Described systems and methods allow protecting a computer system from malicious software. In some embodiments, a security application organizes a set of monitored executable entities (e.g., processes) into a plurality of groups, wherein members of a group are related by filiation and/or code injection. The security application may further associate a malice-indicative entity score with each monitored entity, and a malice-indicative group score with each entity group. Group scores may be incremented when a member of the respective group performs certain actions. Thus, even though actions performed by individual members may not be malware-indicative per se, the respective group score may capture collective malicious behavior and trigger malware detection.