A method and apparatus for injecting function calls into a virtual machine whereby a Function Call Injection (FCI) process is employed, through which a Secure Virtual Machine (SVM) is used to trigger desired function call invocations inside a Guest Virtual Machine (GVM) by externally manipulating the GVMs memory and CPU register contents using a security API. Once the triggered function is executed, control is then returned at the originating SVM invocation point. Therefore, the GVM state is manipulated to externally inject function calls, making it possible to create control appliances which do not require an in-GVM agent.