Techniques have been developed whereby dynamic kernel/user-level tracing may be employed to efficiently characterize runtime behavior of production code. Using dynamic tracing techniques, user space or kernel instruction sequences between system calls may be instrumented without access to source code. In some realizations, instrumentation may be interactively specified on a host system. In some realizations, instrumentation specifications may be supplied as functional definitions (e.g., as scripts and/or probe definitions) for installation on a host system. Using the developed techniques, data states, parameters passed and/or timing information may be sampled to provide more detailed insight into actual program behavior. In signature-oriented exploitations, more powerful intrusion signatures are possible. In anomaly-oriented exploitations, a more detailed “sense of self” may be developed to discriminate between normal and anomalous program behavior.