Is not setting a System/User proxy for internet connections a security benefit?

Question

Assuming you have a company network and all internet traffic is going through an http-proxy. The users have either a system proxy or a proxy set in their browser settings (i.e. through group policies). Assume now, for administrative work you have admin machines and admin accounts - on the same network - but as you don't want them to have internet access, you just don't set the proxy settings. Is there any real security benefit when you do NOT set a proxy for your admin accounts and on your admin servers? I feel like this is more of a security-by-obscurity case, but can not quite put my finger on it.

Answer 1

Not having a proxy configured when a proxy is needed for internet access prevents most internet access, which includes accidental access, telemetry and probably most malware. Only software which is a) explicitly not relying on common proxy settings and b) knows which internal proxy must be used can access the internet.

Since the internal proxy might be easily guessable (i.e. try common names, common ports) it is even better to require authentication at the proxy and maybe also block specific users/systems from accessing the proxy or limiting which sites can be reached by these users/systems.

I feel like this is more of a security-by-obscurity case, ...

Security-by-obscurity is not generally bad, it is only a problem if one fully relies on it as the only security layer and believes that this is sufficient. If used as an additional layer it can actually add value. It has also some value if no other security layer is used, but then one has to be aware of the severe limitations and acknowledge the remaining risks.