How a zeroed oracle signature unlocked $9M from Hedera DeFi lender Bonzo Lend
Hedera-based lending protocol Bonzo Lend has locked withdrawals after an oracle verifier accepted a proof containing a zeroed signature and public key, permitting a pockets to borrow $9.05 million in opposition to 250 SAUCE.
Bonzo Lend and Bonzo Points remained paused as of July 13, whereas the protocol’s official standing web page listed Bonzo Lend and all affected asset markets as underneath upkeep.
Liquidity suppliers stay unable to withdraw whereas Bonzo Finance Labs and the Bonzo Finance Foundation decide a restoration path and the circumstances for reopening.
Wallet A primary deposited 250 SAUCE, value solely a few {dollars}. At 00:51 UTC, it submitted a SAUCE/wHBAR value replace that inflated the token’s worth by roughly 12 orders of magnitude regardless that the market value stayed close to 0.2 HBAR.
Eight seconds after the manipulated value reached the oracle’s on-chain storage, the pockets borrowed 6.63 million USDC.
It then borrowed 34.5 million wrapped HBAR, bringing the principal extracted by Wallet A to roughly $9.05 million at Bonzo’s reference costs.
How zeros handed the verifier
The submitted replace contained no legitimate oracle signature. Its signature subject was [0,0], whereas the referenced committee public key was additionally the zero level, recognized in cryptography as the purpose at infinity.
Supra’s verifier despatched these inputs to Hedera’s pairing precompile. Because each factors represented the mathematical identification, the pairing equation returned true as designed.
The verifier then handled that end result as proof of a committee signature as a result of it had not first rejected zero, identification, and off-subgroup inputs.
In plain English, the community answered the equation it obtained accurately, whereas the verifier mistook that reply for authorization.
Bonzo mentioned its lending contracts then adopted their programmed loan-to-value guidelines utilizing the value already saved by the oracle.
A separate Wallet B borrowed roughly $1 million whereas the irregular value remained stay. That pockets contacted Bonzo, recognized itself as a white-hat responder, and said that it supposed to return the funds.
Bonzo counted roughly $1 million as recovered, although the funds had but to be returned and the ultimate tally was nonetheless unsettled.
Bonzo reported that Supra mounted the verifier, however the lending pool stays closed.
The remaining questions embrace whether or not regression checks verify that the verifier rejects identification inputs, whether or not Bonzo provides price-deviation checks or tightens collateral parameters, and the way accessible belongings can be dealt with when withdrawals resume.
Bonzo’s official standing web page continued to checklist the incident as unresolved on July 13. Its newest formal replace, posted July 11, mentioned the protocol remained paused.
Bonzo has but to announce reimbursement, a reopening date, or user-facing withdrawal phrases, leaving liquidity suppliers depending on the restoration plan that comes subsequent.
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