Your use of the term backdoor was probably the trouble, as a backdoor is generally an *unauthorized* way of gaining access to a system- like a secret password left in by a developer so they can muck about if they get fired or whatever. The concern was, I think, that you were accessing remote systems without authorization. Presumably that is not what you mean.
You should be fine to use the net use command \\Host\C$ /user:<username> <password> ...Not sure what you intend to automate. I suppose, you could have a script prompt for the username/pass/hostname first?
echo Enter Host Name to connect
set /p useHost=
echo Enter username
set /p useUser=
echo Enter password
set /p usePassword=
net use \\%useHost%\C$ /user:%useUser% %usePassword%
explorer \\%useHost%\C$
If the username is the same across them (Administrator for example) You could remove the prompt and have it only ask for the password. net use probably returns an errorlevel if it fails as well in which case it would be reasonable to not run explorer trying to load up the share folder too, but this is the basic idea.
