It would be interesting to consider capturing the set of rules, heuristics, etc. that triggered during the analysis of a malware instance. For example, this could include the Yara rules, Cuckoo sandbox rules, and the like.
We probably don't want to capture the actual rule itself, since that could be done elsewhere (like the STIX Indicator), but instead we may just want something that captures the type of rule (Yara, etc.) and its identifier/name.