https://wordpress.org/plugins/uploadplus/

Filenames on the web are different than those on the desktop. Empty spaces and strange characters doesn’t belong to web space. Enter UploadPlus: you can set your rules and clean your files’ name while they upload. Three basic rules:

• keep only alphanumeric [A-Za-z] and digits, spaces and strange characters stripped out;
• convert spaces and strange characters into dashes (-)
• convert spaces and strange characters in underscores (_)

You can apply website-based or date-based prefix, even a custom prefix. Lowercase or Uppercase? Your choice! Some default prefix:

• time/date based timestamps via PHP date()
• blog name/slug
• random
• and many more!

UploadPlus can also transliterate filenames (text conversion from a non-latin script to raw latin characters). You can preview settings in the media settings page without uploading files.

NEW: EXIF header malware/backdoor sanitization!