Computer-implemented methods and systems for creating or updating approved-file and trusted-domain databases and verifying the legitimacy of files are disclosed. A method for creating or updating an approved-file database may include intercepting a first file, identifying a source domain associated with the first file, identifying a trusted-domain database, determining whether a database record for the source domain associated with the first file exists within the trusted-domain database, creating a hash value for the first file if a database record for the source domain associated with the first file exists within the trusted-domain database, and storing the hash value for the first file in an approved-file database. Methods and systems for verifying the legitimacy of a file and for creating or updating a trusted-domain database are also disclosed.