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Background

// Security Assessment

07.16.2023 - 08.16.2023

Contracts V2 Updates

Moonwell

Halborn logotext
← Back to Audits

Contracts V2 Updates - Moonwell

Prepared by:

Halborn Logo

HALBORN

Last Updated Unknown date

Date of Engagement: July 16th, 2023 - August 16th, 2023

Summary

100% of all REPORTED Findings have been addressed

All findings

21

Critical

0

High

2

Medium

3

Low

5

Informational

11

Table of Contents

  • 1. Risk methodology
  • 2. Scope
  • 3. Assessment summary & findings overview
  • 4. Findings & Tech Details
    1. 4.1 Silent failure during token minting on the router contract
    2. 4.2 Silent failure during token redemption on the router contract
    3. 4.3 Mint with permit can be broken when using tokens that do not follow the erc2612 standard
    4. 4.4 Lack of end time validation leads to wrong market index calculation on the new markets
    5. 4.5 Missing chain id and receiver address verification in executeproposal() function
    6. 4.6 Wrong event is emitted in the update borrow speed function
    7. 4.7 Emissioncap lacks an upper bound, leading to potential overflows
    8. 4.8 Unrestricted receive in wethrouter enables excess redemptions
    9. 4.9 Implementations can be initialized
    10. 4.10 Hard-coded mtoken address in wethunwrapper contract
    11. 4.11 Event is missing indexed fields
    12. 4.12 Floating pragma
    13. 4.13 Use custom errors instead of revert strings to save gas
    14. 4.14 Increment/decrement for loop variable in an unchecked block
    15. 4.15 Lack of a double-step transferownership pattern
    16. 4.16 Cache array length
    17. 4.17 Redundant safe cast
    18. 4.18 Revert string size optimization
    19. 4.19 No need to initialize variables with default values
    20. 4.20 Return value not stored
    21. 4.21 Require() / revert() statements should have descriptive reason strings
  • 5. Automated Testing

1. 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 (mem_eme​)METRIC VALUENUMERICAL VALUE
Attack Origin (AO)Arbitrary (AO:A)
Specific (AO:S)		1
0.2
Attack Cost (AC)Low (AC:L)
Medium (AC:M)
High (AC:H)		1
0.67
0.33
Attack Complexity (AX)Low (AX:L)
Medium (AX:M)
High (AX:H)		1
0.67
0.33
Exploitability EEE is calculated using the following formula:

E=∏meE = \prod m_eE=∏me​

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 (mIm_ImI​)METRIC VALUENUMERICAL VALUE
Confidentiality (C)None (C:N)
Low (C:L)
Medium (C:M)
High (C:H)
Critical (C:C)		0
0.25
0.5
0.75
1
Integrity (I)None (I:N)
Low (I:L)
Medium (I:M)
High (I:H)
Critical (I:C)		0
0.25
0.5
0.75
1
Availability (A)None (A:N)
Low (A:L)
Medium (A:M)
High (A:H)
Critical (A:C)		0
0.25
0.5
0.75
1
Deposit (D)None (D:N)
Low (D:L)
Medium (D:M)
High (D:H)
Critical (D:C)		0
0.25
0.5
0.75
1
Yield (Y)None (Y:N)
Low (Y:L)
Medium (Y:M)
High (Y:H)
Critical (Y:C)		0
0.25
0.5
0.75
1
Impact III is calculated using the following formula:

I=max(mI)+∑mI−max(mI)4I = max(m_I) + \frac{\sum{m_I} - max(m_I)}{4}I=max(mI​)+4∑mI​−max(mI​)​

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 (CCC)COEFFICIENT VALUENUMERICAL VALUE
Reversibility (rrr)None (R:N)
Partial (R:P)
Full (R:F)		1
0.5
0.25
Scope (sss)Changed (S:C)
Unchanged (S:U)		1.25
1
Severity Coefficient CCC is obtained by the following product:

C=rsC = rsC=rs

The Vulnerability Severity Score SSS is obtained by:

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

The score is rounded up to 1 decimal places.
SeverityScore Value Range
Critical9 - 10
High7 - 8.9
Medium4.5 - 6.9
Low2 - 4.4
Informational0 - 1.9

2. SCOPE

REPOSITORY
(a) Repository: moonwell-contracts-v2
(b) Assessed Commit ID: c39f98b
(c) Items in scope:
  • MultiRewardDistributor.sol
  • WETHRouter.sol
  • TemporalGovernor.sol
  • ChainlinkCompositeOracle.sol
  • ChainlinkOracle.sol
  • MWethDelegate.sol
  • MWethDelegate.sol
  • WETHRouter.sol
  • mip-b00.sol
  • mip-m23.sol
  • mip-m24.sol
  • moonwell-fi/moonwell-contracts-v2/commit/08b984680f722fca1c60aab27a7a2715877638a7
  • moonwell-fi/moonwell-contracts-v2/commit/59cf6af16aaa46c1805fdafeb93aa527883ba3f1
  • MultiRewardDistributor.sol
  • WETHRouter.sol
  • TemporalGovernor.sol
↓ Expand ↓
Out-of-Scope: New features/implementations after the remediation commit IDs.

3. Assessment Summary & Findings Overview

Critical

0

High

2

Medium

3

Low

5

Informational

11

Security analysisRisk levelRemediation Date
SILENT FAILURE DURING TOKEN MINTING ON THE ROUTER CONTRACTHighSolved - 07/22/2023
SILENT FAILURE DURING TOKEN REDEMPTION ON THE ROUTER CONTRACTHighSolved - 07/22/2023
MINT WITH PERMIT CAN BE BROKEN WHEN USING TOKENS THAT DO NOT FOLLOW THE ERC2612 STANDARDMediumSolved - 07/27/2023
LACK OF END TIME VALIDATION LEADS TO WRONG MARKET INDEX CALCULATION ON THE NEW MARKETSMediumSolved - 07/27/2023
MISSING CHAIN ID AND RECEIVER ADDRESS VERIFICATION IN EXECUTEPROPOSAL() FUNCTIONMediumSolved - 07/22/2023
WRONG EVENT IS EMITTED IN THE UPDATE BORROW SPEED FUNCTIONLowSolved - 07/27/2023
EMISSIONCAP LACKS AN UPPER BOUND, LEADING TO POTENTIAL OVERFLOWSLowRisk Accepted
UNRESTRICTED RECEIVE IN WETHROUTER ENABLES EXCESS REDEMPTIONSLowSolved - 07/22/2023
IMPLEMENTATIONS CAN BE INITIALIZEDLowSolved - 07/19/2023
HARD-CODED MTOKEN ADDRESS IN WETHUNWRAPPER CONTRACTLowSolved - 08/15/2023
EVENT IS MISSING INDEXED FIELDSInformationalSolved - 07/27/2023
FLOATING PRAGMAInformationalSolved - 07/23/2023
USE CUSTOM ERRORS INSTEAD OF REVERT STRINGS TO SAVE GASInformationalAcknowledged
INCREMENT/DECREMENT FOR LOOP VARIABLE IN AN UNCHECKED BLOCKInformationalAcknowledged
LACK OF A DOUBLE-STEP TRANSFEROWNERSHIP PATTERNInformationalAcknowledged
CACHE ARRAY LENGTHInformationalAcknowledged
REDUNDANT SAFE CASTInformationalSolved - 07/23/2023
REVERT STRING SIZE OPTIMIZATIONInformationalAcknowledged
NO NEED TO INITIALIZE VARIABLES WITH DEFAULT VALUESInformationalAcknowledged
RETURN VALUE NOT STOREDInformationalSolved - 07/27/2023
REQUIRE() / REVERT() STATEMENTS SHOULD HAVE DESCRIPTIVE REASON STRINGSInformationalSolved - 07/27/2023

4. Findings & Tech Details

4.1 SILENT FAILURE DURING TOKEN MINTING ON THE ROUTER CONTRACT

//

High

Description
Proof of Concept
BVSS
AO:A/AC:L/AX:L/C:N/I:H/A:H/D:H/Y:H/R:P/S:C (8.2)
Recommendation

4.2 SILENT FAILURE DURING TOKEN REDEMPTION ON THE ROUTER CONTRACT

//

High

Description
Proof of Concept
BVSS
AO:A/AC:L/AX:L/C:N/I:H/A:H/D:H/Y:H/R:P/S:C (8.2)
Recommendation

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

//

Medium

Description
Proof of Concept
BVSS
AO:A/AC:M/AX:M/C:L/I:C/A:N/D:L/Y:L/R:N/S:C (6.7)
Recommendation

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

//

Medium

Description
Proof of Concept
BVSS
AO:A/AC:L/AX:L/C:M/I:M/A:L/D:H/Y:H/R:P/S:U (6.3)
Recommendation

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

//

Medium

Description
Proof of Concept
BVSS
AO:A/AC:L/AX:L/C:N/I:H/A:H/D:N/Y:N/R:P/S:C (5.9)
Recommendation

4.6 WRONG EVENT IS EMITTED IN THE UPDATE BORROW SPEED FUNCTION

//

Low

Description
BVSS
AO:A/AC:L/AX:L/C:M/I:M/A:L/D:N/Y:N/R:P/S:U (3.4)
Recommendation

4.7 EMISSIONCAP LACKS AN UPPER BOUND, LEADING TO POTENTIAL OVERFLOWS

//

Low

Description
BVSS
AO:A/AC:L/AX:L/C:M/I:M/A:L/D:N/Y:N/R:P/S:U (3.4)
Recommendation

4.8 UNRESTRICTED RECEIVE IN WETHROUTER ENABLES EXCESS REDEMPTIONS

//

Low

Description
BVSS
AO:A/AC:L/AX:L/C:N/I:N/A:N/D:M/Y:N/R:P/S:C (3.1)
Recommendation

4.9 IMPLEMENTATIONS CAN BE INITIALIZED

//

Low

Description
BVSS
AO:A/AC:L/AX:M/C:N/I:L/A:N/D:L/Y:L/R:N/S:U (2.5)
Recommendation

4.10 HARD-CODED MTOKEN ADDRESS IN WETHUNWRAPPER CONTRACT

//

Low

Description
BVSS
AO:A/AC:L/AX:M/C:N/I:L/A:N/D:L/Y:L/R:N/S:U (2.5)
Recommendation

4.11 EVENT IS MISSING INDEXED FIELDS

//

Informational

Description
BVSS
AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:C (0.0)
Recommendation

4.12 FLOATING PRAGMA

//

Informational

Description
BVSS
AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:N/S:C (0.0)
Recommendation

4.13 USE CUSTOM ERRORS INSTEAD OF REVERT STRINGS TO SAVE GAS

//

Informational

Description
BVSS
AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:N/S:C (0.0)
Recommendation

4.14 INCREMENT/DECREMENT FOR LOOP VARIABLE IN AN UNCHECKED BLOCK

//

Informational

Description
BVSS
AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:N/S:C (0.0)
Recommendation

4.15 LACK OF A DOUBLE-STEP TRANSFEROWNERSHIP PATTERN

//

Informational

Description
BVSS
AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:C (0.0)
Recommendation

4.16 CACHE ARRAY LENGTH

//

Informational

Description
BVSS
AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:C (0.0)
Recommendation

4.17 REDUNDANT SAFE CAST

//

Informational

Description
BVSS
AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:C (0.0)
Recommendation

4.18 REVERT STRING SIZE OPTIMIZATION

//

Informational

Description
BVSS
AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:C (0.0)
Recommendation

4.19 NO NEED TO INITIALIZE VARIABLES WITH DEFAULT VALUES

//

Informational

Description
BVSS
AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:C (0.0)
Recommendation

4.20 RETURN VALUE NOT STORED

//

Informational

Description
BVSS
AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:C (0.0)
Recommendation

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

//

Informational

Description
BVSS
AO:A/AC:L/AX:L/C:N/I:N/A:N/D:N/Y:N/R:F/S:C (0.0)
Recommendation

5. Automated Testing

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.

Table of Contents

  • 1. Risk methodology
  • 2. Scope
  • 3. Assessment summary & findings overview
  • 4. Findings & Tech Details
    1. 4.1 Silent failure during token minting on the router contract
    2. 4.2 Silent failure during token redemption on the router contract
    3. 4.3 Mint with permit can be broken when using tokens that do not follow the erc2612 standard
    4. 4.4 Lack of end time validation leads to wrong market index calculation on the new markets
    5. 4.5 Missing chain id and receiver address verification in executeproposal() function
    6. 4.6 Wrong event is emitted in the update borrow speed function
    7. 4.7 Emissioncap lacks an upper bound, leading to potential overflows
    8. 4.8 Unrestricted receive in wethrouter enables excess redemptions
    9. 4.9 Implementations can be initialized
    10. 4.10 Hard-coded mtoken address in wethunwrapper contract
    11. 4.11 Event is missing indexed fields
    12. 4.12 Floating pragma
    13. 4.13 Use custom errors instead of revert strings to save gas
    14. 4.14 Increment/decrement for loop variable in an unchecked block
    15. 4.15 Lack of a double-step transferownership pattern
    16. 4.16 Cache array length
    17. 4.17 Redundant safe cast
    18. 4.18 Revert string size optimization
    19. 4.19 No need to initialize variables with default values
    20. 4.20 Return value not stored
    21. 4.21 Require() / revert() statements should have descriptive reason strings
  • 5. Automated Testing

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