Incident Overview
Saddle Finance, an automated market maker (AMM) on Ethereum, suffered an attack on April 30, 2022, which exploited smart contracts and resulted in roughly $11m of crypto being stolen
Saddle Finance, an automated market maker (AMM) on Ethereum, experienced a series of transactions on April 30, 2022, which resulted in the loss of roughly $11 million worth of cryptocurrency. The attack was carried out in three transactions, with one of them being a whitehat who managed to rescue approximately 25% of the total amount taken. The exploit was made possible due to a previously known bug that had not been properly patched.
Saddle Finance is an AMM that focuses on stable swaps of assets that are pegged or similar in nature. It uses concepts from Curve, which has two distinct swap pools: Standard and Meta. The Meta pool allows liquidity in one pool to be used in additional pools.
The root cause of the attack on Saddle Finance was the inconsistent price calculations of assets within its Meta pool. The mispricing was caused by the omission of math that calculates the value of tokens given, based upon the base virtual price of the LP token. The bug was present within the library called MetaSwapUtils, which is used for calculating swaps, deposits, and withdrawals.
Despite the protocol's quick reaction to the exploit and the migration to a supposedly fixed MetaSwapUtils library, the incorrect swap calculation present in the original code was still present in live pools.
Exploit TXs:
https://etherscan.io/tx/0x2b023d65…f7da56
https://etherscan.io/tx/0xe7e04747…73d7b8
Exploiter:
https://etherscan.io/address/0x63341ba9…a55ac0
Incident Report
Protocol Information
Market Context at Time of Hack
What the Attacker Needed to Succeed
Understanding the prerequisites for this type of attack helps auditors identify protocols that are most at risk and helps developers build better defenses.
What Auditors Should Check
If you're auditing a protocol with similar architecture to Saddle Finance, these are the critical security checks that could have prevented this incident (April 2022).
- Verify all logic paths related to Flashloan Swap Logic Exploit / Other are guarded by proper access controls and input validation - see the Flash Loans Attacks attack class for patterns
- Review privileged functions (owner, admin, governance) for potential abuse vectors - centralization risks should be documented and bounded with timelocks or multi-sigs
Master these auditing techniques with hands-on labs and real exploit scenarios in the Smart Contract Hacking course.
Free TrialFunds Recovery
Recovered
$2.5M
Net Loss
8503000
Related Attack Classes
The technique used in this hack maps to these vulnerability classes in our security curriculum:
Proof-of-Concept Exploits
On-Chain Evidence & References
Sources & References
Learn to Prevent the Next Saddle Finance
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