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Submission Details
Severity: high
Invalid

Incorrect Slot Lookup in ScrvusdVerifierV1.sol

dreamcoder

Summary

In ScrvusdVerifierV1.sol file

PARAM_SLOTS is defined with incorrect slot lookup.

Vulnerability Details

In ScrvusdVerifierV1.sol file

uint256[PROOF_CNT] internal PARAM_SLOTS = [
uint256(0), // filler for account proof
uint256(21), // total_debt
uint256(22), // total_idle
uint256(20), // totalSupply
uint256(38), // full_profit_unlock_date
uint256(39), // profit_unlocking_rate
uint256(40), // last_profit_update
uint256(keccak256(abi.encode(18, SCRVUSD))) // balanceOf(self)
];

In uint256(keccak256(abi.encode(18, SCRVUSD)))

Solidity computes the storage slot of balanceOf[address] as:

keccak256(abi.encode(address, slot_index))

But in the contract, used keccak256(abi.encode(slot_index, address))

Impact

The extracted value for balanceOf(SCRVUSD) is incorrect.

This incorrect value is passed to the IScrvusdOracle.update_price() function, leading to:

  • Incorrect price calculations.

  • Potential manipulation of the scrvUSD price.

Tools Used

Manual

Recommendations

Need to modify as following.

uint256(keccak256(abi.encode(SCRVUSD, 18)))

Updates

Lead Judging Commences

0xnevi Lead Judge 10 months ago
Submission Judgement Published
Invalidated
Reason: Incorrect statement
Assigned finding tags:

[invalid] finding-ScrvusdVerifierV1-incorrect-storage-slot-balanceOf-compute

- Per sponsor comments, verified slot is vyper, solidity contract only verifies it. - Vyper computes storage slots different from solidity as seen [here](https://ethereum.stackexchange.com/questions/149311/storage-collision-in-vyper-hashmap)

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