InsureDAO contest - defsec's results

Handle

defsec

Vulnerability details

Impact

Contracts use assert() instead of require() in the Vault.

Per to Solidity’s documentation:

"Assert should only be used to test for internal errors, and to check invariants. Properly functioning code should never create a Panic, not even on invalid external input. If this happens, then there is a bug in your contract which you should fix. Language analysis tools can evaluate your contract to identify the conditions and function calls which will cause a Panic.”

Proof of Concept

1. Navigate to the following contract.

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/Vault.sol#L168

        if (available() < _amount) {
            //when USDC in this contract isn't enough
            uint256 _shortage = _amount - available();
            _unutilize(_shortage);

            assert(available() >= _amount);
        }

Tools Used

None

Recommended Mitigation Steps

Change to require().

Handle

defsec

Vulnerability details

Impact

the owner parameter are used for the onlyOwner modifier. In the state variable , proper check up should be done , other wise error in these state variable can lead to redeployment of contract. If the zero address is assigned to rebalanceManager parameter, that will fail all Owner functions.

Proof of Concept

1. Navigate to the following contract functions.

"https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/Registry.sol#L31"

2. Adding zero address into the owner leads to failure of onlyOwner only functions.

Tools Used

Code Review

Recommended Mitigation Steps

Add proper zero address validation.

Handle

defsec

Vulnerability details

Impact

On the ERC20, There is a known problem named as Approve/TransferFrom race condition. On the transferFrom, allowance max check has not been added.

Proof of Concept

1. Navigate to the following contract.

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/InsureDAOERC20.sol#L152

    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) public virtual override returns (bool) {
        uint256 currentAllowance = _allowances[sender][_msgSender()];
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
            unchecked {
                _approve(sender, _msgSender(), currentAllowance - amount);
            }
        }

        _transfer(sender, recipient, amount);

        return true;
    }

2. Max Allowance check has not been added into the function. ERC20 standart (Openzeppelin) is not followed.

Tools Used

None

Recommended Mitigation Steps

Consider to use openzeppelin erc20 contract. The sample transferFrom function can be seen from below.

    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) public virtual override returns (bool) {
        uint256 currentAllowance = _allowances[sender][_msgSender()];
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
            unchecked {
                _approve(sender, _msgSender(), currentAllowance - amount);
            }
        }

        _transfer(sender, recipient, amount);

        return true;
    }

https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol#L161

Handle

defsec

Vulnerability details

The setFeeRate function does not have any upper or lower bounds. Values that are too large will lead to reversions in several critical functions.

Proof of Concept

• The setFeeRate function sets the transaction fee rates for the market in which the function is called. In this context, the transaction fee is the percentage of a transaction that is taken by the protocol and moved to a designated reserve account. As the name suggests, transaction fees factor in to many of the essential transaction types performed within the system.
• Navigate to "https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/Parameters.sol#L177".
• On the function there is no upper and lower bound defined. Therefore, users can pay higher fees.

Tools Used

None

Recommended Mitigation Steps

Consider to define upper and lower bounds on the fee array.

Handle

defsec

Vulnerability details

Impact

Hardhat console is an unnecessary import in all contracts since it is used solely for development. It can therefore be removed.

Proof of Concept

1. Navigate to the following contracts.

"https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/Factory.sol#L14"

"https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/Parameters.sol#L13"

"https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/IndexTemplate.sol#L7"

Tools Used

None

Recommended Mitigation Steps

Consider to delete 'import "hardhat/console.sol"' for the gas optimization.

Handle

defsec

Vulnerability details

Impact

On the deposit and other functions, some of the functions are checked when the contract is paused. However, other functions like unlock or transferinsturance does not have any pause protection.

Proof of Concept

1. Navigate to the following contract.

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/PoolTemplate.sol#L260

Tools Used

None

Recommended Mitigation Steps

Review all the function behaviours and put extra pause check.

Handle

defsec

Vulnerability details

Impact

In some cases, having function arguments in calldata instead of memory is more optimal.

Consider the following generic example:

contract C {
function add(uint[] memory arr) external returns (uint sum) {
uint length = arr.length;
for (uint i = 0; i < arr.length; i++) {
sum += arr[i];
}
}
}

In the above example, the dynamic array arr has the storage location memory. When the function gets called externally, the array values are kept in calldata and copied to memory during ABI decoding (using the opcode calldataload and mstore). And during the for loop, arr[i] accesses the value in memory using a mload. However, for the above example this is inefficient. Consider the following snippet instead:

contract C {
function add(uint[] calldata arr) external returns (uint sum) {
uint length = arr.length;
for (uint i = 0; i < arr.length; i++) {
sum += arr[i];
}
}
}

In the above snippet, instead of going via memory, the value is directly read from calldata using calldataload. That is, there are no intermediate memory operations that carries this value.

Gas savings: In the former example, the ABI decoding begins with copying value from calldata to memory in a for loop. Each iteration would cost at least 60 gas. In the latter example, this can be completely avoided. This will also reduce the number of instructions and therefore reduces the deploy time cost of the contract.

In short, use calldata instead of memory if the function argument is only read.

Note that in older Solidity versions, changing some function arguments from memory to calldata may cause "unimplemented feature error". This can be avoided by using a newer (0.8.*) Solidity compiler.

Examples Note: The following pattern is prevalent in the codebase:

function f(bytes memory data) external {
(...) = abi.decode(data, (..., types, ...));
}

Here, changing to bytes calldata will decrease the gas. The total savings for this change across all such uses would be quite significant.

Proof Of Concept

Examples:

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/Factory.sol#L176

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/Factory.sol#L186

Tools Used

None

Recommended Mitigation Steps

Change memory definition with calldata.

Handle

defsec

Vulnerability details

Impact

The contract has an unnecessary ==true comparison in its require statement. Since require already checks if the condition is true, there is no need for it to be compared.

Proof of Concept

1. Navigate the following contract lines.

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/PoolTemplate.sol#L612

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/Factory.sol#L122

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/Factory.sol#L142

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/Factory.sol#L166

Tools Used

Code Review

Recommended Mitigation Steps

Removing == true saves a tiny amount of gas.

Handle

defsec

Vulnerability details

Impact

The use of _msgSender() when there is no implementation of a meta transaction mechanism that uses it, such as EIP-2771, very slightly increases gas consumption.

Proof of Concept

_msgSender() is utilized three times where msg.sender could have been used in the following function.

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/InsureDAOERC20.sol#L105

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/InsureDAOERC20.sol#L135

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/InsureDAOERC20.sol#L159

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/InsureDAOERC20.sol#L165

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/InsureDAOERC20.sol#L188

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/InsureDAOERC20.sol#L220

Tools Used

None

Recommended Mitigation Steps

Replace _msgSender() with msg.sender if there is no mechanism to support meta-transactions like EIP-2771 implemented.

Handle

defsec

Vulnerability details

Impact

!= 0 is a cheaper operation compared to > 0, when dealing with uint.

Proof of Concept

1. Navigate to the following contracts.

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/IndexTemplate.sol#L172

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/IndexTemplate.sol#L166

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/IndexTemplate.sol#L172

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/IndexTemplate.sol#L246

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/IndexTemplate.sol#L231

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/PoolTemplate.sol#L218

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/PoolTemplate.sol#L263

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/PoolTemplate.sol#L321

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/PoolTemplate.sol#L391

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/PoolTemplate.sol#L437

Tools Used

Code Review

Recommended Mitigation Steps

Use "!=0" instead of ">0" for the gas optimization.

Handle

defsec

Vulnerability details

Impact

These checks are pretty much useless as uint can never be negative. Remove them to save some gas.

Example :

for( uint i; i<5;i++)

Proof of Concept

1. Navigate to the following contract.

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/Vault.sol#L109

Tools Used

None

Recommended Mitigation Steps

Consider to replace uint=0 to uint.

Handle

defsec

Vulnerability details

Impact

(After) Solidity 0.8.0 Version has built-in overflow protection mechanism. However, the following contract is still using sub function.

Proof of Concept

1. Navigate to the following function.

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/PoolTemplate.sol#L938

Tools Used

None

Recommended Mitigation Steps

Delete redundant code.

Handle

defsec

Vulnerability details

Impact

Using newer compiler versions and the optimizer gives gas optimizations and additional safety checks are available for free.

The advantages of versions 0.8.* over <0.8.0 are:

• Safemath by default from 0.8.0 (can be more gas efficient than library based safemath.)
• Low level inliner : from 0.8.2, leads to cheaper runtime gas. Especially relevant when the contract has small functions. For example, OpenZeppelin libraries typically have a lot of small helper functions and if they are not inlined, they cost an additional 20 to 40 gas because of 2 extra jump instructions and additional stack operations needed for function calls.
• Optimizer improvements in packed structs: Before 0.8.3, storing packed structs, in some cases used an additional storage read operation. After EIP-2929, if the slot was already cold, this means unnecessary stack operations and extra deploy time costs. However, if the slot was already warm, this means additional cost of 100 gas alongside the same unnecessary stack operations and extra deploy time costs.
• Custom errors from 0.8.4, leads to cheaper deploy time cost and run time cost. Note: the run time cost is only relevant when the revert condition is met. In short, replace revert strings by custom errors.

Proof of Concept

1. The contest repository contracts contain different pragma versions. The contracts pragma version can be updated to 0.8.4 for the gas optimization.

• Affected Contracts

"InsureDAOERC20 Contract" - Floating Pragma version 0.8.0 is used in the all contracts. (https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/InsureDAOERC20.sol#L3)

Tools Used

None

Recommended Mitigation Steps

Consider to upgrade pragma to at least 0.8.4.

Handle

defsec

Vulnerability details

Impact

Reading array length at each iteration of the loop takes 6 gas (3 for mload and 3 to place memory_offset) in the stack.

Caching the array length in the stack saves around 3 gas per iteration.

Proof of Concept

1. Navigate to the following smart contract line.

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/Factory.sol#L176

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/Factory.sol#L186

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/IndexTemplate.sol#L655

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/PoolTemplate.sol#L343

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/PoolTemplate.sol#L671

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/PoolTemplate.sol#L703

Tools Used

None

Recommended Mitigation Steps

Consider to cache array length.

Handle

defsec

Vulnerability details

Impact

For the arithmetic operations that will never over/underflow, using the unchecked directive (Solidity v0.8 has default overflow/underflow checks) can save some gas from the unnecessary internal over/underflow checks.

Proof of Concept

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/InsureDAOERC20.sol#L159

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/InsureDAOERC20.sol#L220

Tools Used

None

Recommended Mitigation Steps

Consider applying unchecked arithmetic where overflow/underflow is not possible.

Handle

defsec

Vulnerability details

Impact

'immutable' greatly reduces gas costs. There are variables that do not change so they can be marked as immutable to greatly improve the gast costs.

Proof of Concept

1. For instance : https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/Vault.sol#L27

Tools Used

Code Review

Recommended Mitigation Steps

Mark variables as immutable.

Handle

defsec

Vulnerability details

Impact

There is a function declared as public that are never called internally within the contract. It is best practice to mark such functions as external instead, as this saves gas (especially in the case where the function takes arguments, as external functions can read arguments directly from calldata instead of having to allocate memory).

Proof of Concept

 +  InsureDAOERC20 (Context, IERC20, IERC20Metadata)
    - [Pub] name
    - [Pub] symbol
    - [Pub] decimals
    - [Pub] totalSupply
    - [Pub] balanceOf
    - [Pub] transfer #
    - [Pub] allowance
    - [Pub] approve #
    - [Pub] transferFrom #
    - [Pub] increaseAllowance #
    - [Pub] decreaseAllowance #


 +  Parameters (IParameters)
    - [Pub] getOwner

 +  PoolTemplate (InsureDAOERC20, IPoolTemplate, IUniversalMarket)
    - [Pub] deposit #
    - [Pub] unlock #
    - [Pub] getPremium
    - [Pub] valueOfUnderlying
    - [Ext] pendingPremium
    - [Pub] worth
    - [Pub] allocatedCredit
    - [Pub] availableBalance
    - [Pub] utilizationRate
    - [Pub] totalLiquidity
    - [Pub] originalLiquidity


 +  Vault (IVault)
    - [Pub] underlyingValue
    - [Pub] valueAll
    - [Pub] available
    - [Pub] getPricePerFullShare
    - [Pub] setController #
       - modifiers: onlyOwner

Tools Used

Code Review

Recommended Mitigation Steps

All of the public functions in the contract are not called internally, so access can be changed to external to reduce gas.

Handle

defsec

Vulnerability details

Impact

++i is more gas efficient than i++ in loops forwarding.

Proof of Concept

1. Navigate to the following contracts.

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/Vault.sol#L109

Tools Used

Code Review

Recommended Mitigation Steps

It is recommend to use unchecked{++i} and change i declaration to uint256.

Handle

defsec

Vulnerability details

Impact

On the InsureDAOERC20, transferFrom function is vulnerable on the re-entrancy.

Proof of Concept

1. Navigate to the following contract. Approve function is written after transfer call. It is not possible to exploit on the current environment but that can be possible on the EVM.

    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);

        uint256 currentAllowance = _allowances[sender][_msgSender()];
        require(
            currentAllowance >= amount,
            "ERC20: transfer amount exceeds allowance"
        );

        _approve(sender, _msgSender(), currentAllowance - amount);

        return true;
    }

Tools Used

Code Review

Recommended Mitigation Steps

Follow check effect interaction pattern. Consider to use openzeppelin erc20 contract. The sample transferFrom function can be seen from below.

  function transferFrom(
      address sender,
      address recipient,
      uint256 amount
  ) public virtual override returns (bool) {
      uint256 currentAllowance = _allowances[sender][_msgSender()];
      if (currentAllowance != type(uint256).max) {
          require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
          unchecked {
              _approve(sender, _msgSender(), currentAllowance - amount);
          }
      }

      _transfer(sender, recipient, amount);

      return true;
  }

https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol#L161

Handle

defsec

Vulnerability details

Impact

Shortening revert strings to fit in 32 bytes will decrease deploy time gas and will decrease runtime gas when the revert condition has been met.

Revert strings that are longer than 32 bytes require at least one additional mstore, along with additional overhead for computing memory offset, etc.

Proof of Concept

Revert strings > 32 bytes are here:

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/InsureDAOERC20.sol#L302

https://github.com/code-423n4/2022-01-insure/blob/19d1a7819fe7ce795e6d4814e7ddf8b8e1323df3/contracts/InsureDAOERC20.sol#L330

Tools Used

Manual Review

Recommended Mitigation Steps

Shorten the revert strings to fit in 32 bytes. That will affect gas optimization.