Method and system for detecting and countering malware in a computer

An arrangement analyzes a data stream to identify particular token sequences known to be of interest or malware. A preprocessing step organizes the malware tokens into a "graph" in which overlapping token sequences are interconnected with logic splices. The preprocessing is performed only once for a given set of malware targets. The resulting graph can be traversed quickly in runtime operation to identify malware token strings in the data stream.