Attachments in the WorkBench are not yet available in Specify 7, but it will be introduced in the next update of Specify 7 (7.11.2) which is currently in development. This will be available in the coming weeks!
For now, Specify 7 has the Batch Attachment Uploader utility which allows you to upload bulk attachments/images and link them to existing records in the system as long as the filename matches an identifier (catalog number, loan number, preparation barcode, etc.)