From my time as a SysAdmin I always defined Authentication as the process of verifying an users identity, essentially logging on. Athorisation was the process whereby certain file shares, printers, or applications were made accesible to them through GPOs. Fairly simple differentiation then, authentication lets the system know who is logging in, and then some protocols define what that person is allowed to do / access, similar to access cards where a printed ID shows a person has certain clearance and some RFID locks will grant access to certain areas.
The exam centre authenticated who I was by verifying my ID card. For the 3 computer based exams I was provided an user number and a system generated password. At the first component I thought they were only authenticating me, and the exams were being distributed centrally. At the 2nd exam I saw that with our login they were also ensuring we were only doing the required exam component. The user number remained the same, but the passwords changed.
3 exams, 1 username, 3 passwords. My guess is that on login, the username is validated and then a login hash created with both the username and password is tested against the central service. If the given password is incorrect, no login is possible wether that’s due to a wrong password or the exam not being available yet. So now I’ve authenticated myself with the exam centre (ID), on the central service (user number, pw) and then by logging in I’ve been authorised to take part in the exam.
This is no longer AD authentication and SSO. The login function essentially managed both authentication and authorisation. But, could these authentication processes all also be authorisation? The ID check proves my identity, and because I’m on the register am allowed to take part in the exam. Arguably the invigilators authorised me before authenticating, given they checked ID against roster before verifying the ID was real. You can establish similar controls on infrastructure limiting which services an user can connect to, when they can connect to the services and more importantly, what they can do with the services.
The clear takeaway from this is that I need to play with AD more. The more subtle takeaway is that when securing an infrastructure, it is not enough to limit access to data & applications to registered & allowed users, but it is also important to limit what those users can access. For example, the HR intern should not be looking into the finance folders at 3am on saturday. As we move to cloud based solutions and companies which can start employing remote workers, being able to limit when users can connect to the infrastructure provides a little help in mitigating both insider threat (reduced timeframe) and compromised accounts.