Autonomint audit contest

A public audit contest on Sherlock (hedged stablecoin), completed on 4th December 2024. 0xSimao placed #1. 38 of his findings are published: 26 high severity and 12 medium.

What Autonomint is

Autonomint issues a hedged stablecoin: depositors post collateral and receive downside protection priced as an option, while a counterparty side (dCDS) takes the other half of that trade and earns the option fees, liquidations settling between them.

Scope

The Sherlock competition covered the borrowing and dCDS flows: deposit and withdrawal pricing as collateral recovers, strike-price redemption, fee application between depositor and counterparty, and the two liquidation types.

High severity findings

• Borrower withdrawing at a loss will cause losses for cds depositors that only withdraw after the price recovers
• Total cds deposited amount is incorrectly modified when cds depositor is at a loss, leading to stuck USDa
• Cds depositors profit up to the strike price is not redeemable as the total cds deposited amount is not increased
• Cds depositor profit is never taxed as the tax is only applied on the option fees
• Type 1 borrower liquidation will incorrectly add cds profit directly to totalCdsDepositedAmount
• Liquidation profit is never given to cds depositors who will take these losses
• borrowing::withdraw() at a loss will increase downside protected and misscalculate option fees
• Some liquidated collateral will be locked
• Cds amounts to reduce from each chain are incorrect and will lead to the inability to withdraw cds in one of the chains
• Potential Underflow in withdrawInterest
• borrowing::liquidate() sends the wrong liquidation index to the destination chain, overwritting liquidation information and getting collateral stuck
• Malicious user can call borrowing::calculateCumulativeRate() any number of times to inflate debt rate as lastEventTime is not updated
• Late abond holders steal USDa amount from liquidations from earlier abond holders
• CDSLib::withdrawUserWhoNotOptedForLiq() tax is not stored in the treasury
• Using LayerZero for synchronizing global states between two chains may lead to overwriting of global states.
• Borrower deposit, withdraw, deposit will reinit omniChainData.cdsPoolValue, getting profit stuck for cds depositors
• Missing Update to omnichain.totalAvailableLiquidationAmount in withdrawUser
• Liquidation will reduce total cds deposited amount, leading to incorrect option fees
• Borrowing::redeemYields debits ABOND from msg.sender but redeems to user using ABOND.State data from user
• The user overpays the USDA amount for downside protection while withdrawing
• totalCdsDepositedAmountWithOptionFees is incorrectly reduced in CDSLib::withdrawUser(), leading to stuck option fees
• Strike Price Not Validated Against Strike Percent, Leading to Exploitation Risk
• treasury.updateYieldsFromLiquidatedLrts() updates the yield in the current chain, but collateral may be in the other chain
• odosAssembledData can be manipulated
• cds owners can withdraw more than expected via manipulating excessProfitCumulativeValue
• Malicious users can DOS the protocol by setting downsideProtected to a large value

Medium severity findings

• Accumulated profit/losses by the cumulative value is not dealt with in borrowingLiquidation::liquidationType1(), leading to losses
• Interest generated by last bond will not go to anyone when liquidating as there is no bond amount to collect it
• GlobalVariables::oftOrCollateralReceiveFromOtherChains() calculates the fee as if it was the same in both chains, which is false
• GlobalVariables::oftOrCollateralReceiveFromOtherChains() always charges twice the collateral on COLLATERAL_TRANSFER, which is not needed
• Yield form LRTs are forever stuck in the protocol and cannot be withdrawn
• DOS on liquidation type 1 due to underflow in cds profits computation
• Protected downside is not updated when cds.getTotalCdsDepositedAmount() < downsideProtected
• Treasury.noOfBorrowers can be set to 0 by looping wei deposit<->withdrawals and DoS withdrawals and reset borrower debt
• CDSLib::calculateCumulativeRate() incorrectly only increment the local option fees when there are cds deposits
• Inconsistent Use of lastCumulativeRate in depositTokens() and withdraw() Functions in Borrowings Contract
• Withdrawing ionic during liquidation has a flaw
• An attacker can manipulate omniChainData.cdsPoolValue by breaking protocol.

The contest

View the contest page