Help. This may just be my usual paranoia speaking but how do you target unknown enemies who might be slandering you or taking actions against you?
How about if you only know their face and general description, but not their complete name and birthdate?
You don’t need those things if you are actually attacked by them. The attacks create an energetic link that can be traced back or severed or used in a good ol’ return to sender (however you wish to manage your options). Work with what you have, it suffices 
How do I find that link if I have incomplete information about that person?
For starters, you could use classic divination methods. I tend to use different ones to find a common denominator in each of them. What comes through the strongest in different readings serves as my point of focus.
Edit: if you plan to consult a third party here, I would formulate the question as “What is currently going against my _ insert attacked aspects of your life _” instead of “Who is attacking me”. The reader is less biased that way and will be able to clarify the energetic nature of these attacks instead of pushing the description of a person into the reading for the sake of it.
If you are a bit firm with feeling energy signatures you could put that skill to use, as well
If you’re into spirit workings I would suggest Andromalius. Ask him to expose the attacker, they usually tend to give themselves away.
If you simply wish to move on from this without focusing too much on “Who dunnit” I would suggest a Return to sender ritual. There are many approaches to this on this board, @crookedpathfinder shared a simple yet effective way here:
If you don’t have any clues and no tools at your disposal to securely identify the source of these attacks I would use the latter method first. Its easy to get caught up in wild guessing and attacking the wrong individuals; keeping a cool head is the dictate of the moment ESPECIALLY if you don’t have tangible proof about the attacker on your hands
But you don’t have incomplete information. They are “that person who is attacking me.” You know who they are, it doesn’t matter what society calls them.
Just state something like “my known and unknown enemies.”
Thank you loves!