A system for protecting an electronic device against malware includes a memory, an operating system configured to execute on the electronic device, and a below-operating-system security agent. The below-operating-system security agent is configured to trap an attempted access of a resource of the electronic device, access one or more security rules to determine whether the attempted access is indicative of malware, and operate at a level below all of the operating systems of the electronic device accessing the memory. The attempted access includes attempting to write instructions to the memory and attempting to execute the instructions.