Paxos

1 Executive Summary

In November 2020, we conducted a security assessment of Paxos’s multisig wallet contract. This wallet is based on Christian Lundkvist’s SimpleMultiSig contract, which we previously reviewed.

Paxos’s modification allows the set of owners to be changed after the wallet is deployed. This report focuses on the impact of those changes.

We performed this assessment between November 7th and November 10th, 2020. The engagement was primarily conducted by Steve Marx. The total effort expended was 8 person-hours.

1.1 Scope

2 Recommendations

bytes32 DOMAIN_SEPARATOR;          // hash for EIP712, computed from contract address

// If we make it here all signatures are accounted for.
// The address.call() syntax is no longer recommended, see:
// https://github.com/ethereum/solidity/issues/2884
nonce = nonce + 1;
bool success = false;
assembly { success := call(gasLimit, destination, value, add(data, 0x20), mload(data), 0, 0) }

mapping (address => bool) isOwner; // immutable state
address[] public ownersArr;        // immutable state

3 Findings

Each issue has an assigned severity:

• Minor issues are subjective in nature. They are typically suggestions around best practices or readability. Code maintainers should use their own judgment as to whether to address such issues.
• Medium issues are objective in nature but are not security vulnerabilities. These should be addressed unless there is a clear reason not to.
• Major issues are security vulnerabilities that may not be directly exploitable or may require certain conditions in order to be exploited. All major issues should be addressed.
• Critical issues are directly exploitable security vulnerabilities that need to be fixed.

for (uint256 i = 0; i < ownersArr.length; i++) {
   isOwner[ownersArr[i]] = false;
}

Appendix 1 - Disclosure

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