Keychain Access security concerns
On High Sierra 10.13.6
I'm not quite sure how to even phrase this. Basically, I'm concerned about security of my Keychain Access app. I was originally under the impression that keychain only stored stuff if you told it to, if you set it up and either added things directly or gave confirmation when prompted. Is this not the case?
Unfortunately, I can't remember exactly what prompted me to even look (I think I was looking at Activity Monitor and it led me to this), but I recently opened Keychain Access and noticed that there are quite a lot of items in there (under the login and local items keychains) that I never 'approved'. Some of what is in there, I suppose I can understand it being added automatically, if it's necessary to sync with the cloud, but others I am not so sure.
I have never wanted to use Keychain, I never opened it prior to this, I did not and do not have it enabled under system preferences for iCloud on either desktop or mobile, anytime something asks me if I wanted to save a password I decline (with the exception of maybe wifi network credentials).
But there's a whole lot of stuff in there and what's more troubling is that I had the hard drive replaced around 05/09-05/13. I got it back on 05/14. I did not restore from a backup, I basically started over from a clean install. However, there are items that show modification dates from 05/09 and 03/30.
Also, I have never used or 'set up' Back to My Mac or Find My Friends and I have not used Facetime or Find My iPhone on this machine since getting it back from having the hard drive replaced. I don't have any of those set up or enabled on my desktop or mobile. But these all have application passwords stored in Keychain and they update frequently. That is, the modification dates on these update very frequently despite me never opening or accessing these apps. It seems to happen any time I open system preferences, not sure if it does otherwise.
To start, I'd like to know what items can be safely deleted from Keychain Access without setting off a cascade of other problems. What items are 'default' and necessary for basic functionality? I've seen some posts about people deleting things or resetting and then having major headaches.
iMac 21.5", macOS 10.13
