An apparatus comprises at least one processing device comprising a processor coupled to a memory. The processing device is configured to identify artifacts in a plurality of messages of an account of a user, and to replace the identified artifacts in the messages with respective modified artifacts while also maintaining in access-controlled storage at least information related to the identified artifacts. The processing device receives from a requestor a request for a given one of the identified artifacts that has been replaced with a corresponding modified artifact, determines a profile of the requestor based at least in part on the request, makes a security determination based at least in part on the determined profile, and takes at least one automated action based at least in part on the security determination.