The present system and method allow for preemptive, self-healing computer security. The system includes a user device processor and a PSS server processor. The two processors perform an initial Data Structure & Key Mutation (DSKM) method and an interval DSKM method at a given interval to protect secret information and prevent its exposure by attackers. When a user requests a site or service that is an attractive target for attackers, such as a bank site or monetary transfer service, the processors perform a Man in the Browser attack prevention method. When a packet is received or generated, the processors perform a Deep Protocol and Stateful Inspection and Prevention method to prevent receipt of malicious packets or the loss of sensitive information. Various forensics modules allow accurate forensic examination of the type, scope, and method of attack, as well as real-time protection of cloud-based services.