Systems and methods for protecting backed-up data from ransomware attacks

The disclosed computer-implemented method for protecting backed-up data from ransomware attacks may include (1) determining that a backup system periodically backs up at least one file stored at a computing device to a remote storage system by storing a copy of the file at the remote storage system, (2) identifying one or more characteristics of the file backed up by the backup system, (3) storing a tripwire file with the one or more characteristics at the computing device, (4) determining that the file stored at the computing device has likely been encrypted by ransomware executing on the computing device by detecting that the tripwire file has been modified, (5) performing an action that prevents the backup system from replacing the copy of the file at the remote storage system with a copy of the encrypted file. Various other methods, systems, and computer-readable media are also disclosed.