I have started working as sysadmin at a company that uses Microsoft 365. Before I started a few generically named accounts with the Global Administrator role were being used by multiple people to do most day to day admin. No documentation.
I'm trying to tidy this up so we no longer have as many GA accounts and can have accounts with specific needs allocated more granular roles. The team are no longer using these generic accounts to do things, but some service accounts with Global Admin role must have been set up to do scheduled tasks as they are still showing up in the SigninLogs.
I've followed Microsoft guidance to audit when they sign in in Azure Log Analytics, using this query:
SigninLogs | project UserPrincipalName | where UserPrincipalName == "admin@domain.com"
which tells me how frequently a particular account is used, but I'm not sure how to figure out what it is doing. What queries will help me track all the activities down?