A candidate signature for a known malware entity is selected for analysis. A set of malware entities that contain the candidate signature is identified. A diversity measurement for the candidate signature is determined. The diversity measurement describes the diversity of the set of malware entities that contain the candidate signature. A determination is made whether to use the candidate signature to identify the known malware entity based at least in part on the diversity measurement. Responsive to the determination, the candidate malware signature is stored as a signature for the known malware entity.