fix dust surplus claim in recovery mode liquidation

rayeaster commented 4 months ago

add POC from immunefi contest for flashloan fee escape due to division loss
add fix to avoid dust surplus in recovery mode liquidation https://gist.github.com/dapp-whisperer/c023eacc977e0f07c0c81a288b5cf090

Summary by CodeRabbit

New Features
- Enhanced liquidation process to handle surplus collateral more effectively based on internal collateral ratios.
- Introduced new test scenarios to validate the improved liquidation logic and ensure security against flash loan attacks.
- Improved surplus management and added surplus cap checks for collateral and user pools during liquidation.
- Refactored code to include additional conditional assignments and logging for better stake management.

coderabbitai[bot] commented 4 months ago

Walkthrough

This update introduces enhancements to the liquidation process in a smart contract system, focusing on better handling of collateral surplus during liquidation based on the Insurance Coverage Ratio (ICR) against the Minimum Collateral Ratio (MCR). It also adds a test for liquidation scenarios where the ICR is below the MCR, ensuring no surplus is generated in such cases. Additionally, it addresses potential vulnerabilities by introducing a mechanism to prevent flash loan fee escape attacks.

Changes

File Path	Change Summary
`.../contracts/LiquidationLibrary.sol`	Added conditional check for `_collSurplus` handling based on `_checkICRAgainstMCR`, updating `_cappedColPortion` accordingly.
`.../foundry_test/CdpManager.Liquidation.t.sol`	New test `testSurplusInRMWhenICRBelowMCR` added to simulate liquidation with ICR < MCR.
`.../foundry_test/FlashLoanAttack.t.sol`	Introduced `IActivePool` interface and `FlashFeeEscapeBorrower` contract; added `testFeeEscapeAttack()` function.

Related issues

ebtc-protocol/ebtc#115: The improvements to the liquidation process and the addition of recovery mode conditions in the contract changes could align with the objectives of enhancing system health and managing recovery mode more effectively.

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getrecon-bot commented 4 months ago


Job ID	4e85689a-33ca-4cb4-9684-91bb157793b7
Command	`yarn && git submodule init && git submodule update && solc-select use 0.8.17 && cd packages/contracts/ && yarn echidna --test-mode assertion --test-limit 300000`
Instance ID	`i-0ce902b6861cf0099`
Instance Type	`c5.2xlarge`
Status	Started
Elapsed

getrecon-bot commented 4 months ago


Job ID	4e85689a-33ca-4cb4-9684-91bb157793b7
Command	`yarn && git submodule init && git submodule update && solc-select use 0.8.17 && cd packages/contracts/ && yarn echidna --test-mode assertion --test-limit 300000`
Instance ID	`i-0ce902b6861cf0099`
Instance Type	`c5.2xlarge`
Status	Running
Elapsed	43 seconds

getrecon-bot commented 4 months ago


Job ID	4e85689a-33ca-4cb4-9684-91bb157793b7
Command	`yarn && git submodule init && git submodule update && solc-select use 0.8.17 && cd packages/contracts/ && yarn echidna --test-mode assertion --test-limit 300000`
Instance ID	`i-0ce902b6861cf0099`
Instance Type	`c5.2xlarge`
Status	Running
Elapsed	44 seconds

getrecon-bot commented 4 months ago


Job ID	4e85689a-33ca-4cb4-9684-91bb157793b7
Command	`yarn && git submodule init && git submodule update && solc-select use 0.8.17 && cd packages/contracts/ && yarn echidna --test-mode assertion --test-limit 300000`
Instance ID	`i-0ce902b6861cf0099`
Instance Type	`c5.2xlarge`
Status	Success
Elapsed	17 hours 35 minutes 4 seconds

ebtc-protocol / ebtc