[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"incident:the-dao-2016::en":3,"incidents-all::en":19},{"slug":4,"year":5,"date":6,"name":7,"category":8,"amount_label":9,"summary":10,"lesson":11,"published_at":12,"title":7,"meta_title":13,"meta_description":14,"keywords":15},"the-dao-2016",2016,"June 2016","The DAO","hack","~3.6M ETH moved out of the contract (publicly reported estimate)","The DAO was an investor-directed fund written entirely as Ethereum smart contracts: token holders would vote on which proposals received funding, with no manager in between. Its 2016 token sale gathered a large fraction of all circulating ether. In June 2016 an attacker exploited a reentrancy flaw in the code that let a participant withdraw their share: the contract sent ether out before it updated the sender's balance, so a malicious contract could call back into the withdrawal repeatedly and be paid again each time on a balance that had not yet been reduced. Roughly 3.6 million ETH was moved into a child contract subject to a holding period written into The DAO's own rules, which is what gave the community weeks to argue about a response. Ethereum's participants ultimately adopted a hard fork that moved the funds to a recovery contract. A minority rejected the fork on the grounds that the ledger should not be rewritten, and continued the original chain as Ethereum Classic.","Code that holds funds is only as good as its ordering. The flaw was not exotic cryptography but a sequence — pay first, update the record after — and that pattern is still what auditors look for first. The aftermath matters as much as the bug: a chain can only reverse a theft if enough of its participants agree to, and that agreement is a political fact about a community, not a technical guarantee you can rely on in advance.","2026-08-12T03:45:01+00:00","The DAO 2016: the reentrancy bug that split Ethereum","The DAO raised a large share of all circulating ether, then lost about 3.6 million of it to a reentrancy flaw. The response split the chain in two.",[7,16,17,18],"reentrancy","Ethereum hard fork","Ethereum Classic",[20,29,38,46,56,63,71,79,87,94,102,110,118,125,132,141,147,156,163,164,172],{"slug":21,"year":22,"date":23,"name":24,"category":8,"amount_label":25,"summary":26,"lesson":27,"published_at":28},"bybit-2025",2025,"February 2025","Bybit","~$1.46B in ETH and staked ETH (publicly reported estimate)","On 21 February 2025 attackers moved roughly $1.46 billion of ether and staked ether out of a Bybit cold wallet by manipulating what signers saw in a Safe multisig interface, so legitimate keyholders approved a transfer that was not what it appeared to be. The FBI attributed the attack to North Korea's Lazarus Group.","No key was stolen — the approval screen lied. Cold storage and multisig only help when every signer can verify, independently of that screen, what they are actually authorising.","2026-08-05T03:45:01+00:00",{"slug":30,"year":31,"date":32,"name":33,"category":8,"amount_label":34,"summary":35,"lesson":36,"published_at":37},"dmm-bitcoin-2024",2024,"May 2024","DMM Bitcoin","4,502.9 BTC (~$300m at the time, company-reported)","On 31 May 2024 DMM Bitcoin, a Japanese exchange registered with the Financial Services Agency, reported an unauthorised outflow of 4,502.9 BTC — worth roughly $300m at the time and one of the largest thefts in the country's history. The company said it would procure the equivalent bitcoin with support from the wider DMM group so that customer holdings were fully covered, and Japan's FSA issued a business improvement order. In December 2024 US and Japanese agencies publicly attributed the theft to North Korea-linked actors, and DMM announced it would cease its crypto business and transfer customer accounts to SBI VC Trade.","Registration and a solvent parent decided how this ended, not whether it happened. Japan's regime is among the strictest anywhere and the coins still left; what the rules and the group balance sheet bought was that customers were repaid rather than queued as creditors. Read a licence as a statement about who absorbs the loss, never as a claim that the loss is prevented — and note that the exchange itself did not survive being made whole.","2026-08-18T03:30:02+00:00",{"slug":39,"year":40,"date":41,"name":42,"category":8,"amount_label":43,"summary":44,"lesson":45,"published_at":28},"htx-2023",2023,"September 2023","HTX (formerly Huobi)","~5,000 ETH (~$8M) taken from a hot wallet (publicly reported estimate)","On 24 September 2023 roughly 5,000 ETH — about $8 million — was taken from a single HTX hot wallet. The exchange identified the attacker, negotiated the return of 95% of the funds and paid the remaining 5% as a white-hat bounty. Customer balances were covered in full.","Negotiating money back worked because the amount was small and the trail was public. That is an outcome, not a security control — no exchange can promise you the next attacker will take the deal.",{"slug":47,"year":48,"date":49,"name":50,"category":51,"amount_label":52,"summary":53,"lesson":54,"published_at":55},"celsius-2022",2022,"June 2022","Celsius Network","insolvency","Withdrawals frozen for roughly $4.7B in customer assets (publicly reported estimate)","The crypto lending platform froze all customer withdrawals during a market downturn and filed for bankruptcy weeks later. Its founder was subsequently charged with, and later pleaded guilty to, fraud for misrepresenting the platform's risk to depositors.","A platform paying yield on deposits is taking risk with your money somewhere. 'Where' and 'how much' are the questions a safety review has to ask before the good times end.","2026-07-19T01:00:17+00:00",{"slug":57,"year":48,"date":58,"name":59,"category":8,"amount_label":60,"summary":61,"lesson":62,"published_at":28},"crypto-com-2022","January 2022","Crypto.com","~$34M withdrawn from 483 accounts (publicly reported estimate)","On 20 January 2022 roughly $34 million in bitcoin, ether and other assets was withdrawn from 483 Crypto.com customer accounts. The withdrawals were approved without two-factor authentication being properly enforced. The company paused withdrawals, rebuilt the authentication flow, and reimbursed every affected user.","Two-factor authentication only protects you where the platform actually enforces it. The control existed here; the gap in enforcing it on the withdrawal path is what cost money.",{"slug":64,"year":48,"date":65,"name":66,"category":67,"amount_label":68,"summary":69,"lesson":70,"published_at":55},"ftx-2022","November 2022","FTX","fraud","Billions of dollars in customer funds misused (publicly reported estimate)","One of the largest exchanges globally collapsed within days after reporting revealed customer deposits had been comingled with, and lent to, a sister trading firm. Its founder was later convicted on multiple counts of fraud.","Scale, celebrity endorsements and slick branding say nothing about whether customer funds are actually segregated from the company's own trading book.",{"slug":72,"year":48,"date":73,"name":74,"category":8,"amount_label":75,"summary":76,"lesson":77,"published_at":78},"ronin-bridge-2022","March 2022","Ronin Bridge","~$600M in ETH and USDC (publicly reported estimate)","The Ronin bridge, which connected the Axie Infinity game's sidechain to Ethereum, was drained in March 2022 after attackers gained control of a majority of the small validator set whose signatures authorised withdrawals. Nothing was broken in the contract: the withdrawals were validly signed by the keys the system trusted. The loss was only discovered days later, when a user reported being unable to withdraw. US authorities subsequently attributed the theft to the North Korea-linked Lazarus Group.","A bridge is only as decentralised as its signer set. When a handful of keys can authorise every withdrawal, compromising those keys is the whole attack — and if nobody is watching the balance, it can take days for anyone to notice the money has gone.","2026-08-10T03:45:01+00:00",{"slug":80,"year":48,"date":81,"name":82,"category":51,"amount_label":83,"summary":84,"lesson":85,"published_at":86},"terra-luna-2022","May 2022","Terra \u002F LUNA","UST and LUNA lost effectively all of their value","TerraUSD was an algorithmic stablecoin that held its dollar peg not with reserves but with a mint-and-burn link to LUNA, the network's own volatile token: a UST below a dollar could always be exchanged for a dollar of newly created LUNA. In May 2022 the peg slipped and that mechanism worked in reverse — restoring it required minting ever more LUNA, which crushed LUNA's price and destroyed the very value the peg depended on. Both assets collapsed within days, and Terraform Labs and its founder later faced criminal and civil proceedings in the United States and South Korea.","A peg backed by a token the same system issues is circular. It holds while confidence holds and offers nothing to fall back on when confidence goes — which is the moment a stablecoin is supposed to be useful. High advertised yields on a stablecoin are a description of that risk, not a feature.","2026-08-11T03:45:01+00:00",{"slug":88,"year":48,"date":49,"name":89,"category":51,"amount_label":90,"summary":91,"lesson":92,"published_at":93},"three-arrows-capital-2022","Three Arrows Capital","Creditor claims of roughly $3.5B in the liquidation (publicly reported estimate)","Three Arrows Capital was a Singapore-based hedge fund that had become one of the largest borrowers in crypto, funding leveraged positions with loans from centralised lending desks. It held a substantial position in Terra's ecosystem, which lost effectively all of its value in May 2022, and it was exposed to other trades that moved against it as prices fell. When lenders issued margin calls in June 2022 the fund could not meet them. A court in the British Virgin Islands ordered its liquidation at the end of that month, and the liquidators sought recognition in the United States shortly after. The default did not stop at the fund: several of the lending platforms that had extended it credit disclosed losses, and some of them subsequently entered bankruptcy themselves. Singapore's regulator later issued prohibition orders against its founders.","Contagion in crypto is not mystical; it is a lending chain. A platform offering you a yield is lending your deposit to somebody, and the concentration of its loan book is the risk you are actually taking. That book is rarely published, so the question worth asking of any yield product is who the borrower is and what happens to your money if that borrower defaults.","2026-08-13T03:45:01+00:00",{"slug":95,"year":48,"date":96,"name":97,"category":8,"amount_label":98,"summary":99,"lesson":100,"published_at":101},"wormhole-2022","February 2022","Wormhole","~120,000 wrapped ETH (publicly reported estimate)","Wormhole, a bridge issuing wrapped assets across several chains, lost roughly 120,000 wrapped ether in February 2022 when an attacker exploited a flaw in how its Solana-side contract verified the guardian signatures that authorise a mint. The attacker was able to produce a mint that the contract accepted without a matching deposit on Ethereum, leaving the wrapped tokens undercollateralised. Jump Crypto, which backed the project, replaced the missing ether so that holders of the wrapped asset were made whole.","A wrapped token is a claim that something is held elsewhere. When the check that enforces that link is broken, the token keeps circulating and looking normal while the collateral behind it no longer exists — and whether users are made whole comes down to whether somebody with a balance sheet chooses to step in.","2026-08-14T03:45:02+00:00",{"slug":103,"year":104,"date":105,"name":106,"category":8,"amount_label":107,"summary":108,"lesson":109,"published_at":28},"kucoin-2020",2020,"September 2020","KuCoin","~$281M drained from hot wallets (publicly reported estimate)","On 25 September 2020 attackers drained roughly $281 million from KuCoin's hot wallets. About 84% was recovered over the following weeks through on-chain tracing, token issuers freezing and reissuing supply, and blacklisting by other exchanges. KuCoin's insurance fund covered the remainder, and users were made whole.","That recovery depended on other people's goodwill — issuers willing to freeze tokens and venues willing to blacklist addresses. Treat it as a favour the industry granted, not a protection you can count on.",{"slug":111,"year":112,"date":113,"name":114,"category":8,"amount_label":115,"summary":116,"lesson":117,"published_at":28},"binance-2019",2019,"May 2019","Binance","~7,000 BTC (~$40M at the time) taken from a hot wallet (publicly reported estimate)","On 7 May 2019 attackers withdrew roughly 7,000 BTC — about $40 million at the time — from a Binance hot wallet in a single transaction, using stolen API keys and phished credentials. Binance covered the entire loss from its Secure Asset Fund for Users, and customer balances were left untouched.","A reserve funded before a breach turns a hack into an accounting entry rather than a customer loss. Check that the fund exists and is disclosed today, not that one is promised afterwards.",{"slug":119,"year":112,"date":120,"name":121,"category":67,"amount_label":122,"summary":123,"lesson":124,"published_at":28},"bitfinex-crypto-capital-2019","2018–2019","Bitfinex \u002F Crypto Capital","~$850M in commingled customer and corporate funds (publicly reported estimate)","Across 2018 and 2019 Bitfinex had roughly $850 million of commingled customer and corporate money sitting with its payment processor, Crypto Capital Corp, whose accounts were seized by authorities in several countries. Affiliated stablecoin issuer Tether's reserves covered the gap; both firms settled with the New York Attorney General for $18.5 million in February 2021 without admitting wrongdoing.","The crypto never moved — the fiat leg did. Ask which outside company actually holds the cash side of an exchange's balance sheet, because that firm's legal problems become yours.",{"slug":126,"year":112,"date":127,"name":128,"category":67,"amount_label":129,"summary":130,"lesson":131,"published_at":55},"quadrigacx-2019","Early 2019","QuadrigaCX","~CA$190M in customer funds inaccessible (publicly reported estimate)","Canada's largest exchange at the time told customers it could no longer access roughly CA$190M in funds after its founder died while allegedly holding sole control of the cold-wallet keys. A later court-appointed investigation found many of the wallets had been empty long before his death, pointing to mismanagement and likely fraud rather than a pure accident.","Single-person key control is a structural failure waiting to happen — deliberate or not. A credible custodian never lets access depend on one individual.",{"slug":133,"year":134,"date":135,"name":136,"category":67,"amount_label":137,"summary":138,"lesson":139,"published_at":140},"bitconnect-2018",2018,"January 2018","BitConnect","~$2.4B taken from investors (figure cited by the US Department of Justice)","BitConnect invited users to exchange bitcoin for its own token and lock it in a lending programme that promised steady returns, said to be generated by a proprietary trading bot nobody outside the company could inspect. A multi-level referral structure paid existing participants to recruit new ones. After state securities regulators in the United States issued cease-and-desist orders, the lending platform was shut down in January 2018 and the token's value collapsed. US authorities later charged the operation as a fraud: a promoter pleaded guilty, and the founder was indicted and reported as a fugitive.","A fixed or guaranteed return in crypto is a claim about the future that nobody can make honestly. When the strategy behind it cannot be inspected and recruitment is rewarded, the returns are being paid by later deposits — which is a structure, not a market view, and it ends when deposits slow.","2026-08-08T03:45:01+00:00",{"slug":142,"year":134,"date":135,"name":143,"category":8,"amount_label":144,"summary":145,"lesson":146,"published_at":55},"coincheck-2018","Coincheck","~$530M in NEM (XEM) stolen (publicly reported estimate)","The Japanese exchange kept a large pool of a single token in an internet-connected hot wallet without a multi-signature setup. Attackers stole hundreds of millions of dollars' worth in one of the largest exchange hacks by value at the time.","Hot-wallet convenience has a price. The safest exchanges keep the large majority of customer funds offline, precisely so one breach can't drain everything.",{"slug":148,"year":149,"date":150,"name":151,"category":8,"amount_label":152,"summary":153,"lesson":154,"published_at":155},"parity-multisig-freeze-2017",2017,"November 2017","Parity Multisig Wallet Freeze","~513,000 ETH rendered permanently inaccessible (publicly reported estimate)","Parity's multi-signature wallets did not each carry their own logic. To save deployment cost, every wallet was a thin contract that delegated its behaviour to one shared library contract on the network. That library had been deployed without being initialised, so its ownership was still unclaimed. In November 2017 a user claimed it and then invoked its self-destruct function, which removed the library's code from the chain. Every wallet that depended on it was left pointing at nothing: the balances still exist in the ledger, but the code that could authorise a transfer no longer does. Public estimates put the amount stranded at roughly 513,000 ETH. Nobody took the funds, and no exploit moved them; they simply stopped being reachable. Proposals to recover them by protocol change were debated and not adopted. Months earlier, a separate flaw in the same wallet software had allowed an actual theft of around 150,000 ETH by public estimates.","Not every loss involves a thief. Shared code is a shared dependency, and a contract that delegates to a library inherits that library's failure modes without saying so on the tin. It also shows the limit of immutability from the user's side: the same property that stops anyone rewriting your balance stops anyone repairing it, and an unrecoverable mistake can be as expensive as an attack.","2026-08-09T03:45:01+00:00",{"slug":157,"year":5,"date":158,"name":159,"category":8,"amount_label":160,"summary":161,"lesson":162,"published_at":55},"bitfinex-2016","August 2016","Bitfinex","~120,000 BTC stolen (publicly reported estimate)","A security breach in Bitfinex's multi-signature wallet setup let attackers drain a large share of customer bitcoin in a single incident. The exchange spread the loss across all users' balances and later repaid affected customers over several years.","Even a widely used, multi-signature custody setup is only as strong as the systems and partners it depends on — 'multi-sig' alone isn't a safety guarantee.",{"slug":4,"year":5,"date":6,"name":7,"category":8,"amount_label":9,"summary":10,"lesson":11,"published_at":12},{"slug":165,"year":166,"date":167,"name":168,"category":8,"amount_label":169,"summary":170,"lesson":171,"published_at":28},"bitstamp-2015",2015,"January 2015","Bitstamp","~19,000 BTC taken from hot wallets (publicly reported estimate)","In January 2015 roughly 19,000 BTC was taken from Bitstamp's hot wallets following a targeted attack on exchange staff. Bitstamp suspended trading, rebuilt its infrastructure, and afterwards moved to third-party institutional custody with the large majority of customer assets held offline.","What changed Bitstamp's risk profile was the rebuilt custody model, not the apology. Judge an exchange by what it did after an incident, not by how quickly it published a statement.",{"slug":173,"year":174,"date":175,"name":176,"category":8,"amount_label":177,"summary":178,"lesson":179,"published_at":55},"mtgox-2014",2014,"February 2014","Mt. Gox","~850,000 BTC reported missing (publicly reported estimate)","Once the exchange handling the large majority of the world's Bitcoin trades, Mt. Gox abruptly halted withdrawals and filed for bankruptcy in Japan after disclosing that hundreds of thousands of customer and company bitcoins were gone — later attributed to theft that went undetected for years.","Trading volume and market dominance are not safety signals. An exchange can look like the industry's center of gravity and still be hollowed out inside."]