The following article contains tips about uploading and managing files in CKEditor. Refer to the File Manager section of the documentation for more information about this topic.
How Do I Upload Files or Images Using CKEditor?
How Do I Paste a Local Image from my Clipboard to CKEditor?
Since CKEditor 4.5 it is possible to enable uploading images pasted from clipboard or dragged and dropped into the editor. Please refer to the Uploading Dropped or Pasted Files article for more information.
Do note that this still requires integrating a file manager to handle the server-side part of the upload.