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code-423n4 / 2022-05-sturdy-findings

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QA Report #160

Open code423n4 opened 2 years ago

code423n4 commented 2 years ago

C4-001 : The Contract Should approve(0) first

Impact - LOW

Some tokens (like USDT L199) do not work when changing the allowance from an existing non-zero allowance value. They must first be approved by zero and then the actual allowance must be approved.

IERC20(token).safeApprove(address(operator), 0);
IERC20(token).safeApprove(address(operator), amount);

Proof of Concept

  1. Navigate to the following contracts.
https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/ConvexCurveLPVault.sol#L141

https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/ConvexCurveLPVault.sol#L146
  1. When trying to re-approve an already approved token, all transactions revert and the protocol cannot be used.

Tools Used

None

Recommended Mitigation Steps

Approve with a zero amount first before setting the actual amount. Consider use safeIncreaseAllowance and safeDecreaseAllowance.

C4-002 : Check if amount > 0 before token transfer

Impact

Since _amount can be 0. Checking if (_amount != 0) before the transfer can potentially save an external call and the unnecessary gas cost of a 0 token transfer.

Proof of Concept

https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/LidoVault.sol#L57

All Contracts

Tools Used

None

Recommended Mitigation Steps

Consider checking amount != 0.

C4-003 : Front-runnable Initializers

Impact - LOW

All contract initializers were missing access controls, allowing any user to initialize the contract. By front-running the contract deployers to initialize the contract, the incorrect parameters may be supplied, leaving the contract needing to be redeployed.

Proof of Concept

  1. Navigate to the following contracts.
https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/YieldManager.sol#L60

https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/GeneralVault.sol#L61
  1. initialize functions does not have access control. They are vulnerable to front-running.

Tools Used

Manual Code Review

Recommended Mitigation Steps

While the code that can be run in contract constructors is limited, setting the owner in the contract's constructor to the msg.sender and adding the onlyOwner modifier to all initializers would be a sufficient level of access control.

C4-004 : # Missing zero-address check in the setter functions and initiliazers

Impact

Missing checks for zero-addresses may lead to infunctional protocol, if the variable addresses are updated incorrectly.

Proof of Concept

  1. Navigate to the following contracts.
https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/ConvexCurveLPVault.sol#L37

https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/YieldManager.sol#L60

https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/GeneralVault.sol#L61

https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/YieldManager.sol#L92

Tools Used

Code Review

Recommended Mitigation Steps

Consider adding zero-address checks in the discussed constructors: require(newAddr != address(0));.

C4-005 : Missing events for only functions that change critical parameters

Impact - Non critical

The afunctions that change critical parameters should emit events. Events allow capturing the changed parameters so that off-chain tools/interfaces can register such changes with timelocks that allow users to evaluate them and consider if they would like to engage/exit based on how they perceive the changes as affecting the trustworthiness of the protocol or profitability of the implemented financial services. The alternative of directly querying on-chain contract state for such changes is not considered practical for most users/usages.

Missing events and timelocks do not promote transparency and if such changes immediately affect users’ perception of fairness or trustworthiness, they could exit the protocol causing a reduction in liquidity which could negatively impact protocol TVL and reputation.

Proof of Concept

  1. Navigate to the following contract.
https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/YieldManager.sol#L64

See similar High-severity H03 finding OpenZeppelin’s Audit of Audius (https://blog.openzeppelin.com/audius-contracts-audit/#high) and Medium-severity M01 finding OpenZeppelin’s Audit of UMA Phase 4 (https://blog.openzeppelin.com/uma-audit-phase-4/)

Tools Used

None

Recommended Mitigation Steps

Add events to all functions that change critical parameters.

C4-006 : Critical changes should use two-step procedure

Impact - NON CRITICAL

The critical procedures should be two step process.

Proof of Concept

  1. Navigate to the following contract.
https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/ConvexCurveLPVault.sol#L37

Tools Used

Code Review

Recommended Mitigation Steps

Lack of two-step procedure for critical operations leaves them error-prone. Consider adding two step procedure on the critical functions.

C4-007 : # Pragma Version

Impact

In the contracts, floating pragmas should not be used. Contracts should be deployed with the same compiler version and flags that they have been tested with thoroughly. Locking the pragma helps to ensure that contracts do not accidentally get deployed using, for example, an outdated compiler version that might introduce bugs that affect the contract system negatively.

Proof of Concept

https://swcregistry.io/docs/SWC-103

All Contracts

Tools Used

Manual code review

Recommended Mitigation Steps

Upgrade pragma solidity 0.8.10.

C4-008: transferOwnership should be two step

Impact - NON CRITICAL

The owner is the authorized user in the solidity contracts. Usually, an owner can be updated with transferOwnership function. However, the process is only completed with single transaction. If the address is updated incorrectly, an owner functionality will be lost forever.

Proof of Concept

  1. Navigate to the following contracts.
https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/YieldManager.sol#L26

Tools Used

Code Review

Recommended Mitigation Steps

Lack of two-step procedure for critical operations leaves them error-prone. Consider adding two step procedure on the critical functions.

C4-009 : # Missing Re-entrancy Guard

Impact - LOW

The re-entrancy guard is missing on the some of the functions. The external interactions can cause to the re-entrancy vulnerability.

Proof of Concept

  1. Navigate to the following contract.
https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/LidoVault.sol#L30

https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/ConvexCurveLPVault.sol#L131

Tools Used

Code Review

Recommended Mitigation Steps

Follow the check effect interaction pattern or put re-entrancy guard.

C4-010 : Incompatibility With Rebasing/Deflationary/Inflationary tokens

Impact - LOW

PrePo protocol do not appear to support rebasing/deflationary/inflationary tokens whose balance changes during transfers or over time. The necessary checks include at least verifying the amount of tokens transferred to contracts before and after the actual transfer to infer any fees/interest.

Proof of Concept

  1. Navigate to the following contract.
https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/ConvexCurveLPVault.sol#L138

Tools Used

Manual Code Review

Recommended Mitigation Steps

C4-011 : Contract should have pause/unpause functionality

Impact

In case a hack is occuring or an exploit is discovered, the team (or validators in this case) should be able to pause functionality until the necessary changes are made to the system. Additionally, the gravity.sol contract should be manged by proxy so that upgrades can be made by the validators.

Because an attack would probably span a number of blocks, a method for pausing the contract would be able to interrupt any such attack if discovered.

To use a thorchain example again, the team behind thorchain noticed an attack was going to occur well before the system transferred funds to the hacker. However, they were not able to shut the system down fast enough. (According to the incidence report here: https://github.com/HalbornSecurity/PublicReports/blob/master/Incident%20Reports/Thorchain_Incident_Analysis_July_23_2021.pdf)

Proof of Concept

https://github.com/code-423n4/2022-05-sturdy/blob/main/smart-contracts/ConvexCurveLPVault.sol#L138

Tools Used

Code Review

Recommended Mitigation Steps

Pause functionality on the contract would have helped secure the funds quickly.

HickupHH3 commented 2 years ago

low: 001, 002, 011 nc: 003, 004, 005, 006 + 008, 007, 009 invalid: 010,