first Log in to an administrator account
2. Open System Preferences and go to the App Store
3. Lock the padlock if it is already unlocked
4. Click on the padlock to unlock it
5. Please enter your account username and any password
Note, however, that we will not be able to pass the password on a Macbook Pro with Mac OS 10.13.0, while Macrumors successfully recreates the problem just as described under 10.13.2. It is therefore possible that the problem is isolated to 10.13.2, possibly even 10.13.1.
Apple has not commented yet, but the bug should already have a solution in Mac OS 10.13.3 that is currently in beta states.
Although this is an embarrassing mistake, this bug is, in practice, not as serious as the previous root bug. Secondly, the settings reached are not as critical, and we must be logged in to an administrator account for the bug to "work". If we are logged in to a regular user account, you can not pass the password. Neither under 10.13.0, nor under Mac OS 10.12.6 and earlier.