TYPO3 Core

There are actually other parameters that could be overridden by an extension and which might cause some misery to a site, so it's nearly impossible to check for every situation without actually scanning every extension's ext_localconf.php file which would be a huge overhead (although it could probably also be done by a scheduler task).

To me it seems more like a problem of educating administrators. It could be something that goes in the (upcoming ;-) security guide.

Well, I agree: Administrators should know what they install.

However, here is my solution:

Let's do it with the install tool password similar to the DB connection data:

Set it in localconf.php as a variable, and then make a constant out of it, before including all the extensions stuff.

Attached is a first try of my approach.

Seems to me more like a feature than a security issue.