Files on laptop are accessible overnetwork without logging on.

[Ron]

I have discovered by accident that I am able to access the shared files on my
laptop PC from my desktop PC over a local wireless network even when I have
not logged on to the laptop. This behavior is seen when running two different
applications on my desktop for backing up files to the laptop and comparing
files and folders between the laptop and desktop machines. I'm wondering if
this represents a security hole in Windows XP Professional SP-3 or a secure
feature of networking. I run Windows XP Pro SP-3 on both machines.

 

[John Wunderlich]

I have discovered by accident that I am able to access the shared
files on my laptop PC from my desktop PC over a local wireless
network even when I have not logged on to the laptop. This
behavior is seen when running two different applications on my
desktop for backing up files to the laptop and comparing files and
folders between the laptop and desktop machines. I'm wondering if
this represents a security hole in Windows XP Professional SP-3 or
a secure feature of networking. I run Windows XP Pro SP-3 on both
machines.

Since you have XP Pro on both machines, the important detail left out
is whether you are using "Simple File Sharing" or not. When connecting
to any other computer, you must authenticate to it.

With Simple File Sharing enabled (default), all connections are forced
through the "Guest" account and individual permissions are non-
existant. XP _Home_ forces Simple File Sharing to be enabled.

With Simple File Sharing disabled, then you must authenticate based on
username and password. By default, the username and password of the
user on the connecting machine is attempted on the target machine. If
you have the same username and password on both machines, then you will
automatically be authenticated without challenge. If the same
usernames exist on both machines but the passwords are different,
connection is denied. Otherwise, it will ask for username and password
to connect.

See also:
"How to disable simple file sharing and how to set permissions on a
shared folder in Windows XP"
<http://support.microsoft.com/kb/307874>

HTH,
John