Contracts V2 Updates Audit | Moonwell

Summary

100% of all REPORTED Findings have been addressed

About this report

Assessment Type

Assurance Assessment

Date of Engagement

July 16th, 2023 - August 16th, 2023

Source Code

moonwell-contracts-v2

Assessed Commit ID

c39f98b

Severity Breakdown

6Acknowledged
1Risk Accepted
14Solved
21All Findings

Critical0
High2
- 2Solved
Medium3
- 3Solved
Low5
- 4Solved
- 1Risk A.
Informational11
- 5Solved
- 6Ack.

Risk Methodology#

Every vulnerability and issue observed by Halborn is ranked based on two sets of Metrics and a Severity Coefficient. This system is inspired by the industry standard Common Vulnerability Scoring System.

The two Metric sets are: Exploitability and Impact. Exploitability captures the ease and technical means by which vulnerabilities can be exploited and Impact describes the consequences of a successful exploit.

The Severity Coefficients is designed to further refine the accuracy of the ranking with two factors: Reversibility and Scope. These capture the impact of the vulnerability on the environment as well as the number of users and smart contracts affected.

The final score is a value between 0-10 rounded up to 1 decimal place and 10 corresponding to the highest security risk. This provides an objective and accurate rating of the severity of security vulnerabilities in smart contracts.

The system is designed to assist in identifying and prioritizing vulnerabilities based on their level of risk to address the most critical issues in a timely manner.

1.1 EXPLOITABILITY

Attack Origin (AO):

Captures whether the attack requires compromising a specific account.

Attack Cost (AC):

Captures the cost of exploiting the vulnerability incurred by the attacker relative to sending a single transaction on the relevant blockchain. Includes but is not limited to financial and computational cost.

Attack Complexity (AX):

Describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. Includes but is not limited to macro situation, available third-party liquidity and regulatory challenges.

Metrics:

EXPLOITABILITY METRIC ( $m_e$ )	METRIC VALUE	NUMERICAL VALUE
Attack Origin (AO)	Arbitrary (AO:A)	1
Attack Origin (AO)	Specific (AO:S)	0.2
Attack Cost (AC)	Low (AC:L)	1
	Medium (AC:M)	0.67
	High (AC:H)	0.33
Attack Complexity (AX)	Low (AX:L)	1
	Medium (AX:M)	0.67
	High (AX:H)	0.33

Exploitability

E

is calculated using the following formula:

$E = \prod m_e$

1.2 IMPACT

Confidentiality (C):

Measures the impact to the confidentiality of the information resources managed by the contract due to a successfully exploited vulnerability. Confidentiality refers to limiting access to authorized users only.

Integrity (I):

Measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of data stored and/or processed on-chain. Integrity impact directly affecting Deposit or Yield records is excluded.

Availability (A):

Measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. This metric refers to smart contract features and functionality, not state. Availability impact directly affecting Deposit or Yield is excluded.

Deposit (D):

Measures the impact to the deposits made to the contract by either users or owners.

Yield (Y):

Measures the impact to the yield generated by the contract for either users or owners.

Metrics:

IMPACT METRIC ( $m_I$ )	METRIC VALUE	NUMERICAL VALUE
Confidentiality (C)	None (C:N)	0
	Low (C:L)	0.25
	Medium (C:M)	0.5
	High (C:H)	0.75
	Critical (C:C)	1
Integrity (I)	None (I:N)	0
	Low (I:L)	0.25
	Medium (I:M)	0.5
	High (I:H)	0.75
	Critical (I:C)	1
Availability (A)	None (A:N)	0
	Low (A:L)	0.25
	Medium (A:M)	0.5
	High (A:H)	0.75
	Critical (A:C)	1
Deposit (D)	None (D:N)	0
	Low (D:L)	0.25
	Medium (D:M)	0.5
	High (D:H)	0.75
	Critical (D:C)	1
Yield (Y)	None (Y:N)	0
	Low (Y:L)	0.25
	Medium (Y:M)	0.5
	High (Y:H)	0.75
	Critical (Y:C)	1

Impact

I

is calculated using the following formula:

$I = max(m_I) + \frac{\sum{m_I} - max(m_I)}{4}$

1.3 SEVERITY COEFFICIENT

Reversibility (R):

Describes the share of the exploited vulnerability effects that can be reversed. For upgradeable contracts, assume the contract private key is available.

Scope (S):

Captures whether a vulnerability in one vulnerable contract impacts resources in other contracts.

Metrics:

SEVERITY COEFFICIENT ( $C$ )	COEFFICIENT VALUE	NUMERICAL VALUE
Reversibility ( $r$ )	None (R:N)	1
	Partial (R:P)	0.5
	Full (R:F)	0.25
Scope ( $s$ )	Changed (S:C)	1.25
Scope ( $s$ )	Unchanged (S:U)	1

Severity Coefficient

C

is obtained by the following product:

$C = rs$

The Vulnerability Severity Score

S

is obtained by:

$S = min(10, EIC * 10)$

The score is rounded up to 1 decimal places.

Critical	High	Medium	Low	Informational
9 - 10	7 - 8.9	4.5 - 6.9	2 - 4.4	0 - 1.9

Scope#

(a) Repository:moonwell-contracts-v2

(b) Assessed Commit ID:c39f98bdc9dd4e448ba585923034af1d47f74dfa

11 files

ChainlinkCompositeOracle.sol

solidity

ChainlinkOracle.sol

solidity

mip-b00.sol

solidity

mip-m23.sol

solidity

mip-m24.sol

solidity

MultiRewardDistributor.sol

solidity

MWethDelegate.sol

solidity

TemporalGovernor.sol

solidity

WETHRouter.sol

solidity

Additional scope:08b984680f722fca1c60aab27a7a2715877638a7,59cf6af16aaa46c1805fdafeb93aa527883ba3f1

Out-of-Scope: New features/implementations after the remediation commit IDs.

Assessment Summary & Findings Overview#

#	Title	Severity	Score	Status
HAL-01	SILENT FAILURE DURING TOKEN MINTING ON THE ROUTER CONTRACT	High	8.2	Solved07/22/2023
HAL-02	SILENT FAILURE DURING TOKEN REDEMPTION ON THE ROUTER CONTRACT	High	8.2	Solved07/22/2023
HAL-03	MINT WITH PERMIT CAN BE BROKEN WHEN USING TOKENS THAT DO NOT FOLLOW THE ERC2612 STANDARD	Medium	6.7	Solved07/27/2023
HAL-04	LACK OF END TIME VALIDATION LEADS TO WRONG MARKET INDEX CALCULATION ON THE NEW MARKETS	Medium	6.3	Solved07/27/2023
HAL-05	MISSING CHAIN ID AND RECEIVER ADDRESS VERIFICATION IN EXECUTEPROPOSAL() FUNCTION	Medium	5.9	Solved07/22/2023
HAL-06	WRONG EVENT IS EMITTED IN THE UPDATE BORROW SPEED FUNCTION	Low	3.4	Solved07/27/2023
HAL-07	EMISSIONCAP LACKS AN UPPER BOUND, LEADING TO POTENTIAL OVERFLOWS	Low	3.4	Risk Accepted
HAL-08	UNRESTRICTED RECEIVE IN WETHROUTER ENABLES EXCESS REDEMPTIONS	Low	3.1	Solved07/22/2023
HAL-09	IMPLEMENTATIONS CAN BE INITIALIZED	Low	2.5	Solved07/19/2023
HAL-10	HARD-CODED MTOKEN ADDRESS IN WETHUNWRAPPER CONTRACT	Low	2.5	Solved08/15/2023
HAL-11	EVENT IS MISSING INDEXED FIELDS	Informational	0.0	Solved07/27/2023
HAL-12	FLOATING PRAGMA	Informational	0.0	Solved07/23/2023
HAL-13	USE CUSTOM ERRORS INSTEAD OF REVERT STRINGS TO SAVE GAS	Informational	0.0	Acknowledged
HAL-14	INCREMENT/DECREMENT FOR LOOP VARIABLE IN AN UNCHECKED BLOCK	Informational	0.0	Acknowledged
HAL-15	LACK OF A DOUBLE-STEP TRANSFEROWNERSHIP PATTERN	Informational	0.0	Acknowledged
HAL-16	CACHE ARRAY LENGTH	Informational	0.0	Acknowledged
HAL-17	REDUNDANT SAFE CAST	Informational	0.0	Solved07/23/2023
HAL-18	REVERT STRING SIZE OPTIMIZATION	Informational	0.0	Acknowledged
HAL-19	NO NEED TO INITIALIZE VARIABLES WITH DEFAULT VALUES	Informational	0.0	Acknowledged
HAL-20	RETURN VALUE NOT STORED	Informational	0.0	Solved07/27/2023
HAL-21	REQUIRE() / REVERT() STATEMENTS SHOULD HAVE DESCRIPTIVE REASON STRINGS	Informational	0.0	Solved07/27/2023

Findings & Tech Details#

HAL-01Solved

SILENT FAILURE DURING TOKEN MINTING ON THE ROUTER CONTRACT

High

8.2AO:A/AC:L/AX:L/C:N/I:H/A:H/D:H/Y:H/R:P/S:CAO:A/AC:L/AX:L/C:N/I:H/A:H/D:H/Y:H/R:P/S:C

Description

Proof of Concept

Recommendation

HAL-02Solved

SILENT FAILURE DURING TOKEN REDEMPTION ON THE ROUTER CONTRACT

High

8.2AO:A/AC:L/AX:L/C:N/I:H/A:H/D:H/Y:H/R:P/S:CAO:A/AC:L/AX:L/C:N/I:H/A:H/D:H/Y:H/R:P/S:C

Description

Proof of Concept

Recommendation

HAL-03Solved

MINT WITH PERMIT CAN BE BROKEN WHEN USING TOKENS THAT DO NOT FOLLOW THE ERC2612 STANDARD

Medium

6.7AO:A/AC:M/AX:M/C:L/I:C/A:N/D:L/Y:L/R:N/S:CAO:A/AC:M/AX:M/C:L/I:C/A:N/D:L/Y:L/R:N/S:C

Description

Proof of Concept

Recommendation

HAL-04Solved

LACK OF END TIME VALIDATION LEADS TO WRONG MARKET INDEX CALCULATION ON THE NEW MARKETS

Medium

6.3AO:A/AC:L/AX:L/C:M/I:M/A:L/D:H/Y:H/R:P/S:UAO:A/AC:L/AX:L/C:M/I:M/A:L/D:H/Y:H/R:P/S:U

Description

Proof of Concept

Recommendation

HAL-05Solved

MISSING CHAIN ID AND RECEIVER ADDRESS VERIFICATION IN EXECUTEPROPOSAL() FUNCTION

Medium

5.9AO:A/AC:L/AX:L/C:N/I:H/A:H/D:N/Y:N/R:P/S:CAO:A/AC:L/AX:L/C:N/I:H/A:H/D:N/Y:N/R:P/S:C

Description

Proof of Concept

Recommendation

HAL-06Solved

WRONG EVENT IS EMITTED IN THE UPDATE BORROW SPEED FUNCTION

Low

3.4AO:A/AC:L/AX:L/C:M/I:M/A:L/D:N/Y:N/R:P/S:UAO:A/AC:L/AX:L/C:M/I:M/A:L/D:N/Y:N/R:P/S:U

Description

Recommendation

HAL-07Risk Accepted

EMISSIONCAP LACKS AN UPPER BOUND, LEADING TO POTENTIAL OVERFLOWS

Low

3.4AO:A/AC:L/AX:L/C:M/I:M/A:L/D:N/Y:N/R:P/S:UAO:A/AC:L/AX:L/C:M/I:M/A:L/D:N/Y:N/R:P/S:U

Description

Recommendation

HAL-08Solved

UNRESTRICTED RECEIVE IN WETHROUTER ENABLES EXCESS REDEMPTIONS

Low

3.1AO:A/AC:L/AX:L/C:N/I:N/A:N/D:M/Y:N/R:P/S:CAO:A/AC:L/AX:L/C:N/I:N/A:N/D:M/Y:N/R:P/S:C

Description

Recommendation

HAL-09Solved

IMPLEMENTATIONS CAN BE INITIALIZED

Low

2.5AO:A/AC:L/AX:M/C:N/I:L/A:N/D:L/Y:L/R:N/S:UAO:A/AC:L/AX:M/C:N/I:L/A:N/D:L/Y:L/R:N/S:U

Description

Recommendation

HAL-10Solved

HARD-CODED MTOKEN ADDRESS IN WETHUNWRAPPER CONTRACT

Low

2.5AO:A/AC:L/AX:M/C:N/I:L/A:N/D:L/Y:L/R:N/S:UAO:A/AC:L/AX:M/C:N/I:L/A:N/D:L/Y:L/R:N/S:U

Description

Recommendation

HAL-11Solved

EVENT IS MISSING INDEXED FIELDS

Informational

0.0AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:CAO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:C

Description

Recommendation

HAL-12Solved

FLOATING PRAGMA

Informational

0.0AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:N/S:CAO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:N/S:C

Description

Recommendation

HAL-13Acknowledged

USE CUSTOM ERRORS INSTEAD OF REVERT STRINGS TO SAVE GAS

Informational

0.0AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:N/S:CAO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:N/S:C

Description

Recommendation

HAL-14Acknowledged

INCREMENT/DECREMENT FOR LOOP VARIABLE IN AN UNCHECKED BLOCK

Informational

0.0AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:N/S:CAO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:N/S:C

Description

Recommendation

HAL-15Acknowledged

LACK OF A DOUBLE-STEP TRANSFEROWNERSHIP PATTERN

Informational

0.0AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:CAO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:C

Description

Recommendation

HAL-16Acknowledged

CACHE ARRAY LENGTH

Informational

0.0AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:CAO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:C

Description

Recommendation

HAL-17Solved

REDUNDANT SAFE CAST

Informational

0.0AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:CAO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:C

Description

Recommendation

HAL-18Acknowledged

REVERT STRING SIZE OPTIMIZATION

Informational

0.0AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:CAO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:C

Description

Recommendation

HAL-19Acknowledged

NO NEED TO INITIALIZE VARIABLES WITH DEFAULT VALUES

Informational

0.0AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:CAO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:C

Description

Recommendation

HAL-20Solved

RETURN VALUE NOT STORED

Informational

0.0AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:CAO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:C

Description

Recommendation

HAL-21Solved

REQUIRE() / REVERT() STATEMENTS SHOULD HAVE DESCRIPTIVE REASON STRINGS

Informational

0.0AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:CAO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:C

Description

Recommendation

5. Automated Testing#

Disclaimer#

Halborn strongly recommends conducting a follow-up assessment of the project either within six months or immediately following any material changes to the codebase, whichever comes first. This approach is crucial for maintaining the project’s integrity and addressing potential vulnerabilities introduced by code modifications.