Storage Proofs

Summary

The verifyScrvusdByStateRoot function in ScrvusdVerifierV1 trusts the blockhash oracle’s state root without validation, unlike verifyScrvusdByBlockHash. This partial mitigation relies on oracle reliability, leaving a gap if it fails.

Vulnerability Details

The vulnerable code is in verifyScrvusdByStateRoot:

• Blind Trust: No check against blockhash, unlike:

  require(block_header.hash == IBlockHashOracle(BLOCK_HASH_ORACLE).get_block_hash(block_header.number));

PoC

Objective

Feed a fake state root via a compromised blockhash oracle to misprice scrvUSD.

Prerequisites

• Deployed ScrvusdVerifierV1 with a mock IBlockHashOracle.

• Control over the oracle’s state root return value (test setup).

Exploit Scenario

An attacker uses a rigged blockhash oracle to supply a fake state root, passing invalid parameters.

Proof of Concept Steps

1. Mock Oracle:

   solidity

   contract MockBlockHashOracle {

   function get_block_hash(uint256) external pure returns (bytes32) { return bytes32(0x123); }

   function get_state_root(uint256) external pure returns (bytes32) { return bytes32(0xdead); } // Fake root

   }

2. Setup: Deploy ScrvusdVerifierV1 with MockBlockHashOracle.

3. Exploit:

   • Craft a proof matching the fake state root 0xdead with skewed parameters (e.g., total_debt = 1000000).

   • Call verifyScrvusdByStateRoot(blockNumber, proof_rlp).

4. Result: Oracle updates with inflated price, exploitable in pools.

Outcome

Proves reliance on oracle trust can lead to catastrophic mispricing.

Notes

• These PoCs assume testnet control (e.g., role access, mock dependencies). In a live environment, exploits depend on compromising roles or oracles.

• For a real contest, you’d deploy these on a fork (e.g., Foundry/Anvil) and log results (e.g., price changes, reverts).

Impact

Garbage Data: Incorrect state root feeds invalid parameters, mispricing scrvUSD.

• Pool Exploit: Temporary mispricing could drain pools.

Tools Used

Manual Review

Recommendations

Cross-verify state root with blockhash in verifyScrvusdByStateRoot (requires block header input):