They can write crap all they want to. It can't do anything without root
access, which it won't have. It can't even write to a file anywhere
without permissions.
If that were all that was required for a system to be secure then
Vista would be 100% secure since all users are only "Standard Users"
(non-Admins) under all default situations.
Have you ever used Linux? The is the boot directory.
See what happens when even the user tries to remove a file. ls=dir, rm=del.
Most users that are going to the command line in Linux aren't getting
much malware in ANY OS. It's the people who don't know/don't care
about getting to know the guts of their computer that get malware.
They've got better things to do with their lives then to muck around
with this stuff, they just want their system to work. When they
install a new app and they get a pop-up requesting admin access they
are either going to stop, think and decide if the application is safe,
or they blindly write in their admin password. This can happen in
Windows Vista, Linux or OS X, all three now use a very similar setup
in this regard.
Sadly, while this is an important first step, more then this is
required to make a system secure. Security of any OS is not something
that can be taken lightly, it needs to be well thought out from the
ground up. Before WinXP SP2 Microsoft did a VERY poor job of thinking
this through, opting for the "easy and dumb" solution instead. The
reason why MS had so many security problems, beyond the obvious issue
of popularity, is because their whole design concept was bad. It
didn't matter how many patches they released to plug holes, it was
never going to fix the underlying concept. They finally changed this
around for SP2 and have taken it further with Vista.
