Inverse Finance contest - 0xNazgul's results

Lines of code

https://github.com/code-423n4/2022-10-inverse/blob/main/src/Oracle.sol#L82 https://github.com/code-423n4/2022-10-inverse/blob/main/src/Oracle.sol#L116

Vulnerability details

Impact

According to Chainlink's documentation, the latestAnswer function is deprecated. This function does not error if no answer has been reached but returns 0, causing an incorrect price fed from Oracle.sol.

Proof of Concept

Chainlink - API Reference

Tools Used

Manual Review

Recommended Mitigation Steps

Use the latestRoundData function to get the price instead. Add checks on the return data with proper revert messages if the price is stale or the round is uncompleted.

[NAZ-L1] Signature Malleability of EVM's ecrecover()

Severity: Low Context: Market.sol#L425, Market.sol#L489, DBR.sol#L226

Description: The function calls the Solidity ecrecover() function directly to verify the given signatures. However, the ecrecover() EVM opcode allows malleable (non-unique) signatures and thus is susceptible to replay attacks.

Although a replay attack seems not possible here since the nonce is increased each time, ensuring the signatures are not malleable is considered a best practice.

Recommendation: Use the ecrecover function from OpenZeppelin's ECDSA library for signature verification. (Ensure using a version > 4.7.3 for there was a critical bug >= 4.1.0 < 4.7.3).

[NAZ-L2] Lack of Event Emission For Critical Functions

Severity: Low Context: Market.sol#L118, Market.sol#L124, Market.sol#L130, Market.sol#L136, Market.sol#L142, Market.sol#L149, Market.sol#L161, Market.sol#L172, Market.sol#L183, Market.sol#L194, DBR.sol#L53, DBR.sol#L62, BorrowController.sol#L26, BorrowController.sol#L32, BorrowController.sol#L38, Oracle.sol#L44, Oracle.sol#L53, Oracle.sol#L61, Fed.sol#L48, Fed.sol#L57, Fed.sol#L66, Fed.sol#L75, SimpleERC20Escrow.sol#L36, INVEscrow.sol#L59, GovTokenEscrow.sol#L43

Description: Several functions update critical parameters that are missing event emission. These should be performed to ensure tracking of changes of such critical parameters.

Recommendation: Consider adding events to functions that change critical parameters.

[NAZ-L3] Missing Equivalence Checks in Setters

Severity: Low Context: Market.sol#L118, Market.sol#L124, Market.sol#L130, Market.sol#L136, Market.sol#L142, Market.sol#L149, Market.sol#L161, Market.sol#L172, Market.sol#L183, Market.sol#L194, DBR.sol#L53, DBR.sol#L62, DBR.sol#L81, DBR.sol#L90, DBR.sol#L99, BorrowController.sol#L26, BorrowController.sol#L32, BorrowController.sol#L38, Oracle.sol#L44, Oracle.sol#L53, Oracle.sol#L61, Fed.sol#L48, Fed.sol#L57, Fed.sol#L66

Description: Setter functions are missing checks to validate if the new value being set is the same as the current value already set in the contract. Such checks will showcase mismatches between on-chain and off-chain states.

Recommendation: This may hinder detecting discrepancies between on-chain and off-chain states leading to flawed assumptions of on-chain state and protocol behavior.

[NAZ-L4] Missing Zero-address Validation

Severity: Low Context: Market.sol#L118, Market.sol#L124, Market.sol#L130, Market.sol#L136, Market.sol#L142, DBR.sol#L53, DBR.sol#L81, DBR.sol#L90, DBR.sol#L99, BorrowController.sol#L26, BorrowController.sol#L32, BorrowController.sol#L38, Oracle.sol#L44, Oracle.sol#L53, Oracle.sol#L61, Fed.sol#L48, Fed.sol#L66, Fed.sol#L75, SimpleERC20Escrow.sol#L36, INVEscrow.sol#L59, GovTokenEscrow.sol#L43

Description: Lack of zero-address validation on address parameters may lead to transaction reverts, waste gas, require resubmission of transactions and may even force contract redeployments in certain cases within the protocol.

Recommendation: Consider adding explicit zero-address validation on input parameters of address type.

[NAZ-L5] Missing Events In Initialize Functions

Severity: Low Context: SimpleERC20Escrow.sol#L25, INVEscrow.sol#L44, GovTokenEscrow.sol#L30

Description: None of the initialize functions emit emit init-specific events. They all however have the initializer modifier (from Initializable) so that they can be called only once. Off-chain monitoring of calls to these critical functions is not possible.

Recommendation: It is recommended to emit events in your initialization functions.

[NAZ-N1] Missing Visibility of State Variables

Severity: Informational Context: Market.sol#L52

Description: Some state varaibles are missing visibility.

Recommendation: Consider adding visibility to all state variables

[NAZ-N2] Line Length

Severity: Informational Context: Market.sol#L124, Market.sol#L133, Market.sol#L145, Market.sol#L168, Market.sol#L173, Market.sol#L179, Market.sol#L184, Market.sol#L195, Market.sol#L209, Market.sol#L350, Market.sol#L360, Market.sol#L377, Market.sol#L433, Market.sol#L497, Market.sol#L526, Market.sol#L555, Market.sol#L587, Market.sol#L618, DBR.sol#L50, DBR.sol#L58, DBR.sol#L116, DBR.sol#L129, DBR.sol#L181, DBR.sol#L320-L321, Oracle.sol#L12-L14, Oracle.sol#L53, Fed.sol#L99, SimpleERC20Escrow.sol#L49, INVEscrow.sol#L25, INVEscrow.sol#L62, GovTokenEscrow.sol#L16, GovTokenEscrow.sol#L56

Description: Max line length must be no more than 120 but many lines are extended past this length.

Recommendation: Consider cutting down the line length below 120.

[NAZ-N3] Function && Variable Naming Convention

Severity Informational Context: Market.sol#L55-L56, Market.sol#L97, Market.sol#L101, Market.sol#L226, Market.sol#L245, Market.sol#L323, Market.sol#L344, Market.sol#L353, Market.sol#L389, Market.sol#L460, DBR.sol#L13-L14, DBR.sol#L21-L22, DBR.sol#L262, DBR.sol#L266

Description: The linked variables do not conform to the standard naming convention of Solidity whereby functions and variable names(local and state) utilize the mixedCase format unless variables are declared as constant in which case they utilize the UPPER_CASE_WITH_UNDERSCORES format. Private variables and functions should lead with an _underscore.

Recommendation: Consider naming conventions utilized by the linked statements are adjusted to reflect the correct type of declaration according to the Solidity style guide.

[NAZ-N4] Code Structure Deviates From Best-Practice

Severity: Informational Context: Market.sol#L92, DBR.sol#L44, BorrowController.sol#L17, Oracle.sol#L35, Fed.sol#L14, Fed.sol#L131, INVEscrow.sol#L10, INVEscrow.sol#L17, INVEscrow.sol#L79, GovTokenEscrow.sol#L9, GovTokenEscrow.sol#L66

Description: The best-practice layout for a contract should follow the following order: state variables, events, modifiers, constructor and functions. Function ordering helps readers identify which functions they can call and find constructor and fallback functions easier. Functions should be grouped according to their visibility and ordered as: constructor, receive function (if exists), fallback function (if exists), external, public, internal, private. Functions should then further be ordered with view functions coming after the non-view labeled ones.

Recommendation: Consider adopting recommended best-practice for code structure and layout.

[NAZ-N5] Use Underscores for Number Literals

Severity: Informational Context: Market.sol#L51, Market.sol#L74-L76, Market.sol#L150, Market.sol#L162, Market.sol#L173, Market.sol#L184, Market.sol#L195, Market.sol#L336, Market.sol#L346, Market.sol#L360, Market.sol#L377, Market.sol#L563-L564, Market.sol#L583, Market.sol#L595, Market.sol#L598, Market.sol#L606, DBR.sol#L330, Oracle.sol#L95, Oracle.sol#L98, Oracle.sol#L134, Oracle.sol#L137

Description: There are multiple occasions where certain numbers have been hardcoded, either in variables or in the code itself. Large numbers can become hard to read.

Recommendation: Consider using underscores for number literals to improve its readability.

[NAZ-N6] TODOs Left In The Code

Severity: Informational Context: INVEscrow.sol#L35

Description: There should never be any TODOs in the code when deploying.

Recommendation: Consider finishing the TODOs before deploying.

[NAZ-N7] Spelling Errors

Severity: Informational Context: Market.sol#L172 (setReplenismentIncentiveBps => setReplenishmentIncentiveBps), Market.sol#L181 (liqudation => liquidation), Market.sol#L578 (liquidateable => liquidatable), DBR.sol#L50 (oprator => operator), DBR.sol#L60 (replen => replenishment), DBR.sol#L87 (allowe => allow), DBR.sol#L96 (unrepayable => non-repayable), BorrowController.sol#L36 (addres => address)

Description: Spelling errors in comments can cause confusion to both users and developers.

Recommendation: Consider checking all misspellings to ensure they are corrected.

[NAZ-N8] Missing or Incomplete NatSpec

Severity: Informational Context: All Contracts

Description: Some functions are missing @notice/@dev NatSpec comments for the function, @param for all/some of their parameters and @return for return values. Given that NatSpec is an important part of code documentation, this affects code comprehension, auditability and usability.

Recommendation: Consider adding in full NatSpec comments for all functions to have complete code documentation for future use.

[NAZ-N9] Floating Pragma

Severity: Informational Context: All Contracts

Description: 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.

Recommendation: Consider locking the pragma version.

[NAZ-N10] Older Version Pragma

Severity: Informational Context: All Contracts

Description: Using very old versions of Solidity prevents benefits of bug fixes and newer security checks. Using the latest versions might make contracts susceptible to undiscovered compiler bugs.

Recommendation: Consider using the most recent version.