If a validator is compromised, a race condition in the signature validator approval logic becomes exploitable.
The setSignatureValidatorApproval function (Figure 4.1) allows users to delegate the signature validation to a contract.
However, if the validator is compromised, a race condition in this function could allow an attacker to validate any amount of malicious transactions.
Short term, document this behavior to make sure users are aware of the inherent risks of using validators in case of a compromise. Long term, consider monitoring the blockchain using the SignatureValidatorApproval events to catch front-running attacks.
- ToB Audit Ox Protocol Finding 4
- Timing
- Medium Severity
- Compromised Validator
- Sig Validation Race
- Document
- Monitor for Front-running
- Youtube Reference
- Medium Risk severity finding from ToB’s Audit of 0x Protocol