Hypernative Firewall is an onchain contract-based security solution designed to prevent malicious blockchain interactions without pausing entire protocols. The firewall operates as a policy enforcer that validates transactions before execution, allowing legitimate users to continue operations while blocking attackers. The solution performs multiple security checks including execution logic analysis to determine if interactions will result in exploits, transaction parameter examination to prevent malicious frontend interactions, flagging contracts or wallets with past involvement in malicious activities, verification against government and organizational sanction lists such as OFAC, and validation against client-defined allow and block lists. The firewall integrates with Hypernative's detection engine suite to assess unknown addresses before their first interaction with a protocol. When a protected contract queries the onchain oracle through the Hypernative SDK, the system evaluates the address and either permits legitimate interactions or denies potentially malicious ones. The solution addresses flash exploits where contract deployment and exploitation occur within a single transaction. It uses machine learning-powered checks while maintaining low gas costs of approximately 7,000 gas per transaction. Implementation requires minimal code changes to existing smart contracts.