SYSTEMS AND METHODS FOR CLASSIFYING FILES WHOSE PREVALANCE WITHIN A USER COMMUNITY IS BELOW A PREDETERMINED THRESHOLD BASED AT LEAST IN PART ON ACTIONS TAKEN BY USERS AFTER BEING INFORMED THAT THE TRUSTWORTHINESS OF THE FILES IS UNKNOWN

A computer-implemented, server-side method for classifying unknown files based on user actions may include (1) identifying at least one file whose trustworthiness is unknown, (2) identifying a report received from at least one client device that identifies at least one action taken by a user within a user community when informed by security software on the client device that the trustworthiness of the file is unknown, (3) determining that the action taken by the user indicates that the user believes the file is trustworthy, (4) classifying the file as trustworthy based at least in part on the action taken by the user, and then (5) providing the file's classification to at least one computing device in order to enable the computing device to evaluate the trustworthiness of the file. Corresponding systems, encoded computer-readable media, and client-side methods are also disclosed.