A server provides a reduced set of malware signatures to clients. The reduced set of malware signatures has the same scope of coverage as a comprehensive set of malware signatures stored on the server, but with a higher rate of false positive detections. The server receives signature detection event reports from the clients. A signature detection event report identifies the signature in the reduced set that was detected, and includes information describing the suspicious entity in which the signature was detected. Upon receiving a signature detection event report from a client, the server evaluates the information describing the suspicious entity using one or more signatures in the comprehensive set to determine whether the signature detection event is a false positive or a legitimate malware detection. The security server provides the result of the evaluation to the client from which the report was received.