I obtained an app that was not what it was labelled as. After opening it, safari windows kept on closing straight after I opened it. I removed the app and everything is fine, so it seems. To be on the safe side, I ran ClamXAV which found no threats. I don't know whether to trust this or reinstall OS fresh. I have all my passwords to everything on my keychain on my Mac. I have read however that the macOS has XProtect which is apparently a background process so since nothing has popped up I assume it is OK. When installing the app, it was initially blocked since it was third party, however I went into the security preferences to allow the app to open (like I had done with previous (maybe more trustworthy) third party apps); does this bypass the whole gatekeeper security system? And when the app was opening after I allowed it, it took some time while it was being 'verified'- I assume this is the Mac searching for viruses etc?