday, anyone with a free Blink account and a web browser could give themselves the powers of our support staff: change the email or phone on any account, log in as that customer, raise their limits. Three unremarkable mistakes in how our admin tools checked permissions, stacked on top of each other, in code we inherited. The whole team was busy moving tens of thousands of users to self-custody under new regulation. Monitoring built to catch outages didn't catch an administrator doing things no administrator should. What it didn't touch: The money came out of our hot wallet. Most customer funds sit in multi-signature cold storage that nothing in our admin tools can reach. Non-custodial accounts were never in play: we don't hold those keys. What the attacker saw: They also read the details of 3,817 other accounts, in some cases a phone number or email address. Not names, not IDs, not addresses, not passwords, not seed phrases. We wrote to every holder we could reach, saying exactly what was seen. What stopped them: Two-factor authentication. The attacker logged in to nine accounts that had it on and tried eighteen times to move money. Zero loss. None of the 24 drained accounts had it on. If you take one thing from this post: Settings → Security and Privacy → Two-factor authentication. Then turn it on for your email too. What we changed: The flaw was fixed the same day and a third layer added two days later. The admin tools are off the public internet. The functions that change a customer's email or phone are switched off for everyone while we redesign them. All customer API keys were revoked. The hot wallet now holds a fraction of what it did. Security fixes are developed privately and published once deployed; the code stays open source. A standing security reporting channel is live, with rewards of up to 0.1 BTC for critical findings. Where the money is: Some still sits where it was withdrawn to. About 5 BTC has gone through a cross-chain swap service; a small amount reached an exchange that is cooperating. Criminal complaints are filed in El Salvador and Próspera, the regulators are notified, and we have traced the funds continuously. We are not expecting the money back. So we are putting a 50% bounty on it. Whoever provides the information that leads to a recovery gets 25% of what is recovered. Another 25% of anything recovered goes to Bitcoin Beach, Bitcoin Ekasi, Afribit Kibera and the circular economies they choose. No cap, no end date, paid only out of funds that actually come back. Write to [email protected]. We would far rather have spent this money on grassroots Bitcoin adoption than lost it to a thief. Shame on the attacker. One more thing: Ignore any email or SMS about this incident that contains a link: we contacted affected users only through messages in the Blink app. We will never ask for your PIN, password, seed phrase or a login code. The full post-mortem has the timeline, the technical detail for anyone running code derived from ours, and the bounty terms (links at the top).