- Win9x: Everyone is “admin”
- NT4: OpenThreadToken/OpenProcessToken + GetTokenInformation(…,TokenGroups,…) on DOMAIN_ALIAS_RID_ADMINS SID in a loop
- 2000+: OpenThreadToken/OpenProcessToken + CheckTokenMembership on DOMAIN_ALIAS_RID_ADMINS SID
Other alternatives are: IsUserAnAdmin or AccessCheck
Checking the TOKEN_ELEVATION* stuff in the token is not required for testing the current process but it is useful if you need to find out if the user could elevate because they have a split token etc.