OAK — OnChain Attack Knowledge

Worked example · 2014-03

Poloniex withdrawal-race exploit — Bitcoin — 2014-03-04

Loss
12.3% of the bitcoin held by the exchange (absolute figures differ between outlets; one reports roughly $50K / 76.69 BTC).
OAK Techniques observed
OAK-T11.001 (Third-Party Signing-Vendor UI / Signing-Flow Compromise — broadly construed; the exchange as custodian to its users held signing authority over the hot wallet, and the compromise of that signing infrastructure is structurally T11.001). OAK-T15.003 (Operator-Endpoint Compromise — the attacker gained access to the exchange's hot-wallet server infrastructure, constituting an operator-endpoint state that enabled the signing-flow manipulation, though the exact entry vector was not publicly detailed at forensic granularity).
Attribution
confirmed The operator (posting as "Busoni") publicly disclosed the loss and accepted responsibility.
Key teaching point
The Poloniex March 2014 incident is an early exchange loss from a withdrawal-processing race condition. An exchange's accounting layer must serialise withdrawals; concurrent withdrawal requests drove a balance negative while payouts were still authorised. The operator disclosed quickly and socialised the loss across all user balances rather than failing outright.
Corrected 2026-10-11
the incident was a concurrent-withdrawal (negative-balance) flaw dated 2014-03-04, not a hot-wallet server compromise; the loss was spread across user balances rather than repaid wholly from personal funds.

Summary

Poloniex, a cryptocurrency exchange launched in 2014, lost 12.3% of the bitcoin it held on 2014-03-04. Per contemporaneous reporting, the attacker exploited a flaw that allowed many withdrawals to be entered at the same moment; the database showed a negative balance but the withdrawals were still authorised and paid out [fmag]``[ctele]. Poloniex attributed the cause to design errors in its accounting and security features that allowed simultaneous rather than sequential withdrawal processing [fmag].

The operator (posting as "Busoni"; one outlet names him as Tristan D'Agosta [spalmer]) accepted responsibility and said the debt would be repaid. To prevent a run, all customer balances were reduced by 12.3%; trading was halted and resumed after fixes, with a check added that halts withdrawals from accounts with negative balances [fmag]``[ctele]. Repayment was to come partly from the operator's own pocket and partly from raising trading fees from 0.2% to 1.5%, which users criticised [ctele].

Absolute loss figures are not consistent across outlets (97 BTC in one infographic, 76.69 BTC / roughly $50,000 in another) [spalmer]``[btcmag]. Earlier text in this file about a hot-wallet server compromise, a Circle acquisition price, full reimbursement and cold-storage architecture is unverified and has been removed.

Timeline (UTC)

When Event
2014-03-04 Concurrent withdrawals exploit negative-balance flaw; 12.3% of held BTC lost [fmag]
2014-03-04/05 Trading halted; all balances reduced 12.3%; withdrawals resume 2014-03-05 [ctele]
2014-03 Negative-balance check added to withdrawals [ctele]

Realised extraction

12.3% of exchange-held bitcoin; no recovery reported in the cited sources.

Public references

Techniques demonstrated (2)